sequence stratigraphy of an alluvial fan-delta in the upper marine molasse (pfänder area, late...

Addresses of the authorsDipl-Geol Dorothea Frieling (dfrielinglrzuni-muenchende) Prof Dr Bettina Reichenbacher Department fuumlr Geo- und Umweltwissenschaften Palaumlontologie amp Geobiologie Ludwig-Maximilians-Universitaumlt Muumlnchen Richard-Wagner-Str 10 D-80333 MuumlnchenDr Michaela Aehnelt Department of Earth and Ocean Sciences University of Liverpool 4 Brownlow Street Liverpool L69 3GP UKProf Dr Herbert Scholz Lehrstuhl fuumlr Ingenieur-Geologie der Technischen Universitaumlt Muumlnchen Arcisstr 21 D-80290 Muumlnchen

Z dt Ges Geowiss 1604 p 333ndash357 12 figs 1 tab Stuttgart December 2009 Article

DOI 1011271860-180420090160-03331860-18040160-0333 $ 1170

copy 2009 E Schweizerbartrsquosche Verlagsbuchhandlung D-70176 Stuttgart

Sequence stratigraphy of an alluvial fan-delta in the Upper Marine Molasse (Pfaumlnder area Late Burdigalian Miocene)

Dorothea Frieling Michaela Aehnelt Herbert Scholz amp Bettina Reichenbacher

Frieling D Aehnelt M Scholz H amp Reichenbacher B (2009) Sequence stratigraphy of an alluvial fan-delta in the Upper Marine Molasse (Pfaumlnder area Late Burdigalian Miocene) [Sequenzstratigrafi e eines alluvialen Fan-Deltas in der Oberen Meeresmolasse (Pfaumlnder-Gebiet juumlngeres Burdigal Miozaumln)] ndash Z dt Ges Geowiss 160 333ndash357 Stuttgart

Abstract The Pfaumlnder ridge east of Lake Constance (Southwest Germany) is composed of clastic sediments of the Lower Freshwater Molasse the Upper Marine Molasse and the Upper Freshwater Molasse Here we present a sedimentological and sequence stratigraphical study on the deltaic deposits of the Upper Marine Molasse that formed during the EggenburgianOttnangian transgression (Lower Miocene) in front of the alluvial Pfaumlnder Fan Specifi cally we focus on the deltaic succes-sion to the Northeast of the talus centre Within this we investigated four sections up to 400 m thick in the area between Bregenz (Vorarlberg) and Weiler (Allgaumlu) Four sedimentological units were defi ned (1) the ldquobasalrdquo conglomerate (2) the monotonous ldquozone of glauconitic sandstonesrdquo (3) the heterogenous ldquozone of the delta faciesrdquo with sandstones thin marl layers and conglomerates (4) the ldquozone of marls and fi ne-grained sandstonesrdquo The sections display from northeast to south-west a successive change from a distal shallow marine environment with no or very little infl uence from the Pfaumlnder Fan (Rothenbach and Kesselbach sections) to a proximal shallow marine environment with strong deltaic infl uences (Huberbach and Leckenbach sections) We suggest fi ve base level cycles forming two transgressive-regressive sequences for the Upper Marine Molasse The lower sequence (base level cycles I to III) is correlated with the Eggenburgian its highstand systems tract is represented by deltaic sediments (base level cycles II and III) The upper sequence for which we assume an Ottnang-ian age can be subdivided into two base level cycles (IV and V) They probably can be correlated with the two known transgressive-regressive cycles of the Ottnangian in the southwestern German part of the Molasse Basin

Kurzfassung Den Pfaumlnder-Ruumlcken oumlstlich des Bodensees (Suumldwestdeutschland) bauen klastische Sedimente der Unteren Suumlszligwassermolasse Oberen Meeresmolasse und Oberen Suumlszligwassermolasse auf Die waumlhrend der untermiozaumlnen marinen Uumlberfl utung (EggenburgOttnang) im Vorfeld des alluvialen Pfaumlnder-Faumlchers abgelagerten deltaischen Sedimente wurden sedimentologisch und sequenzstratigrafi sch untersucht Die vier untersuchten Profi le liegen zwischen Bregenz (Vorarlberg) und Weiler (Allgaumlu) und umfassen eine fast 400 m maumlchtige Abfolge im randlichen Deltakoumlrper nordoumlstlich des Schuumlttungs-zentrums Es wurden vier sedimentologische Einheiten defi niert (1) das bdquoBasalldquo-Konglomerat (2) die monotone bdquoZone der glaukonitischen Sandsteineldquo (3) die heterogene bdquoZone der Delta-Faziesldquo mit Sandsteinen Mergellagen und Konglomeraten und (4) die bdquoZone der Mergel und feinkoumlrnigen Sandsteineldquo Von Nordosten nach Suumldwesten zeigen die Profi le einen all-maumlhlichen Uumlbergang von einem distalen fl achmarinen Ablagerungsraum ohne oder mit nur sehr geringer Beeinfl ussung durch den Pfaumlnder-Faumlcher (Rothenbach und Kesselbach) zu einem proximalen fl achmarinen Sedimentationsraum mit star-kem deltaischen Einfl uss (Huberbach und Leckenbach) In der Abfolge sind fuumlnf bdquobase levelldquo-Zyklen nachweisbar welche zwei transgressiv-regressive Sequenzen aufbauen Die untere Sequenz (bdquobase levelldquo-Zyklen I bis III) umfasst den Zeitraum des Eggenburg ihr bdquohighstand systems tractldquo wird durch deltaische Sedimente gebildet (bdquobase levelldquo-Zyklen II und III) Die obere Sequenz fuumlr welche ein Ottnang-Alter angenommen werden muss ist in zwei bdquobase levelldquo-Zyklen (IV und V) unter-gliederbar welche houmlchstwahrscheinlich mit den bekannten zwei transgressiv-regressiven bdquoZyklenldquo im suumldwestdeutschen Anteil des Molassebeckens parallelisierbar sind

Keywords Pfaumlnder Southwest Germany Vorarlberg Upper Marine Molasse (OMM) Miocene deltaic complex sequence stratigraphy lignite coal

Schluumlsselwoumlrter Pfaumlnder Suumldwestdeutschland Vorarlberg Obere Meeresmolasse (OMM) Miozaumln Delta Sequenzstratigrafi e Braunkohle Kohle

eschweizerbartxxx ingenta

334 Dorothea Frieling et al

1 Introduction

Since more than 100 years the Pfaumlnder area has received considerable attention initially because of the presence of economically important lignite coal seams and fossiliferous horizons The Pfaumlnder sediments belong to a mainly marine succession ndash the Upper Marine Molasse ndash and developed in front of a large alluvial fan as part of a deltaic complex of which the most proximal part (talus centre) is the well-known Wirtatobel section (Schaad et al 1992)

The geographic location of the Pfaumlnder (Fig 1) should be ideal for a correlation of the Upper Marine Molasse between Switzerland and Southwest Germany which still bears con-siderable uncertainties (cf Reichenbacher et al 2005) How-ever due to the mostly deltaic environment of the Pfaumlnder sediments such a correlation had not been attempted up to date In this study we focus on the so far not investigated distal part of the Pfaumlnder delta to the Northeast of the talus centre We investigated the lithofacies lithostratigraphy and sedimentary environment at four well exposed sections and performed a sequence stratigraphical analysis We also at-tempted bio- and magnetostratigraphical techniques which however failed because of the special sedimentary condi-tions as the sedimentation rate was high and fi ne-grained clastic layers were scarce or even lacking Our data show that lithostratigraphic correlation is possible between the proximal and distal portions of the Pfaumlnder delta Further-more we suggest a new correlation scheme for the Upper Marine Molasse in southwestern Germany and eastern Swit-zerland

2 Study area

21 Geography

The Pfaumlnder ridge (height 1064 m) rises above Bregenz at the eastern margin of Lake Constance in the southwestern corner of the South German part of the Molasse Basin (Fig 1C) Its northern slopes gradually pass into the North Alpine Foreland whereas the steeper southern slopes expose the Early Miocene sediments of the Upper Marine Molasse in deeply incised gorges (ldquoTobelrdquo in the local dialect) The deepest of these gorges are the Wirtatobel directly beneath the summit of the Pfaumlnder Mountain and the Kesselbach southeast of the summit marking the AustrianGerman state border (Fig 1D) Only the Upper Marine Molasse succes-sion of the Wirtatobel has been studied before (eg Blumrich 1930 Ploumlchinger et al 1958 Herrmann amp Schwerd 1983 Schaad et al 1992)

22 Geology

221 Overview

The Molasse Basin is bordered by the Alpine nappes to the South the Variscan crystalline basement rocks of the Bohe-

mian Massive to the Northeast and the Mesozoic strata of the Alb and Swiss Jura mountains to the North and North-west (Fig 1C) During the Oligocene and the Miocene clas-tic sediments accumulated in the basin under terrestrial and marine conditions They mostly contain debris derived from the quickly growing Alps to the South (eg Lemcke 1988 Scholz 2000)

Repeatedly the basin was invaded by the sea (eg Allen et al 1985 Tessier amp Gigot 1989 Kuhlemann amp Kempf 2002) and became part of the western Paratethys In the Early Miocene (Eggenburgian) a seaway intermittently extended from the Caspian Sea via the Molasse Basin to the Rhocircne Valley and the Tethys the today Mediterranean Sea (Roumlgl amp Steininger 1983 Bieg et al 2008) During this time alluvial fans and delta complexes supplied by Alpine debris from the South prograded northward towards shallow marine envi-ronments fi lling the Molasse Basin In the late Early Miocene (Ottnangian) the fi nal period of marine sedimentation was succeeded by the deposition of the Upper Brackishwater Molasse and the Upper Freshwater Molasse (Lemcke 1988 Reichenbacher 1993)

The present study focuses on the sediments of the Upper Marine Molasse which were deposited during the Early Miocene in the Eggenburgian and Ottnangian (approxi-mately 20ndash17 Ma ago Wenger 1987a Berger et al 2005) The stratigraphy of these sediments is based on benthic fo-raminifera from the Southeast German and Austrian part of the basin (Hagn 1959 1961 Knipscher 1952 Wenger 1987a b Pippegraverr et al 2007a b Pippegraverr amp Reichenbacher 2009) However in the proximal coastal areas foraminifera are scarce andor poorly preserved (see Wenger 1987b and this study) due to high sedimentation rates and coarse grain sizes In the central and West German part of the Molasse Basin at least two transgressive-regressive cycles were recognised in the Upper Marine Molasse on the basis of differences in the lithofacies (Lemcke et al 1953 Schreiner 1966 Gall 1975

Fig 1 Simplifi ed maps of (A) Germany (frame indicating position of C) and (B) of the Molasse Basin (frame indicating position of C) (C) German part of the Molasse Basin (white colour) with study area (frame) areas with outcropping Upper Marine Molasse are shown in grey colour Cliffl ine sensu Lemcke (1988) Map source Geological map of the South German Molasse 1 300 000 Abele et al (1955) (D) Geological map of the Pfaumlnder area (simplifi ed) with the studied sections modifi ed after Scholz (1993) W = Wirtatobel section L = Leckenbach section H = Huberbach section K = Kes-selbach section R = Rothenbach section

Abb 1 Stark vereinfachte Kartendarstellung von (A) Deutschland (der Rahmen zeigt die Lage von C) und (B) des Molassebeckens (der Rahmen zeigt die Lage von C) (C) Der deutsche Anteil des Molassebeckens (weiszlig) mit dem Untersuchungsgebiet (Rahmen) die Gebiete mit uumlber Tage ausstreichender Oberer Meeresmolasse sind grau dargestellt Die Kliffl inie ist im Sinne von Lemcke (1988) dargestellt Kartengrundlage Geologische Uumlbersichtskarte der Suumlddeutschen Molasse 1 300 000 Abele et al (1955) (D) Geolo-gische Karte des Pfaumlnder-Gebietes (vereinfacht) mit den bearbeite-ten Profi len veraumlndert nach Scholz (1993) W = Wirtatobel L = Leckenbach H = Huberbach K = Kesselbach R = Rothenbach


335Sequence stratigraphy of an alluvial fan-delta in the Upper Marine Molasse (Pfaumlnder area Late Burdigalian Miocene)



Pippegraverr et al 2007b) In contrast Heimann et al (2009) as-sume the existence of only one cycle

The coastal area at the southwestern margin of the Ger-man part of the Molasse Basin is the regional context of the present study (Fig 2A) It was characterised by large deltaic complexes produced by alluvial fans from the Alps with bays in-between (Fig 2B see also Lemcke 1988 Geyer amp Gwinner 1991) The coastline may have shifted in the range of kilometres and was controlled by the sedimentary input the subsidence of the basin the compaction of the sediments and the rise and fall of the relative sea level (eg Lemcke 1988 Zweigel 1998) East of Lake Constance a forerunner of river Bregenzer Ach formed the Pfaumlnder Fan which prob-ably was an active alluvial fan since the Eggenburgian and the beginning of the Upper Marine Molasse respectively (Schiemenz 1960) To the West the Pfaumlnder Fan was bor-dered by the Houmlrnli Fan (fed by the Palaeo-Rhine) and to the East it was bordered by the Hochgrat-Adelegg Fan (fed by the Palaeo-Iller see Fig 2) The Pfaumlnder Fan was relatively small in comparison with the Houmlrnli and Hochgrat-Adelegg Fan both real mega-fan systems

222 The Pfaumlnder area

The Pfaumlnder ridge is part of the foreland dip panel defi ning the southern margin of the autochthonous Molasse The

mountain ridge extends SSWndashNNE and is thus more or less parallel to the strike of the Molasse beds It is composed of up to 400 m thick marine sediments of the Upper Marine Molasse and the overlying terrestrial deposits of the Upper Freshwater Molasse (see Fig 1D) The Molasse beds dip with 15ndash20deg to the Northwest (310ndash320deg azimuth) and ge-netically belong to the Pfaumlnder Fan As a whole the Upper Marine and Upper Freshwater Molasse form a coarsening-upward succession as thickness grain size and frequency of conglomerate layers increase with age from the older to the younger beds At places where they are not covered with a thick blanket of Quaternary sediments the locally very coarse-grained conglomerate layers form large steps at the steep western slopes of the Pfaumlnder

The conglomerates in the Pfaumlnder Fan are mainly com-posed of sandy limestones and spiculitic cherts and lime-stones containing more than 90 fl ysch pebbles Few peb-bles consist of glauconitic quartz sandstones and limestones with Corallinaceans and Nummulites that perhaps may de-rive from the Helvetian nappes An Actaeonella fi nd may derive from Gosau deposits (recent completely eroded Hagn 1992) Thus the catchment area of the Palaeo-Bregenzer Ach predominantly was the Rhenodanubian Flysch unit (Fig 2B)

The Upper Marine Molasse in the Pfaumlnder region has been known since the 19th century Underground coal mines

Fig 2 (A) Simplifi ed palaeogeographic map of the Molasse Basin during the deposition of the Early Miocene Upper Marine Molasse (after Scholz 1995) (B) Schematic palaeogeographic sketch of southwestern Bavaria during the deposition of the Upper Marine Molasse H = Helvetian which has been mostly covered by Flysch nappes

Abb 2 (A) Vereinfachte palaumlogeografi sche Karte des Molassebeckens waumlhrend der Ablagerung der untermiozaumlnen Oberen Meeresmolasse (nach Scholz 1995) (B) Schematische palaumlogeografi sche Darstellung Suumldwestbayerns waumlhrend der Ablagerung der Oberen Meeresmolasse H = Helvetikum welches hauptsaumlchlich von Flysch uumlberdeckt ist



had been active near Bregenz from 1840 until after the World War II (Schmidt 1843 1879 Guumlmbel 1896 Blumrich 1908 1930 1948 Schmidt amp Muumlller 1911 Schmidegg 1945 Jaumlger 1957 Heinrich 1980 Weber amp Weiss 1983 Weiss 1984 Kuntscher 1986 Hofmann 1997 and also various expert opinions about the coal mining 1909ndash1911) Various studies concerned the Wirtatobel section and the western area adja-cent to it The Upper Marine Molasse of this region was sub-divided into the Luzern Formation below and the St Gallen Formation above (eg Blumrich 1930 Herrmann amp Schwerd 1983) a correlation with eastern Switzerland seems to be well founded (eg Keller 1989 1990 Schlunegger et al 1997a b Schaad et al 1992) The Luzern Formation in the Wirtatobel section is separated from the St Gallen Forma-tion by the Pfaumlnder coal seam between both formations However the coal seam which is in the Wirtatobel up to 70 cm thick thins out to the NE Thus the separation of the Luzern Formation and the St Gallen Formation becomes ob-scure and fi nally impossible (Herrmann et al 1985 this study) As a result the lithostratigraphic names Luzern For-mation and St Gallen Formation are generally no longer in use in the region to the Northeast and East of the Wirtatobel Furthermore a subdivision in chronostratigraphical units ie a Burdigalian and a Helvetian succession was proposed by Heim et al (1928) and Rutsch (1928) for the Pfaumlnder area but not adopted by younger authors as the term Helvetian bears signifi cant uncertainties with regard to its stratigraphi-cal range (see Fahlbusch 1981 Scholz 1999)

3 Material and methods

Four sections in gorges at the southeastern slope of the Pfaumlnder which each exposes the 340 to 380 m thick Upper Marine Molasse succession were mapped in detail and measured sections taken (Fig 3) Leckenbach and Huber-bach section in Vorarlberg (GK 25 no 82) Kesselbach and Rothenbach section in Bavaria (TK 25 no 8425) The Wirta-tobel section (see Schaad et al 1992) was included for com-parison (see Fig 9)

Nineteen marly and fi ne-grained sandy layers were sam-pled for micropalaeontological investigations and thin sec-tions from 30 sandstones from different stratigraphic levels were examined

4 Results

41 Facies types

The Upper Marine Molasse succession of the Pfaumlnder area contains several facies types (the abbreviations given in brackets are used throughout the following chapters)

ndash Monotonous glauconitic sandstone facies (GS) re-stricted to the lower third of the succession fi ne- to medium-grained sandstone glauconite-rich very poor in micro- and macrofossils parallel-laminated and low-angle cross-lami-nated partly thin-platy abundant ripple surfaces (oscillation

ripples and interference ripples) often bioturbated isolated thin pebble layers (see type T) this facies type is essentially in accordance with lithofacies B of Schaad et al (1992)

Interpretation wave-dominated facies association with sediments of a coastal area between the transition zone and the foreshore

ndash Fluvial conglomeratic facies (FC) mainly in the mid-dle part of the succession and at the base fi ne- to coarse-grained conglomerates often with erosive base pebble ori-entation mostly uniform mostly a certain portion of the peb-bles are of crystalline rocks sandstone lenses and layers shells and shell fragments of oysters this facies type is es-sentially in accordance with lithofacies L of Schaad et al (1992)

Interpretation supply from fl uvial channels in a deltaic complex

ndash Marine conglomeratic facies (MC) so-called ldquoAusternnagelfl uhrdquo mainly in the middle part of the succes-sion fossil- and matrix-rich fi ne-grained conglomerates or fossil- and pebble-rich coarse-grained sandstones locally with erosive base medium-scale to large-scale cross-bed-ding locally chaotic structure ripple surfaces (oscillation and interference ripples) many shells of oysters (concentra-tion at the top of the horizon) other molluscs barnacles bryozoans locally large fragments of coaly wood typical with a certain portion of crystalline pebbles limestone peb-bles often show holes made by boring molluscs polished quartz pebbles partly intercalations of type SR

Interpretation marine genesis eg as beach ridge depo-sits or deposits of rip channels in the foreshore or upper shoreface

ndash Channel facies (Ch) absent in the lower third of the succession medium- to coarse-grained glauconitic sand-stone medium- to large-scale epsilon cross-stratifi cation festoon bedding ripple surfaces (oscillation ripples) bed-forms with channel morphology intercalations of shell frag-ments and pebbles often associated with facies type t this facies type is essentially in accordance with lithofacies E of Schaad et al (1992)

Interpretation tidal fl at with laterally migrating channels point bar sequences

ndash Channel lag facies (ChL) can occur anywhere in the section accumulations of mollusc shells partly fragments (shell pavement) mostly from one bivalve species or from Turritellidae shells oriented concave side upward pebbles only a small portion of sandy matrix

Fig 3 Schematic logs of the Leckenbach Huberbach Kesselbach and Rothenbach sections (for the topographical position see fi g-ure 1D) The subdivision of the sections into different lithological units is given on fi gure 9

Abb 3 Schematische Darstellung der Profi le Leckenbach Huber-bach Kesselbach und Rothenbach (die Lage der Profi le ist Abbil-dung 1D zu entnehmen) Die Unterteilung der Profi le in verschie-dene lithologische Einheiten ist in Abbildung 9 dargestellt







Interpretation channel lag deposits on the bottom of channels caused by linear erosion (connected with tidal cur-rents)

ndash Storm bed facies (T) can occur anywhere in the sec-tion thin intercalations of pebbles shells mud pebbles lo-cally plant remains or massive fi ne sandstone banks with pebbles and shells

Interpretation reworking by high-energy currents caused by storms or fl oods

ndash Hummocky facies (H) mainly occurs in the facies type GS medium-grained sandstone platy to bedded large-scale cross bedding with fl at angles layers convex as well as concave upward surfaces with oscillation ripples locally bioturbated (Ophiomorpha nodosa)

Interpretation sandstones with storm-induced ripples with large wave-lengths deposited in the lower shoreface in between storm wave base and low-tide level

ndash Ripple facies (r) can occur anywhere in the section fi ne- to medium-grained sandstone wavy layering in vertical section small-scale cross-bedding (ripple bedding) ripple surfaces (often wave-generated)

Interpretation wind- or current-induced ripple structures deposited in the upper shoreface and the foreshore (sand fl ats)

ndash Tidal bedding facies (t) absent in the lower third of the succession sandstone-marl interbedding (heterolithic facies) wavy bedding ripple surfaces on top of sandstone layers sandstone beds with small-scale cross-bedding (rip-ple bedding) occasionally fl ute casts or load casts on the bot-tom of sandstone layers often marly layers very thin partly only marly fl asers (fl aser bedding) locally double mud drapes bioturbation this facies type is essentially in accord-ance with lithofacies F and G of Schaad et al (1992)

Interpretation tide-infl uenced sediments of mixed tidal fl atspoint bar deposits of tidal creeks and shallow subtidal areas (tidal channels with mud drapes deposited in the slack water phase and sandstone beds deposited in the ebb or fl ood phase)

ndash Sand ridge facies (SR) in the middle of the succession and locally intercalated in facies GS large-scale cross-bed-ded glauconitic sandstone with planar laminae dipping con-sistently in the same direction

Interpretation planar barrier cross-bedding of coastal barriers along the low tide level prograding landwards

ndash Laminated facies (L) locally fi ne- to medium-grained sandstone horizontal laminated (lamination is marked by al-ternating layers of different grain size)

Interpretation coastal high-energy deposits developed by swash and backwash actions of waves eg in sand ridges ebb-deltas along the margins of major channels this facies type is essentially in accordance with lithofacies D of Schaad et al (1992)

ndash Nodular sandstone facies (NS) locally intercalated within the succession well sorted fi ne-grained reddish sand-stone thin banks with irregularily shaped nodules solid cal-cite-cemented locally the layering is wavy between the nodular banks there are very thin and fl ame-like red marly skins

Interpretation diagenetic overprinted tidal bedding facies

ndash Reworking facies (R) can occur anywhere in the sec-tion marly resediments (mud pebbles and fragments of peb-bles) locally plant remains

Interpretation sediments reworked by high-energy cur-rents caused by storms or fl oods

ndash Reworking layer with calcrete (RC) horizon in the middle of the Kesselbach section breccia consisting of an-gular white limestone components (reworked calcretes ndash see chapter 425) pebbles large mud pebbles shelly debris and big coal pieces medium-scale cross-bedding intercalations of sandstones layers

Interpretation reworked material of terrestrial origin the coal fragments originally may have been layered peat frag-ments deposited into the shallow marine environment

ndash Rosselia socialis facies (RS) thin trace fossil horizon in the Kesselbach section distinctly lithifi ed fi ne-grained sandstone horizon densely populated by the trace fossil Ros-selia socialis

Interpretation erosional or non-depositional stage on top of a transgressive siliciclastic system (Frieling 2007)

ndash Clastic dyke facies (CD) appears in the lower part of the second third of the Kesselbach section bedded and inter-nal fi ne-laminated fi ne-grained to medium-grained glauco-nitic sandstone strongly bioturbated (large isolated traces of Ophiomorpha linearis passing over to total bioturbation) with two vertical clastic dykes discordantly cutting the bed-ding and connected by a horizontal clastic sill which is rooted in a horizontal root region below

Interpretation deformation structures triggered by seis-mic shocks most likely connected with active tectonic move-ments at the southern rim of or even within the Molasse Ba-sin itself (see Scholz amp Frieling 2006)

ndash Shelf mud facies (SM) restricted to the upper part of the Leckenbach and Huberbach section marl (mudstones mostly clayey partly fi ne-grained sandy) thin-platy bed-ding planes wavy ndash therefore the layering is slightly phacoi-dal small-scale cross-bedding locally thin layers with a higher content of fi ne-grained sand locally intercalations of type T single layers with coaly plant debris partly clearly bioturbated with single distinct traces (Planolites Teichich-nos) isolated small chalky mollusc shells this facies type is essentially in accordance with lithofacies A of Schaad et al (1992)

Interpretation deposits of the transition zone with tem-pestite intercalations

42 Sedimentary succession

From bottom to top the marine Pfaumlnder succession can be subdivided into four units (see Fig 9) (1) the ldquobasalrdquo con-glomerate (2) the monotonous ldquozone of glauconitic sand-stonesrdquo in the lower third (3) the heterogenous ldquozone of the delta faciesrdquo with sandstones thin marl layers and different types of conglomerates and (4) the ldquozone of marls and fi ne-grained sandstonesrdquo in the upper third



A prominent coal layer is intercalated in the ldquozone of the delta faciesrdquo of the southwestern sections

421 The ldquobasalrdquo conglomerate

Previous studiesThe base of the Upper Marine Molasse of the Pfaumlnder suc-cession is exactly defi ned by a basal 2 to 4 m thick conglom-erate (see Guumlmbel 1896 Heim et al 1928 Blumrich 1930 Ploumlchinger et al 1958 Herrmann amp Schwerd 1983 Herr-mann et al 1985 Schaad et al 1992) It is the lowermost conglomeratic layer of the whole coarsening-upward se-quence of the Pfaumlnder Fan and was interpreted as the initial transgressive sediment layer of the Miocene Molasse Sea in this region (Schaad et al 1992) Schaad et al as well as Blumrich (1930) called it ldquobasal conglomeraterdquo without an interpretation of its depositional history The content of crys-talline pebbles attains 12 (Scholz 2000) which is in con-trast with most of the other conglomerates associated with the Pfaumlnder Fan that normally contain only a few percent of crystalline pebbles (Schiemenz 1960 Uhlig 1987 Elsner 2005)

DescriptionThe basal conglomerate is only present in the Leckenbach and the Huberbach section where it is approximately 5 m thick (see also Fig 9) It has a fl uvial habitus (facies type FC) but also contains a distinct proportion of oyster shells The content of crystalline pebbles is higher than in most of the other conglomerates of the marine succession This con-glomerate overlies the grey and yellow marls of the Lower Freshwater Molasse with a sharp erosional base

Sedimentary environment The basal conglomerate seems to be restricted to local de-pressions (as it does not appear in all sections) and its habitus is fl uvial Therefore it can be interpreted as channel fi ll However the oyster shells and the remains of a ray (Lecken-bach Blumrich 1930) point to a marginal marine infl uence Presumably the coastal plain in front of the alluvial fan of the Palaeo-Bregenzer-Ach (north of it) was cut by deeply eroded distal channels of fl uvial streams which were fl ooded at the very fi rst beginning of the rising sea-level At this time the basal conglomerate was formed with a fl uvial origin but deposited in a marine environment A further isolated con-glomerate in this position the so-called ldquoEntschensteinrdquo (or ldquoMenschensteinrdquo) south of Weiler (see Fig 1D) provides additional support It contains oyster shells and shows large scale cross-bedding (unpubl data) and may be a channel fi ll too In places where such fl uvial channels are missing eg at Kesselbach section the initial trangression of the Molasse Sea is marked by a phase of non-deposition

Because of the fl uvial habitus of the conglomerate the comparatively high share of crystalline components may in-dicate a short-termed taping of the Hochgrat-Adelegg Fan system nearby (see Fig 2) rather than a coastal drifting as suggested by Scholz (2000)

422 The ldquozone of glauconitic sandstonesrdquo

Previous studiesThe basal conglomerate is overlain by a monotonous succes-sion of fi ne- to medium-grained glauconitic sandstones the so-called ldquozone of glauconitic sandstonesrdquo (Herrmann amp Schwerd 1983 Schaad et al 1992) that is forming the basal third of the marine succession with a thickness up to 150 m (see Blumrich 1930 Herrmann amp Schwerd 1983 Herrmann et al 1985 Schaad et al 1992) The ldquozone of glauconitic sandstonesrdquo is a part of Kellerrsquos (1989) ldquoLuzern Formationrdquo and can be inter-preted as a wave dominated facies (Schaad et al 1992)

DescriptionThe ldquozone of glauconitic sandstonesrdquo (facies type GS) is present in all studied sections and 50 to 110 m thick (see Fig 9) The content of glauconite in the sandstones varies from lt 1 to 25 Glauconite grains mainly consist of dark-green well-rounded pellet-like granules with diameters up to 2 mm and often show shrinking cracks Glauconite may also appear as fi llings of foraminiferal tests and as pale-green fi lls of interstitial space (Fig 4)

Sedimentary environmentFacies type GS can be interpreted as deposited between the foreshore and the transition zone The shoreface is indicated by sandstones with hummocky cross-stratifi cation parallel laminated thin-platy sandstones with fl at-angled large-scaled cross-bedding and current groove marks Thin coarse-grained shell layers represent the foreshore with systems of beach ridges parallel to the palaeo-coast and rip channels The general monotony of facies type GS implies its forma-tion within a coastal depositional area showing minor diver-sity in morphology or facies High-energetic events like strong currents generated by storms high stands of rivers or tsunamis occur only occasionally (see Fig 3 T H and ChL in the schematic logs)

The origin of glauconiteThe average rate of sedimentation of the marine Pfaumlnder succession is between 013 and 02 mma (calculated from 400 m of sediments within 2 to 3 Ma which have to be as-sumed for the deposition of the Upper Marine Molasse in this region) This comparatively low rate probably results from periods of non-deposition as well as from syngenetic erosion Glauconite generation is generally considered as typical for periods of transgression in environments of mod-erate to slow discontinuous deposition and takes place dur-ing periods of non-deposition (cf Kohler amp Haumlussler 1978 Odin amp Matter 1981 Tucker 1985 Fuumlchtbauer 1988 Einsele 2000) Such an environment model fi ts well with the as-sumed deltaic environment of the Pfaumlnder delta during the transgression of the Upper Marine Molasse As it is obvious from the thin-sections (Fig 4BndashF) most of the glauconite grains in the Pfaumlnder sediments seem to have an organic ori-gin Several authors have explained glauconitisation as or-ganic in origin ie of kaolinite faecal pellets or microfaunal tests by replacement of the primary material in a O2-poor or



O2-free microenvironments like cavities of biogenes or in-testines of sediment feeders (eg Odin 1988 Odin amp Pulla-gar 1988 Odin amp Matter 1981 Einsele 2000) In only few cases a glauconitisation of preexisting biotite granules (cf Fischer 1987) took place

423 The ldquozone of the delta faciesrdquo

Previous studiesTwo conspicuous up to 50 m thick conglomerates are known from the lower part of the ldquozone of the delta faciesrdquo the so-

called ldquoKanzelfels-Nagelfl uhrdquo below and the ldquoGebhards-berg-Nagelfl uhrdquo above (Rutsch 1928 Blumrich 1930 Herr-mann amp Schwerd 1983 Herrmann et al 1985 Schaad et al 1992 Nagelfl uh = conglomerate in the Allemanic dialect) They can be used as marker horizons from the area at Bregenz to the Northeast and have been recognised in the Wirtatobel section (Schaad et al 1992) the Leckenbach section and also in the Huberbach section (see also Herrmann et al 1985) However apart from these distinctive conglomerates a cor-relation of neighboured sections is diffi cult within the ldquozone of the delta faciesrdquo which was explained by the internal

Fig 4 (A) Glauconitic sandstones (facies type GS) in the basal part of the Kesselbach section The main part of these sandstones is thin platy and slightly cross-bedded with very low angles (a few degrees as a maximum) (BndashF) Thin sec-tions of glauconitic sandstones under linear po-larised light from the lower part of the Kessel-bach section showing (B) glauconite pellets (arrows) (C) glauconite grain showing relictic structures of biotite (pseudomorphism) (D) glauconite fi lling interstitial pore space between components (E) glauconite as fi lling of fo-raminiferal tests and (F) glauconite pellet with contraction fi ssures

Abb 4 (A) Glaukonitische Sandsteine (Fa-ziestyp GS) im unteren Teil des Kesselbach-Pro-fi ls Hauptsaumlchlich sind sie duumlnnplattig und un-ter sehr fl achen Winkeln (maximal wenige Grad) schwach schraumlggeschichtet (BndashF) Duumlnnschliffe glaukonitischer Sandsteine aus dem unteren Teil des Kesselbach-Profi ls unter einfach polarisier-tem Licht zeigen (B) Glaukonit-Pellets (Pfeile) (C) Pseudomorphosen von Glaukonit nach Bio-tit (D) glaukonitische Fuumlllungen des Poren-raumes zwischen den Komponenten (E) glau-konitische Fuumlllungen von Foraminiferenschalen und (F) Glaukonit-Pellets mit Schwundrissen



structure with different lobes and bays of the prograding delta (Schaad et al 1992)

DescriptionThe ldquozone of the delta faciesrdquo is characterised by a hetero-genous lithofacies Glauconitic sandstones alternate with thick conglomerates (type MC and FC) and thin horizons of pebbles fi ne-grained marl-dominated sediments are limited to thin intercalations interbedded with sandstones Despite of the short distance between the different sections correlation is hardly possible and single horizons (eg most of the con-glomerates) cannot be parallelised even in closely neigh-boured sections However the prominent FC type conglo-

merates of the ldquoKanzelfels-Nagelfl uhrdquo and the ldquoGebhards-berg-Nagelfl uhrdquo can be recognised in the southwesternmost sections (Leckenbach and Huberbach sections see Fig 3) Compared with the Wirtatobel section their thickness is strongly reduced (up to 15 m for ldquoKanzelfels-Nagelfl uhrdquo 8 m for the ldquoGebhardsberg-Nagelfl uhrdquo) Farther to the North-east thick conglomerates of the FC type are lacking Thicker intercalations of the MC type occur in the Leckenbach and Rothenbach sections (see Fig 3) and include abundant rem-nants of bivalves gastropods barnacles and bryozoan de-bris Such fossiliferous layers can be characterised as detrital limestone containing sand and pebbles It is informally termed as ldquoAusternnagelfl uhrdquo (see Fig 5CndashD) In the

Fig 5 (AndashB) Channel facies (facies type Ch) with epsilon cross-stratifi ed sandstones (A) in the Rothenbach section and (B) in the Kesselbach section (CndashD) Marine conglomerates (bdquoAustern-nagelfl uhldquo MC) in the basal part of the Rothen-bach section (C) Pebbly coarse-grained sand-stone to matrix-rich fi ne-grained conglomerate with many fragments of shells (oyster shell in the centre) and (D) fragments of barnacles (upper third of the picture thin section under linear po-larised light) (EndashG) Tide generated structures in the Kesselbach section (E) Heterolithic tidal bedding facies (t) in the lower part of the ldquozone of the delta faciesrdquo (F) Flute casts on the subface of a fi ne-grained sandstone of the heterolithic facies indicating current directions to the SW (G) Planar barrier cross-bedding (SR) in the ba-sal part of the ldquozone of the delta faciesrdquo

Abb 5 (AndashB) Rinnenstrukturen in Sandsteinen (Faziestyp Ch) mit Gleithangschichtung (A) im Rothenbach- und (B) im Kesselbach-Profi l (CndashD) Marines Konglomerat (bdquoAusternnagelfl uhldquo MC) im unteren Abschnitt des Rothenbach-Pro-fi ls (C) geroumlllfuumlhrender Grobsandstein bis ma-trixreiches Feinkonglomerat mit vielen Schalen-bruchstuumlcken (Austernschale im Bildzentrum) und (D) Bruchstuumlcke von Seepocken (oberes Bilddrittel Duumlnnschliff unter einfach polarisier-tem Licht) (EndashG) Unter Gezeiteneinfl uss ent-standene Sedimentstrukturen im Kesselbach-Profi l (E) Heterolithische Gezeitenschichtung (t) im unteren Teil der bdquoZone der Delta-Faziesldquo (F) Stroumlmungsmarken an der Schichtunterseite von Feinsandsteinen innerhalb der heterolithischen Fazies deuten auf Stroumlmungsrichtungen nach SW (G) Riffstirnschraumlgschichtung (SR) im un-teren Teil der bdquoZone der Delta-Faziesldquo



Leckenbach section this conglomerate contains a signifi cant portion of crystalline components mostly gneisses and other metamorphic rocks

Sedimentary structures are diverse at many places epsi-lon cross-stratifi cation occurs and the coarse-grained layers show erosional surfaces at their base Different facies types of sandstone appear channel lag facies (ChL) channel facies (Ch Fig 5AndashB) with glauconite facies with storm beds (T) hummocky facies (H) facies with ripples (r) heterolithic tidal bedding facies (t Fig 5E) sand ridge facies (SR Fig 5G) even laminated facies (L) nodular facies (NS) facies containing redeposits (R) facies containing calcrete-redeposits (RC) facies containing Rosselia socialis (RS) facies with clastic dykes (CD) The heterolithic tidal bedding facies (t) and the nodular facies (NS) occur exclusively in the ldquozone of the delta faciesrdquo (see Fig 3) whereas the further facies types can also be found in other parts of the marine succession The nodular facies was detected in the Lecken-bach section at the base of the ldquozone of the delta faciesrdquo and in the Huberbach section the heterolithic tidal bedding and planar barrier cross-bedding are well developed in the Kes-selbach section In the latter section sandstones of the hetero-lithic tidal bedding facies show fl ute and load casts at their subfaces (Fig 5F) indicating a southwestward current direc-tion Planar barrier cross-bedding is well developed at the beginning of the tide-dominated part of the Kesselbach sec-tion There an approximately 05 m thick layer of cross-bedded sandstones is composed of planar foreset laminae dip-ping to the SE (Fig 5G) This characteristic bed wedges out to the NW where it interfi ngers with a conglomerate layer

Sedimentary environmentAccording to the terminology of Nemec (1990) and Postma (1990) the Pfaumlnder delta as a whole may be interpreted as an alluvial fan delta characterised by a small delta plain a steep slope with deep channels and a direct transition to the shore-face The coarse-grained sediments and many of the sedi-mentary structures of the ldquozone of the delta faciesrdquo indicate a high-energy system of a prograding delta complex in front of the Pfaumlnder Fan

The FC conglomerate most likely represents the coarse-grained channel fi lls of the steep delta slope that were fed by the alluvial fan (cf Schaad et al 1993) The decreasing thick-ness of the ldquoKanzelfels-Nagelfl uhrdquo ldquoGebhardsberg-Nagel-fl uhrdquo and of the basal conglomerate from SW to NE and the fi nal disappearance of these channel deposits northeast of the Leckenbach section indicates that the talus centre was lo-cated near Bregenz in the Southwest

The MC type conglomerate shows a marine genesis and resembles the ldquoBryozoensandsteinrdquo in the Upper Marine Molasse farther to the East in the area of Kempten (Scholz 1989 Scholz amp Bienerth 1992) The ldquoBryozoensandsteinrdquo is more fi ne-grained but principally represents the same type of limestone with sand and pebbles as the MC type conglo-merates These sediments can be interpreted as beach ridge deposits (see also Guumlmbel 1894 284 Scholz amp Bienerth 1992) deposits of rip channels or as storm sand lobes in the foreshore or upper shoreface

In the Leckenbach and Rothenbach sections the MC conglomerates contain crystalline components (see above) which are normally absent in the deltaic Pfaumlnder sediments (Schiemenz 1960 Scholz 2000) To the East of the Pfaumlnder Fan is the Hochgrat-Adelegg Fan to the West the Houmlrnli Fan (Fig 2) The deltaic conglomerates of both fans are rich in central Alpine crystalline pebbles with a share of 6 to 11 in the Hochgrat-Adelegg Fan (Schiemenz 1960 Jerz 1974 Eberhard 1986) and a portion of approximately 15 in the Houmlrnli Fan (Hottinger et al 1970) The Hochgrat-Adelegg conglomerates exclusively contain metamorphic pebbles (Schiemenz 1960 Eberhard 1986 Scholz 2000) whereas the Houmlrnli conglomerates contain metamorphic pebbles gran-ites and other plutonic rocks As the MC type conglomerates of the Leckenbach and Rothenbach sections contain only pebbles of metamorphic rocks and no plutonites they should have been derived from the Hochgrat-Adelegg Fan In con-trast to the derivation of the crystalline pebbles in the ldquobasalrdquo conglomerate with a fl uvial habitus a likely explanation for these pebbles in the MC conglomerates is longshore drift from east to west (Scholz 2000)

The heterolithic tidal bedding facies (t) can be inter-preted as deposits of an intertidal fl at (cf Schaad et al 1992) deposited on the delta plain The orientation of fl ute casts in the heterolithic facies of the Kesselbach section supports southward running currents (compare Bieg et al 2008) If the coastal environment near the southern coast of the Mo-lasse Sea had a rather simple tidal current regime this domi-nant southward oriented current direction could be inter-preted as fl ood currents (as the mainland is located to the South)

The nodular sandstone facies (NS) mainly refl ects a dia-genetic effect The originally ripple-bedded or bioturbated sandstone beds obviously were selectively overprinted by diagenesis to form nodular structures It can be assumed that this facies type originally was a heterolithic facies with thin marly layers and thick sandstone beds with ripple cross-bed-ding and double mud drapes The latter support a subtidal environment

424 The ldquozone of marls and fi ne-grained sandstonesrdquo

Previous studiesThe marly sediments of the upper part of the Wirtatobel sec-tion have been interpreted as muddy background sedimenta-tion in the transition zone towards the offshore area by Schaad et al (1992) According to these authors this part of the succession accumulated when the sea of the Upper Ma-rine Molasse had attained the ldquophase of the maximum trans-gressionrdquo

DescriptionThe upper parts of the Leckenbach and Huberbach sections and also of the Wirtatobel section (see Fig 9) are built up of 60 to more than 80 m thick marly deposits (facies type SM Fig 6A) They are fi nely layered often bioturbated and con-tain thin sandy intercalations Within these marly background sediments more coarse-grained material of storm beds (facies



type T) forms thin but distinct layers To the NE in the Kes-selbach and Rothenbach sections the marly deposits are sub-stituted by fi ne-grained glauconitic sandstones with a thin-platy structure comparable to the ldquozone of the glauconitic sandstonesrdquo (Fig 6B) Higher up in the section conglomer-atic layers occur in the Leckenbach section and sandy inter-calations increase in the other sections (see Fig 3)

Depositional environmentThe marly deposits in the southwestern area (Wirtatobel Leckenbach Huberbach) indicate a decreasing activity of the delta and a quiet and comparatively deepened environ-ment (confi rmed by microfossils see chapter 5 and table 1) of a muddy prodelta in an open marine bay More coarse-grained material obviously attained this area only by episodic events like storms (facies type T) The co-occurrence of marls and storm beds indicates the transition zone as likely environment (see Aigner amp Reineck 1982)

In the distal northeastern sections (Kesselbach Rothen-bach) the glauconitic fi ne-grained sands (which here replace the marls of the southwestern sections) indicate a shoreface environment with a slightly higher energy This may point to a temporal or local break-down of the fl uvial input in this

area which led to the development of barrier islands and sand bars consisting of sands from the delta plain (cf Schaumlfer 2005)

425 The ldquoWirtatobel coal seamrdquo and further coal layers

Previous studiesIn the area between Bregenz and the Wirtatobel section the ldquozone of the delta faciesrdquo bears a 28ndash40 m thick limnic to brackish marl succession with freshwater and land gastro-pods freshwater bivalves brackish microfaunas and calcrete (Blumrich 1930 Wenz 1933 Resch 1977 Schaad et al 1992) which separates the lower two thirds of the Upper Marine Molasse from the upper third It contains an up to 70 cm thick detrital coal layer consisting of several closely spaced thin coal seams (eg Guumlmbel 1861 765 1887 258 1896 Ploumlchinger et al 1958 Steininger et al 1982) Schmidt amp Muumlller (1911) and Jaumlger (1957) suggest an extension of 7 x 2 km This ldquoWirtatobel coal seamrdquo and the hosting marls apparently represent a brackish to limnic interval between two marine ldquoingressionsrdquo (Guumlmbel 1896 Heim et al 1928 Wenz 1933 1935 Keller 1989) Schaad et al (1992) de-scribed a ldquofi rstrdquo and a ldquosecond terrestrial horizonrdquo in the ma-rine Pfaumlnder succession between Bregenz and the Wirtatobel (see Fig 9) They termed the limnic-brackish deposits with the ldquoWirtatobel coal seamrdquo ldquosecond terrestrial horizonrdquo It serves as a marker horizon which allows for separating the Luzern Formation (below) from the St Gallen Formation (above) Also it can be correlated with the ldquofl uvioterres-trischer Zwischenkomplexrdquo (Renz 1937 Buumlchi amp Hofmann 1945) in the St Gallen region (Hofmann 1997) A wedging out of the Wirtatobel coal seam to the Northeast (see Herr-mann et al 1985) and to the West is known from mining ac-tivities (Fig 7) According to Resch (1977) the coal seam developed in the talus centre of the Pfaumlnder Fan because of a short-termed local emersion of the deltaic deposits Guumlmbel (1896) assumed that the coal was a freshwater horizon de-posited in a small local basin near Bregenz

The ldquoWirtatobel coal seamrdquo is the most important coal deposit in the Molasse of Vorarlberg (Weber amp Weiss 1983 Herrmann et al 1985) and one of the biggest coal deposits in the western Molasse

Further coaly intercalations have been described from other stratigraphic positions Herrmann et al (1985) men-tioned a 20 to 40 cm thick coal seam in a higher stratigraphic position Guumlmbel (1896) found a thin coal layer about 85 m above the mined Wirtatobel seam which he parallelised with a seam in the Kesselbach section (Erb 1922 Herrmann et al 1985) This particular seam in the Kesselbach section marks the transition to the Upper Freshwater Molasse (Appel 1992 Kanzock 1995)

DescriptionNumerous coal fragments can be found in the tributary val-ley of the Wirtatobel near the old coal mines which obvi-ously belong to the classical ldquoWirtatobel coal seamrdquo but the coal seam itself does not crop out at present The coal slabs

Fig 6 (A) Marls of the facies type shelf mud (SM Leckenbach section) with an intercalated tempestite sandstone bed of the facies type T (centre of the picture) (B) Thin-platy sandstones (facies type GS) in the upper part of the Kesselbach section

Abb 6 (A) Schelfmergel (SM Leckenbach-Profi l) mit einer einge-schalteten Tempestitbank T (Bildzentrum) (B) Duumlnnplattige glau-konitische Sandsteine (GS) im oberen Abschnitt des Kesselbach-Profi ls



are up to 15 cm thick partly laminated and bear intercala-tions of bituminous sandstone They consist of plant detritus carbonised wood pieces fl attened gastropods sand mica and clay In contrast to all previous studies (Guumlmbel 1896 Blumrich 1930 and various expert opinions for the coal min-ing) the coal from Wirtatobel as well as from Kesselbach is not vitrain but lignite Own studies (results not published yet) have shown that the degree of carbonisation is only 036 Rr Although the studied sections are nearly continu-ously exposed (see Fig 3) a coal seam or coal layer in a stratigraphic position similar to the Wirtatobel coal was not detected However coal fragments with diameters up to 50 cm were found as components of a 25 m thick breccia (Fig 8A) in the middle of the Kesselbach section (facies type RC) and thus in a lithostratigraphical position compara-ble to the Wirtatobel coal Besides the coal fragments the breccia contains mainly whitish carbonate clasts and some

marine fossils (bivalves fi sh remains) in a matrix of glauco-nitic sandstone The partly laminated coal slabs represent fragments of a detritical coal seam and show the same com-position and characteristics as described above for the Wirta-tobel coal The whitish carbonate clasts consist of micritic limestone are subrounded and partly broken They are re-worked nodular carbonate concretions or fragments of nod-ules with an indistinct internal concentric layering as well as calcite-fi lled shrinking fi ssures which are typical for pedo-gene calcretes (Fig 8B)

Furthermore the above mentioned coal seam that marks the beginning of the OSM is well exposed in the Kesselbach section (Fig 8C) It consists of two 3ndash4 cm thick coal layers intercalated in grey marls and bearing small planispiral freshwater gastropods

Sedimentary environment of the coal layersGenerally the coals indicate periods of local freshening on the delta plain The prominent ldquoWirtatobel coal seamrdquo appar-ently represents the longest period of freshening The cal-cretes and coal bearing reworked layer of the Kesselbach section which can be interpreted as time-equivalent to the Wirtatobel coal support the presence of terrestrial areas lo-cated in the vicinity Calcretes have also been described from the marly succession in which the ldquoWirtatobel coal seamrdquo is embedded (ldquosecond terrestrial horizonrdquo Schaad et al 1992) Thus it can be assumed that the ldquoWirtatobel coal seamrdquo and its equivalents indicate a period of freshening non-deposi-tion and process of alluviation including the development of soils It is likely that the calcrete and peat were eroded from such areas of the delta plain by energy-rich events ie storms and redeposited in the northeastern adjacent marine environment Other sources for the calcrete are unlikely The calcrete sediments that are known from the Upper Freshwa-ter Molasse of the Pfaumlnder area (Elsner 2006) are too young Other occurrences of calcrete in the Southwest German part of the Molasse Basin like the ldquoAlbsteinrdquo (see Lemcke et al 1953 Naumlgele 1962 Reichenbacher 1993) or calcretes in the Upper Freshwater Molasse (Scholz 1986) are also too young and too distant

In summary the four sections to the NE of the Wirtatobel represent continuous marine successions without any indica-tions of a freshening or process of alluviation Thus the ter-restrial part of the delta plain apparently was restricted to the very centre of the deltaic complex in the Wirtatobel area

5 Biostratigraphy and palaeoecology

51 Previous studies

The biostratigraphy of the Upper Marine Molasse in the South German part of the Molasse Basin is mainly based on benthic foraminiferal assemblages and index species (Hagn 1959 1961 Knipscher 1952 Wenger 1987a b Pippegraverr et al 2007a b Pippegraverr amp Reichenbacher 2009) These studies which mostly have focused on the sediments in the eastern part of the basin (east of Munich) have shown that abun-

Fig 7 (A) Photograph from the Wirtatobel mine of the 1920s (source archive of the municipality LangenVorarlberg) (B) An old adit entrance above LangenVorarlberg little west of the Lecken-bach section built by tidal bedded sandstones (facies type t)

Abb 7 (A) Stolleneingang Minengebaumlude und Belegschaft des Bergwerkes am Wirtatobel in den 1920er Jahren (Quelle Archiv der Gemeinde LangenVorarlberg) (B) Alter Stolleneingang ober-halb LangenVorarlberg etwas westlich des Leckenbaches Er befi n-det sich in Gezeiten-Sedimenten (Faziestyp t)



dances and diversities of species decrease continuously from the Eggenburgian to the Early Middle and Late Ottnangian Index fossils are present during the Eggenburgian and Early Ottnangian whereas the biostratigraphy of the Middle and Late Ottnangian is based on the appearance and abundance of characteristic foraminiferal assemblages In addition also bivalves can be used for the biostratigraphy of the Upper Marine Molasse (Piller et al 2007)

As mentioned above the marine succession of the Wirta-tobel section was subdivided in the Luzern Formation and the overlying St Gallen Formation with the coal seam and ac-companying freshwater sediments indicating the boundary between them Foraminifera have provided an Upper Eggen-burgian age for the Luzern Formation ie for the succession between the bottom of the ldquoKanzelfels-Nagelfl uhrdquo and the coal seam (Herrmann amp Schwerd 1983 Wenger 1987b) An Eggenburgian age was additionally supported by nannoplank-ton (zone NN3) for the succession between the ldquoKanzelfels-Nagelfl uhrdquo and the ldquoGebhardsberg-Nagelfl uhrdquo (Resch 1977 Roumlgl amp Steininger 1983) Also gastropods and bivalves (from the Kesselbach section) below the position of the coal seam specify an Eggenburgian age Gastropods and bivalves from the Wirtatobel sediments above the coal seam point to a Lower Ottnangian age (Sieber 1959) However the most precise bi-ostratigraphy was achieved on the basis of benthic foramini-fera (Wenger 1987b) Accordingly the boundary between the Eggenburgian and Ottnangian appears in the lower part of the St Gallen Formation shortly above the ldquoWirtatobel coal seamrdquo and its equivalents (Wenger 1987b)

52 This study

The data concerning the foraminifera are kindly provided by Martina Pippegraverr Generally the preservation of the foramini-fera was poor In the Leckenbach section marly layers of the ldquozone of the delta faciesrdquo (4 samples) and ldquozone of marls and fi ne-grained sandstonesrdquo (8 samples) have yielded foramini-fers (for the position of the samples see fi gure 3) The lower-most sample ldquoardquo includes a foraminiferal assemblage with a relative high diversity (Tab 1) which points to shallow ma-rine (neritic) conditions With the exception of sample ldquoordquo at the basis of the ldquozone of marls and fi ne-grained sandstonesrdquo marine species are rare in all other samples and point to very shallow water and possibly brackish conditions However sample ldquoordquo contained a comparatively species-rich fo-raminiferal assemblage in which keeled species of Elphid-ium (eg Elphidium subtypicum) Nonion or Cibicides as well as planktonic globigerinids are most abundant thus supporting comparatively deep water and normal marine conditions (Murray 2006 see Tab 1) As the overlying sam-ples are again poor in foraminiferal species and individuals the deep water environment obviously was only short in du-ration The uppermost sample ldquolrdquo directly below the bottom of the OSM conglomerates contains only Ammonia which suggests a brackish infl uence

The Huberbach section to the Northeast shows a similar assemblage of foraminifera like the Leckenbach (Tab 1) Five samples were taken from the ldquozone of the delta faciesrdquo and two from the ldquozone of marls and fi ne-grained sandstonesrdquo (see

Fig 8 (A) Detail of the reworked calcrete layer (RC) in the Kesselbach section show-ing small white calcrete fragments and big pieces of coal (arrows) (B) Thin section of a calcrete pebble with shrinking fi ssures (C) Thin coal seams in the upper part of the Kes-selbach section mark the beginning of the Upper Freshwater Molasse succession

Abb 8 (A) Ein Ausschnitt aus der Aufarbei-tungslage (Faziestyp RC) im Kesselbach-Profi l zeigt ihre hauptsaumlchliche Zusammen-setzung aus kleinen weiszligen Calcrete-Bruch-stuumlcken und groszligen Kohlestuumlcken (Pfeile) (B) Duumlnnschliff eines Calcrete-Geroumllls mit Schrumpfrissen (C) Duumlnne Kohlefl oumlze im oberen Teil des Kesselbach-Profi ls markie-ren den Beginn der Oberen Suumlszligwassermo-lasse



Tab 1 Microfossils in the ldquozone of the delta faciesrdquo and the overlying ldquozone of marls and fi ne-grained sandstonesrdquo (zms) in the Leckenbach and Huberbach sections For the position of the samples see fi gure 3 a = 1 individual b = 2ndash5 individuals c = 6ndash20 individuals d = gt 20 individuals br = brackish m = marine com = common

Tab 1 Mikrofossilien der Fazieseinheiten bdquoZone der Delta-Faziesldquo und der sie uumlberlagernden bdquoZone der Mergel und Feinsandsteineldquo in den Profi len Leckenbach und Huberbach Die Lage der entnommenen Proben im Profi l ist Abbildung 3 zu entnehmen a = 1 Individuum b = 2ndash5 Individuen c = 6ndash20 Individuen d = gt 20 Individuen br = brackisch m = marin few = selten com = haumlufi g

Leckenbach HuberbachSample numberdelta facies zone of marls and fine-grained sandstones delta facies zms

a m t n o h i j q s r l g n l m a e fm br to m m br to m m b m br to m Salinityb c a a Elphidium glabratum CUSHMAN

ad

Elphidium macellum (FICHTEL amp MOLL)

b cb a Elphidium subtypicum PAPP

a Elphidium matzenense PAPP

c a Elphidiella minuta (REUSS)b c a a b a Ammonia beccarii (LINNEacute) sl

b aCibicides lobatulus (WALKER amp JACOB)

c cCibicidoides lopjanicus (MYATLYUK)

b b Hanzawaia boueana (Drsquo ORB)a d b Globigerina spp

c a a a Elphidium sppa Textularia spa Bulimina elongata Drsquo ORBa Polymorphinidaec a b Nonion commune (Drsquo ORB)a Cibicidoides tenellus (REUSS)c a Cibicididae

a Cibicidoides spc Bolivina sppa Discorbis sp

bSiphonodosaria aff verneuili (Drsquo ORB)

b Elphidium sp (keeled)a Pullenia bulloides (Drsquo ORB)

a Lagena striata (Drsquo ORB)

bForaminifera indet (poor preservation)

a Radiolariaa d b a b b a few b b b Ostracoda

com Balanomorphafew com Bryozoa

b a Polychaetaa a b Gastropoda

few a few few few few com com few few Echinoid-spinesa a Fish tooth

few a few few Shell fragmentsb b Bones

May be redeposited from Flysch sediments and partly from the Upper Austroalpine (see Resch 1977)



Fig 3) Only the lowermost sample ldquogrdquo (ldquozone of the delta faciesrdquo ie a comparable position as sample ldquoardquo in the Lecken-bach section) has yielded a foraminiferal assemblage with sev-eral species which point to shallow but normal marine condi-tions All other samples contain poor foraminiferal assemblages (see Tab 1) The same was true for further samples from the Kesselbach and Rothenbach sections which did not contain any determinable microfauna

The tiny spines of irregularia (see Tab 1) in most of the samples indicate a not to low salinity in this marginal marine environment

The foraminiferal data from the Leckenbach and Huber-bach sections do not allow a precise biostratigraphy The stratigraphic distribution of Elphidium subtypicum Papp present in the Leckenbach section (see Tab 1) is Eggenbur-gian to Karpatian (Wenger 1987a Cicha et al 1998) Elphid-ium glabratum Cushman which was found in both studied sections is abundant in the Lower and Middle Ottnangian in Eastern Bavaria but rarely occurs also in the Eggenburgian and Upper Egerian (Wenger 1987a Pippegraverr amp Reichenbacher 2009)

6 Sequence stratigraphy of the Pfaumlnder alluvial fan-delta

As the sequence stratigraphical concept is developed for ma-rine deposits at passive continental margins its application for epicontinental successions like the Upper Marine Mo-lasse bears some diffi culties In epicontinental basins sys-tems tracts and sequence boundaries may not be developed clearly the typical lowstand systems tract is missing and the eustatic effects may be obscured by climate tectonics sub-sidence and compaction (Aigner et al 1999) Despite these uncertainties we here attempt a sequence stratigraphical in-terpretation of the Pfaumlnder alluvial fan-delta based on rela-tive sea-level changes (changes in base level) The relative sea-level refers to fl uctuations in the Pfaumlnder delta area whereas the Parathetys sea-level is considered as the refer-ence level However the Paratethys sea-level does not nec-essarily refl ect the global eustatic sea-level as it is likely that eustatic changes did not reach the Paratethys interior basin so far (Bieg et al 2008)

We determined two large-scale transgressive-regressive sequences (Fig 9) each is composed of a transgressive sys-tems tract (TST) and a highstand systems tract (HST) Sub-ordinated cycles are described in terms of base level varia-tion (Cross amp Lessenger 1998) Altogether fi fe base level cycles (cycles IndashV) have been detected within the Upper Ma-rine Molasse succession investigated here based on shallow-ing or deepening trends in depositional facies The interpre-tation of sequences and systems tracts is based on these base level cycles

61 Sequence 1

The Upper Marine Molasse succession starts with marine sediments unconformable over terrestrial deposits of the Lower Freshwater Molasse pointing to an initial transgres-sion It provided an important basal boundary in the sense of a sequence boundary Locally the ldquobasal conglomeraterdquo of Wirtatobel Leckenbach and Huberbach which are inter-preted as fl uvial channel fi lls (Fig 11) is characterised by a prominant erosional surface These fl uvial channels bounded by regional unconformities at the base are interpreted as chan-nel fi lls while the base level was low (Miall 1992) Thus the ldquobasalrdquo conglo-merate marks the start of the fi rst base level cycle (cycle I) also the superordinate TST (Fig 9) However the erosion channels have been developed before and mark the lowstand systems tract (not shown in fi gure 9)

The beginning of a TST is usually marked by coarse-grained sediments termed as ldquobasal conglomeraterdquo or ldquotrans-gression conglomeraterdquo The conglomerates derive from re-working of the fl ooded surfaces of strand plains (Schaumlfer 2005) However the existence of a ldquobasal conglomeraterdquo de-pends on the rate and energy of the fl ooding and reworking respectively On delta plains the transgression may take place without reworking and terrestrial deposits may be di-rectly overlain by fi ne-grained marine deposits (Schaumlfer 2005) In the marine Pfaumlnder succession a ldquotransgression conglomeraterdquo or other basal reworking sediments are miss-ing Instead fi ne-grained clastic deposits (facies type GS) directly rest on terrestrial sediments of the Lower Freshwater Molasse (Kesselbach Rothenbach) Locally (Leckenbach Huberbach) the above mentioned fl uvial ldquobasal conglomer-aterdquo is intercalated Due to its fl uvial origin it is considerd not to be a genetic equivalent of a ldquotransgression conglomer-aterdquo although it is clearly marine It most likely refl ects the initial activity of the Pfaumlnder delta evolving later in time

The lower part of the ldquozone of glauconitic sandstonesrdquo represents a base level rise (lower part of cycle I) forming the upper part of the transgressive systems tract (TST Fig 9) A marine maximum fl ooding surface (mfs) marks the start of the base level fall hemi-cycle of base level cycle I and also the initiation of the following HST

The position of the maximum fl ooding surface (mfs) can-not be defi ned exactly (see dotted line with a question mark

Fig 9 Simplifi ed sections of the Pfaumlnder succession (this study and Schaad et al 1992) including lithocorrelation sequence strati-graphic interpretation and mapping of parallelizable main facies (dark grey = deltaic medium grey = nearshore sandy light grey = open marine muddy) For the position of the cross-sections (AndashArsquo BndashBrsquo) see fi gure 1D

Abb 9 Vereinfachte Darstellung der Pfaumlnder-Profi le (eigene Auf-nahmen und Schaad et al 1992) mit der Korrelation lithologischer Einheiten sequenzstratigrafi scher Interpretation und Darstellung der Haupt-Fazieseinheiten (dunkelgrau = deltaisch mittelgrau = kuumlstennah sandig hellgrau = offen marin mergelig) Die Lage der Schnittlinien (AndashArsquo BndashBrsquo) ist Abbildung 1D zu entnehmen





in fi gure 3) It is marked by the occurrence of a mudstone horizon at least in one of the sections (Huberbach section) Consequently we consider the upper part of the glauconitic sandstones zone as part of the following highstand systems tract (HST) signalling the progradation of the shoreface The ldquozone of the delta faciesrdquo (base level cycles II and III) is in-terpreted as forming the upper part of this highstand systems tract (HST Fig 9) which is characterised by a general base level fall a prograding shoreface (deltafront facies) and the conglomerates deposited on the deltaplain The erosive bases of the conglomerates indicate boundaries of subordinated or-der within this HST

Moreover in this context the ichnohorizon with Rosselia socialis in the Kesselbach section (Frieling 2007) most likely refl ects the mfs in base level cycle II In all the ldquozone of the delta faciesrdquo (upper part of HST) ndash subdivided into two base level cycles (II and III as refl ected by the two distinct con-glomerates see Figs 3 9) ndash shows individual offl ap and on-lap trends within the delta It is diffi cult to decide whether these base level cylces result from fl uctuations of the Para-tethys sea level or from variations in fl uvial input of subsid-ence and compaction probably all these factors have to be taken into account

Nevertheless the base level cycles seem to correlate with the Paratethys sequences of Hardenbol et al 1998 (see Fig 10) Base level cycle I correlates with Aq-2 representing the initial fl ooding of a primary relief with a possible palaeo-high in the Rothenbach area (considered that the missing rise hemi-cycle of base level cycle I there will not only be the result of non-exposure) In the proximal sections basal chan-nel fi lls seem to anticipate the development of deltaic activ-ity later in this area Base level cycle II seems to correlate with Aq-3Bur-1 (Hardenbol et al 1998 see Fig 10) and marks the incipient deltaic activity of the Pfaumlnder delta and

probably also of the Hochgrat delta which most likely infl u-enced the northeasternmost section (Rothenbach see chapter 423) Base level cycle III is correlated with Bur-2 (Harden-bol et al 1998 see Fig 10) and refl ects the culmination of the deltaic activity Finally reduced water depth and partly subaerial exposition are represented by terrestrial deposits in the uppermost part of the delta plain complex (base level fall of cycle III) occurring in the second ldquoterrestrial horizonsrdquo (see Schaad et al 1992) in the talus centre

62 Sequence 2

Sequence 2 is composed of two base level cycles (cycles IV and V Figs 3 9 10) It starts with a conglomerate forming the rise of base level cycle IV together with the lowermost marlstones of the ldquozone of marls and fi ne-grained sand-stonesrdquo This rise hemi-cycle also represents the TST of this sequence The main part of the ldquozone of marls and fi ne-grained sandstonesrdquo marks a fall of base level in cycle IV Compared with the sequence 1 foraminiferal data (sample ldquoordquo) indicate a general deepening of the water Together with corresponding lithofacies types (T SM) they support the as-sumption of an overall rising relative sea-level most likely caused by decreasing deltaic activity (Fig 11) The environ-ment may have been a wide and open marine bay or a prodelta environment Deltaic foresets (sandstones and marls with thin conglomeratic intercalations) in proximal sections and sandy intercalations (shoreface sandstones) in distal sections indicate the HST and a shallowing tendency respectively However the HST is not as prominent as the HST of the se-quence 1 Base level cycle IV is correlatable with Bur-3 (Hardenbol et al 1998 see Fig 10) and refl ects the drown-ing of the delta (Fig 11) A last short deepening phase is de-

Fig 10 Chronostratigraphic intepretation of the base level cycles and sequences of the Pfaumlnder succession Miocene geochronology after Lourens et al (2004) correlation of Central Paratethys stages after Harzhauser amp Piller (2007) global sequence stratigraphy after Hardenbol et al (1998) regional lithostratigraphy in the Pfaumlnder region after Schaad et al (1992) and in the ldquoWestmolasserdquo after Doppler et al (2005)

Abb 10 Chronostratigrafi sche Einstufung der bdquobase-levelldquo-Zyklen und Sequenzen in der Pfaumlnder-Abfolge Stratigra-fi sche Gliederung des Miozaumlns nach Lourens et al (2004) Korrelation mit den Einheiten der zentralen Paratethys nach Harzhauser amp Piller (2007) globale Sequenzstratigrafi e nach Hardenbol et al (1998) regionale Lithostratigrafi e am Pfaumln-der nach Schaad et al (1992) und in der bdquoWestmolasseldquo nach Doppler et al (2005)



tectable within the top of sequence 2 (indicated by fi ning-upward tendencies) and refl ects a small fl uctuation of the relative sea-level which can be interpreted as rise hemi-cy-cle of a last base level cycle (V) Its fall branch is most likely suppressed by erosion (see Figs 3 9 10) This last small base level cycle has no equivalent in the 3rd-order sequences

of Hardenbol et al (1998 see Fig 10) probably it refl ects a local development

The top of sequence 2 is cut by a sharp erosional surface and overlain by thick coarse-grained alluvial conglomerates of the Upper Freshwater Molasse (OSM see Fig 9) This erosional surface represents a signifi cant sequence boundary and points to a rapid fall of the relative sea-level and a quick process of alluviation This sea-level fall probably can be parallised with the sequence boundary between Bur-3 and Bur-4 (Hardenbol et al 1998) at 17235 Ma at the end of the Ottnangian (Fig 10)

63 Sequence stratigraphic studies in other parts of the basin

First ideas on sequence stratigraphy concerning a subdivi-sion of the Upper Marine Molasse in the South German part of the Molasse Basin were presented by Lemcke et al (1953) who recognised two transgressive-regressive cycles in the so-called ldquoWestmolasserdquo (west of Munich) Since then mod-ern sequence stratigraphical studies in the South German part of the Molasse Basin were done mainly in the ldquoOstmo-lasserdquo (east of Munich) on the basis of seismic lines and well logs (see Jin 1995 Zweigel 1998 Pentildea 2007) A single seis-mic line with rather poor quality was studied in the ldquoWest-molasserdquo (west of Munich Pentildea 2007)

In the ldquoWestmolasserdquo the Alpine Molasse succession is built of two transgressive-regressive mega-sequences ie the Lower Marine and Lower Freshwater Molasse and the Upper Marine and Upper Freshwater Molasse This compo-sition is different from the ldquoOstmolasserdquo as there the Lower Freshwater Molasse had not been developed In the ldquoOstmo-lasserdquo Jin (1995) and Zweigel (1998) recognised three ma-jor trangressive-regressive depositional cycles which are separated by three transgression surfaces and consist of fi ve depositional sequences of second order (sequences 1 to 5 see Fig 12) Pentildea (2007) was able to identify the same fi ve seismic sequences in the ldquoWestmolasserdquo

According to these former studies the Upper Marine Molasse was deposited during the transgression of the third megacycle and belongs to the second order sequence 4 (see Fig 12) Also the Aquitanian Fish Shales (which are under-lying the Upper Marine Molasse) were included in the se-quence 4 they are overlying a type 1 unconformity indicat-ing a sea-level fall (Jin 1995 Zweigel 1998) Jin (1995) con-cluded that the Aquitanian Fish Shales represent the LST Neuhofen Schichten and its equivalents form the TST and the higher parts of the Ottnangian developed during the HST This means that the complete succession of the Upper Ma-rine Molasse (ie the Neuhofen Schichten and the overlying Ottnangian strata) would represent a part of a single second order sequence However in the sea-level curve given by Haq et al (1987) and also discussed by Jin (1995) a distinct transgression is evident in the Early Ottnangian which cor-responds to the Neuhofen Schichten Although Jin (1995) noticed that ldquothe lower part of the Helvetian (Neuhofen Schichten) corresponds to a new transgressionrdquo he did not

Fig 11 The development of the marine Pfaumlnder succession in a sche-matic sketch From (A) to (C) the Paratethys sea-level rises (A) Start of base level cycle I (Eggenburgian) with the deposition of the basal conglomerate (B) The fall of base level cycle III (boundary Eggen-burgianOttnangian) refl ects the culmination of deltaic activities the strong deltaic input results in local terrestrial environments (forma-tion of the Wirtatobel coal at the delta plain) (C) Base level cycle IV (Ottnangian) drowning of the delta in distal areas (Rothenbach sec-tion) probably a deltaic input of the Hochgrat-Adelegg Fan results in the development of barrier islands W = Wirtatobel section L = Leck-enbach section R = Rothenbach section

Abb 11 Die Entwicklung des Pfaumlnder-Deltas in einer schema-tischen Skizze Der Paratethys-Meeresspiegel steigt von (A) nach (C) an (A) Beginn des ldquobase-levelldquo-Zyklus I (Eggenburg) mit der Ablagerung des bdquoBasalkonglomeratsldquo (B) Die Absenkung des bdquobase-levelldquo-Zyklus III (EggenburgOttnang-Grenze) spiegelt den Houmlhepunkt der Delta-Aktivitaumlt wider der starke klastische Eintrag fuumlhrt lokal zur Verlandung (Bildung des Wirtatobel-Kohlefl oumlzes auf der Delta-Ebene) (C) bdquobase-levelldquo-Zyklus IV (Ottnang) Ertrinken des Deltas in distalen Regionen (Rothenbach) macht sich wahr-scheinlich der klastische Eintrag des Hochgrat-Adelegg-Faumlchers durch die Bildung von Barriere-Inseln bemerkbar W = Wirtatobel L = Leckenbach R = Rothenbach



consider this transgression in his sequence stratigraphic framework and did not discriminate subordinated sequences In contrast to this Zweigel (1998) and Pentildea (2007) found four or rather fi ve third-order sequences in the sequence 4 and interpreted the respective sequence boundaries as con-trolled mainly by ldquoeustaticrdquo sea-level falls (most likely refer-ring to the Paratethys sea-level) However the two superor-dinate sequences of the Pfaumlnder succession are diffi cult to compare with the fi ve sequences proposed by Pentildea (2007) due to the lack of biostratigraphic data

According to previous biostratigraphic data (Resch 1977 Herrmann amp Schwerd 1983 Roumlgl amp Steininger 1983 Wenger

1987b see chapter 5) sequence 1 of the Pfaumlnder area is Eg-genburgian in age while sequence 2 corresponds to the Ott-nangian The classical two transgressive-regressive ldquocyclesrdquo of the ldquoWestmolasserdquo (according to Lemcke et al 1953) are also Ottnangian in age (Wenger 1987b) As a result we sug-gest that sequence 2 of the Pfaumlnder with its two base level cycles (IV and V) can be correlated with these classical ldquocy-clesrdquo (see Fig 10) Further support for this assumption is provided by an overall shallowing tendency which can be recognised throughout sequence 2 and also in the classical cycles of Lemcke et al (1953) Moreover the relative thick-nesses of base level cycles IV and V of sequence 2 fi t well with those of the Lemcke cycles Lemcke et al (1953) have reported a thickness relation of 41 for their cycles which is consistent with the thicknesses of the base level cycles in sequence 2 Thus the classical two ldquocyclesrdquo of the German part of the Molasse Basin should be considered as time-equivalent to the Pfaumlnder base level cycles IV and V with the ldquoBasisschichtenrdquo and the ldquoSandmergelserierdquo corresponding to base level cycle IV and the ldquoBaltringer Schichtenrdquo and ldquoFeinsandserierdquo to base level cycle V (Fig 10)

However some differences appear with regard to the lithofacies and thicknesses (1) An equivalent of the coarse-grained ldquoBasisschichtenrdquo of the Westmolasse at the base of sequence 2 only exists in the southwesternmost section (Leckenbach section) (2) the relative thickness of the ldquoSand-mergelserierdquo is considerable higher than its equivalents at the Pfaumlnder (3) the ldquoBaltringer Schichtenrdquo are considerable thinner (see Heimann et al 2009) than the equivalents found here

7 Conclusion

The Upper Marine Molasse succession of the Pfaumlnder area together with the Upper Freshwater Molasse above form a transgressive-regressive sequence of second order which can be further subdivided into two transgressive-regressive sequences of superordinate order the sequences 1 and 2 de-scribed here (Fig 9) Compared with deposits of the same age from Lower Bavaria the whole Upper Marine Molasse succession in the Pfaumlnder area is poor in microfossils prob-ably due to high sedimentation rates in siliciclastics How-ever the sequence stratigraphical approach suggests that se-quences 1 and 2 correspond to the Luzern Formation (se-quence 1) and St Gallen Formation (sequence 2) described from the Wirtatobel (see Fig 9) and additionally correlate well with the sequences of the Houmlrnli delta and the Napf delta (Keller 1989) Moreover sequence 2 can be parallel-ised with the classical two ldquocyclesrdquo of the German part of the Molasse Basin (see Fig 10)

Sequence 1 and 2 of the Pfaumlnder area investigated (Fig 10) represent a general trend of a rising sea-level as the sedimentary facies of the ldquozone of marls and fi ne-grained sandstonesrdquo (TST of sequence 2 see Fig 9) point to a com-paratively deep environment (transition zone) whereas the sedimentary facies of the ldquozone of glauconitic sandstonesrdquo (TST of sequence 1 see Fig 9) was deposited in a more

Fig 12 Parallelisation of the results of this study with the sequence stratigraphic subdivisions of the Molasse given by Jin (1995) and Zweigel (1998)

Abb 12 Einordnung der Ergebnisse dieser Arbeit in die sequen-zestratigrafi sche Gliederung der Molasse nach Jin (1995) und Zweigel (1998)



shallow environment (between shoreface and transition zone) This is consistent with the trend of a generally rising sea-level as postulated by Zweigel (1998) for the Upper Ma-rine Molasse in Eastern Bavaria

We have regarded sequences 1 and 2 as sequences of su-perordinate order According to Zweigel (1998) eustasy (or better the Paratethys sea-level) is the prominent short-term factor that can cause rapid fl uctuations in the accommoda-tion space available in the Molasse Basin In this case changes of the Paratethys sea-level should present the main factor controlling sequences 1 and 2 However the record of seismites in the Kesselbach section (Scholz amp Frieling 2006) provides support for tectonic activity in the hinterland As these seismites appear in the upper part of the base level cy-cle I (see Fig 3) which is the lower part of the HST of se-quence 1 (= beginning of the deltaic succession see Fig 9) tectonic activity can be an additional factor for the prograda-tion of the Pfaumlnder delta

Sequences 1 (base level cycles I to III see Fig 3) and 2 (base level cycles IV and V see Fig 3) show considerable thickness variations throughout the studied sections This is mainly true for the sediments of the HST in sequence 1 These variations are most likely resulting from fl uctuations of both sediment input and accommodation space The Rothenbach section shows the lowest thicknesses for both sequences which may result from a decrease of fl uvial input due to the distal position or from the local topography ie presence of an island area or a palaeohigh

Furthermore we have shown that the ldquoWirtatobel coal seamrdquo well-known by mining activities does not represent a single coal layer Several coal seams in different stratigraph-ical positions were found within and at the top of the Upper Marine Molasse These coal seams may have formed due to several local freshenings on the delta plain of the talus cen-tre and the ldquoWirtatobel coal seamrdquo apparently represents the longest of these freshening periods The existence of rede-posited calcrete nodules co-occurring with the coal hints to climate conditions with mean temperatures between 14 and 18 degC (Hantke 1993 based on fl ora) and even temperatures more than 20 degC (Boumlhme 2003 based on ectothermic verte-brates Boumlhme et al 2007 based on wood) during the time-span of the Ottnangian and Karpatian Gregor (1979 based on the fl ora) reconstructed a Cfa-climate (humid subtropical climate with hot humid summers and chilly to mild winters) for the Upper Freshwater Molasse comparable with the cli-mate of Southern China of today having a very high precipi-tation rate However a strong seasonality with dry seasons continuing up to several months has been suggested for the Middle and Late Ottnangian on the basis of the ldquoAlbsteinrdquo lithofacies (Zoumlbelein 1985) isotopic analyses of fi sh otoliths (Reichenbacher et al 2004) and wood as well as soil analy-ses (Boumlhme et al 2007) The calcrete nodules thus well sup-port the presence of such seasonal differences during the Ott-nangian (Wright amp Tucker 1991)

Although the Paratethys sea-level probably does not re-fl ect the global eustatic sea-level sequence stratigraphic studies in Upper Marine Molasse successions are possible

which allow a correlation in the interior of the German part of the Alpine Molasse Basin

8 Acknowledgements

We would like to thank Beat Keller (Zuumlrich) and Hugo Ort-ner (Innsbruck) for their helpful comments during the fi eld-work We are indepted to Achim Wehrmann (Wilhelmshaven) for the invitation to ldquoSenckenberg am Meerrdquo in Wilhelms-haven where he patiently has helped to understand the depo-sitional processes of tidal infl uenced marine sediments We are grateful to Martina Pippegraverr (Munich) for the determina-tion of the foraminifera the stratigraphicalecological clas-sifi cation and for the critical comments on the palaeontolo-gical chapter as well as Wolfgang Witt for the identifi cation of the ostracods (Muumlnchen) We thank Jolanta Kus (Hanno-ver) for the determination of the coal We are grateful to the two reviewers Andreas Schaumlfer (Bonn) and J Georg Friebe (Dornbirn) for critical comments on the manuscript

9 References

Abele G Beschoren B Dehm R Erb L Fuchs B Ganss O Kiderlen H Nathan H Neumaier F Schmidt-Thomeacute P amp Stephan W (1955) Erlaumluterungen zur Geologischen Uumlber-sichtskarte der Suumlddeutschen Molasse 1 300 000 106 p Muumlnchen (Bayer Geol L-Amt)

Aigner T amp Reineck H-E (1982) Proximality trends in modern storm sands from the Helgoland Bight (North Sea) and their implications for basin analysis ndash Senckenb maritima 14 (5ndash6) 183ndash215 Frankfurt a M (Senckenb Naturforsch Ges)

Aigner T Hornung J Junghans W-D amp Poumlppelreiter M (1999) Baselevel cycles in the Triassic of the South-German Basin a short progress report ndash Zbl Geol Palaumlont Teil I 1998 537ndash544 Stuttgart (Schweizerbart)

Allen P Mange-Rajetzky M Matter A amp Homewood P (1985) Dynamic palaeogeography of open Burdigalian sea-way Swiss Molasse Basin ndash Eclogae Geol Helvetiae 79 351ndash381 Basel (Birkhaumluser)

Appel D (1992) Erlaumluterungen zur geologischen Karte des Ge-bietes suumldlich von Weiler im Allgaumlu ndash Diploma thesis Lehrst f Geol TU Muumlnchen 71 p Garching (unpubl)

Berger J-P Reichenbacher B Becker D Grimm M Grimm K Picot L Storni A Pirkenseer C Derer C amp Schaumlfer A (2005) Paleogeography of the Upper Rhine Graben (URG) and the Swiss Molasse Basin (SMB) from Eocene to Pliocene ndash Int J Earth Sci 94 697ndash710 Berlin (Springer)

Bieg U Suess MP amp Kuhlemann J (2008) Simulation of tidal flow and circulation pattern in the Burdigalian seaway (Upper Marine Molasse Early Miocene) ndash Spec Publ Int Assoc Se-dimentologists 40 145ndash169 Oxford (Blackwell)

Blumrich J (1908) Das Kohlenvorkommen im Wirtatobel bei Bregenz ndash 13 Jber d Bundesgymnasiums in Bregenz 19078 3ndash13 Bregenz

Blumrich J (1930) Die miozaumlne Molasse des Pfaumlnderstocks ndash Schr Ver Geschichte d Bodensees u seiner Umgebung 58 81ndash119 Friedrichshafen (Ver Geschichte d Bodensees u sei-ner Umgebung)



Blumrich J (1948) Die Wirtatobelkohle nach Beschaffenheit Vorkommen Entstehung und Abbau ndash Montfort Vierteljahres-schrift fuumlr Geschichte u Gegenwart Vorarlbergs 3 (2ndash6) 163ndash166 Dornbirn (Vorarlberger Verl-Anst)

Boumlhme M (2003) The Miocene climatic optimum evidence from ectothermic vertebrates of Central Europe ndash Palaeogeogr Pal-aeoclimatol Palaeoecol 195 389ndash401 Amsterdam (Else-vier)

Boumlhme M Bruch AA amp Selmeier A (2007) The reconstruction of Early and Middle Miocene climate and vegetation in South-ern Germany as determined from the fossil wood flora ndash Pa-laeogeogr Palaeoclimatol Palaeoecol 253 91ndash114 Amster-dam (Elsevier)

Buumlchi U amp Hofmann F (1945) Die obere marine Molasse zwi-schen Sitter-Urnaumlsch und dem Rheintal ndash Eclogae Geol Helve-tiae 38 (1) 175ndash194 Basel (Birkhaumluser)

Cicha I Roumlgl F Rupp C amp Ctyroka J (1998) Oligocene ndash Mio-cene foraminifera of the Central Paratethys ndash Abh sencken-berg naturforsch Ges 549 1ndash325 Stuttgart (Schweizerbart)

Cross TA amp Lessenger MA (1998) Sediment volume partition-ing rationale for stratigraphic model evaluation and high-reso-lution stratigraphic correlation ndash In Sandvik KO Gradstein F amp Milton N (eds) Predictive high resolution sequence stra-tigraphy ndash Norwegian Petroleum Soc Spec Publ 8 171ndash196 Amsterdam (Elsevier)

Doppler G Heissig K amp Reichenbacher B (2005) Die Gliede-rung des Tertiaumlrs im suumlddeutschen Molassebecken ndash Newsl Stratigr 41 (1ndash3) 359ndash375 Stuttgart (Schweizerbart)

Eberhard M (1986) Litho- und Biostratigraphie im Oberen Suumlszlig-wassermolasse-Faumlcher der Adelegg (Suumldbayern) ndash Jb geol B-Anst 129 (1) 5ndash39 Wien (Geol B-Anst)

Einsele G (2000) Sedimentary basins Evolution facies and sed-iment budget 2nd ed XI 792 p Berlin (Springer)

Elsner M (2005) Erlaumluterungen zur geologischen Karte von Scheidegg und Moumlggers Teil A ndashDiploma thesis Lehrstuhl f Ingenieurgeologie TU Muumlnchen 152 p Muumlnchen (unpubl)

Erb L (1922) Zur Stratigraphie und Tektonik der Allgaumluer Mo-lasse ndash Geognost Jh 35 167ndash192 Muumlnchen (Piloty amp Loehle)

Fahlbusch V (1981) Miozaumln und Pliozaumln ndash was ist was Zur Glie-derung des Jungtertiaumlrs in Suumlddeutschland ndash Mitt bayerische Staatsslg Palaumlont hist Geol 21 121ndash127 Muumlnchen (Baye-rische Staatsslg Palaumlont hist Geol)

Fischer H (1987) Excess K-Ar ages of glauconite from the Upper Marine Molasse and evidence for glauconitization of mica ndash Geol Rdsch 76 (3) 885ndash902 Stuttgart (Enke)

Frieling D (2007) Rosselia socialis in the Upper Marine Molasse of southwestern Germany ndash Facies 53 479ndash492 Berlin (Sprin-ger)

Fuumlchtbauer H (ed) (1988) Sedimente und Sedimentgesteine 4th ed 1141 p Stuttgart (Schweizerbart)

Gall H (1975) Der III Zyklus der Oberen Meeresmolasse (Hel-vet) am Suumldrand der Schwaumlbisch-Fraumlnkischen Alb ndash Mitt bay-erische Staatsslg Palaumlont hist Geol 15 179ndash205 Muumlnchen (Bayerische Staatsslg Palaumlont hist Geol)

Geyer OF amp Gwinner MP (1991) Geologie von Baden-Wuumlrt-temberg 482 p Stuttgart (Schweizerbart)

Gregor H-J (1979) Die jungtertiaumlren Floren Suumlddeutschlands 278 p Stuttgart (Enke)

Guumlmbel CW von (1861) Geognostischen Beschreibung des bay-erischen Alpengebirges und seines Vorlandes 20 + 950 p Go-tha (Perthes)

Guumlmbel CW von (1887) Die miozaumlnen Ablagerungen im oberen Donaugebiete und die Stellung des Schliers von Ottnang ndash Sitz-Ber bayerische Akad Wiss Muumlnchen math-physikal Kl 15 221ndash326 Muumlnchen (Bayerische Akad Wiss Muumln-chen)

Guumlmbel CW von (1894) Geologie von Bayern zweiter Bd Geo-logische Beschreibung von Bayern 1184 p Cassel (Theodor Fischer)

Guumlmbel CW von (1896) Das Vorkommen und der Bergbau terti-aumlrer Pechkohle im Wirtatobel bei Bregenz ndash Oumlsterreichische Z Berg- u Huumlttenwesen 44 115ndash121 Wien

Hagn H (1959) Die Gliederung der bayerischen Miozaumln-Molasse mit Hilfe von Kleinforaminiferen ndash Mitt oumlsterreichische geol Ges 52 133ndash141 Wien (Oumlsterreichische Geol Ges)

Hagn H (1961) Die Gliederung der Oberen Meeresmolasse noumlrd-lich vom Uumlberlinger See (Bodensee) in mikropalaumlontologischer Sicht ndash Jh geol L-Amt Baden-Wuumlrttemberg 5 293ndash321 Freiburg i Br (Geol L-Amt Baden-Wuumlrttemberg)

Hagn H (1992) Die Kreide- und Alttertiaumlrgeroumllle der Allgaumluer Molasse ndash ein Bruumlckenschlag zwischen Muumlnchen und Vorarl-berg Kurzfassung eines Vortrages ndash In Heinrich M (ed) Die Geologie von Vorarlberg Beispiel einer internationalen Zusam-menarbeit im Bereich der westlichen Ostalpen ndash Jb geol B-Anst 135 (4) 845ndash846 Wien (Geol B-Anst)

Hantke R (1993) Fluszliggeschichte Mitteleuropas Skizzen zu einer Erd- Vegetations- und Klimageschichte der letzten 40 Millio-nen Jahre 460 p Stuttgart (Enke)

Haq B Hardenbol J amp Vail PR (1987) Chronology of fluctua-ting sea-levels since the Triassic ndash Science 235 1156ndash1167 New York (American Assoc Advancement Sci)

Hardenbol J Thierry J Farley MB Jacquin T Graciansky P-C amp Vail PR (1998) Mesozoic and Cenozoic sequence chro-nostratigraphic framework of European basins ndash In Gra-ciansky C-P Hardenbol J Jacquin T amp Vail PR (eds) Mesozoic and Cenozoic sequence stratigraphy of European ba-sins ndash Soc Econ Paleontol Mineral Spec Publ 60 3ndash13 Tulsa (Soc Sediment Geol)

Harzhauser M amp Piller WE (2007) Benchmark data of a chan-ging sea ndash palaeogeography palaeobiogeography and events in the Central Paratethys during the Miocene ndash Palaeogeogr Pa-laeoclimatol Palaeoecol 253 8ndash31 Amsterdam (Elsevier)

Heim A Baumberger E Stehlin HG amp Fussenegger S (1928) Die subalpine Molasse des westlichen Vorarlberg ndash Viertel-jschr naturforsch Ges Zuumlrich 73 1ndash64 Zuumlrich

Heimann FUM Schmid DU Pippegraverr M amp Reichenbacher B (2009) Re-interpreting the Baltringer Horizont as a subtidal channel facies implications for a new understanding of the Up-per Marine Molasse ldquoCyclesrdquo (Early Miocene) ndash N Jb Geol Palaumlont Abh 254 135ndash149 Stuttgart (Schweizerbart)

Heinrich M (1980) Uumlbersicht uumlber die Braunkohlenvorkommen Vorarlbergs ndash Unpubl rep 40 p Wien (Geol B-Anst)

Herrmann P amp Schwerd K (1983) Geologische Karte der Repu-blik Oumlsterreich 1 25 000 ndash Erlaumluterungen zu Blatt 82 Bregenz 28 p Wien (Geol B-Anst)

Herrmann P Draxler I amp Muumlller M (1985) Geologische Karte der Republik Oumlsterreich 1 25 000 ndash Erlaumluterungen zu Blatt 83 Sulzberg 20 p Wien (Geol B-Anst)

Hofmann F (1997) Mineralische Rohstoffe und historischer Berg-bau rund um den Bodensee ndash Schr Ver Geschichte d Boden-sees u seiner Umgebung 115 169ndash191 Friedrichshafen (Ver Geschichte d Bodensees u seiner Umgebung)



Hottinger L Matter A Nabholz W amp Schindler C (1970) Er-laumluterungen zu Blatt 1093 Houmlrnli des Geologischen Atlas der Schweiz 1 25 000 31 p Bern (Kuumlmmerly amp Frey)

Jaumlger J (1957) Die Fatimakapelle bdquoAm Stollenldquo in Langen bei Bregenz ndash mit geschichtlichem Abriszlig uumlber die Gemeinde Lan-gen und das dortige Kohlebergwerk Wirtatobel 94 p Bregenz (Kirchbauver Bregenz)

Jerz H (1974) Geologische Karte von Bayern 1 25 000 Erlaumlute-rungen zu Blatt Nr 8327 Buchenberg 181 p Muumlnchen (Bayer Geol L-Amt)

Jin J (1995) Dynamic stratigraphy analysis and modelling in the south-eastern German Molasse Basin ndash Tuumlbinger geowiss Arb 24 153 p Tuumlbingen (Inst Geowiss Univ Tuumlbingen)

Kanzock A (1995) Zur Geologie des Hirschberggebietes bei Bre-genz (Vorlandmolasse Quartaumlr) mit lithostratigraphischen Un-tersuchungen in der Oberen Meeresmolasse Diploma thesis Lehrst f Geol TU Muumlnchen 158 p Garching (unpubl)

Keller B (1989) Fazies und Stratigraphie der Oberen Meeresmo-lasse (unteres Miozaumln) zwischen Napf und Bodensee ndash PhD thesis Univ Bern 302 p Bern (unpubl)

Keller B (1990) Wirkung von Wellen und Gezeiten bei der Abla-gerung der Oberen Meeresmolasse ndash Loumlwendenkmal und Glet-schergarten ndash zwei anschauliche geologische Studienobjekte ndash Mitt naturforsch Ges Bern 31 245ndash271 Luzern (Haag [in Komm])

Knipscher HCG (1952) Die Gliederung der ungefalteten Mo-lasse im oumlstlichen Teil Bayerns auf Grund mikropalaumlontolo-gischer Untersuchungen ndash Geol Bavarica 14 48ndash67 Muumln-chen (Bayerisches Geol L-Amt)

Kohler EE amp Haumlussler H (1978) Zur Entstehung von Phospho-rit- und Glaukonitvorkommen der Mittel- und Oberkreide im Helvetikum des Allgaumlus ndash Geol Jb A 46 69ndash91 Stuttgart (Schweizerbart)

Kuhlemann J amp Kempf O (2002) Post-Eocene evolution of the North Alpine Foreland Basin and its response to Alpine tecto-nics ndash Sediment Geol 152 45ndash78 Amsterdam (Elsevier)

Kuntscher H (1986) Houmlhlen Bergwerke Heilquellen in Tirol und Vorarlberg ndash Bildwanderbuch Bd 1 362 p Bergwang (Stei-ger)

Lemcke K (1988) Geologie von Bayern I Das bayerische Alpen-vorland vor der Eiszeit 175 p Stuttgart (Schweizerbart)

Lemcke K von Engelhardt W amp Fuumlchtbauer H (1953) Geolo-gische und sedimentpetrographische Untersuchungen im West-teil der ungefalteten Molasse des suumlddeutschen Alpenvorlandes ndash Geol Jb Beih 11 1ndash182 Hannover (B-Anst Boden-forsch)

Lourens L Hilgen F Shackleton NJ Laskar J amp Wilson D (2004) The Neogene period ndash In Gradstein FM Ogg JG amp Smith AG (eds) A geologic time scale 2004 409ndash440 Cambridge (Cambridge Univ Press)

Miall AD (1992) Alluvial deposits ndash In Walker RG amp James NP (eds) Facies models response to sea-level change 119ndash142 St Johnrsquos (Geol Assoc Canada)

Murray JW (2006) Ecology and applications of benthic foramini-fera 426 p Cambridge (Univ Press)

Naumlgele E (1962) Zur Petrographie und Entstehung des Albsteins ndash N Jb Geol Palaumlont Abh 115 44ndash120 Stuttgart (Schwei-zerbart)

Nemec W (1990) Deltas ndash remarks on terminology and classifica-tion ndash In Colella A amp Prior DB (eds) Corse-grained deltas ndash Spec Publ Int Assoc Sedimentologists10 3ndash12 Oxford (Blackwell)

Odin GS (1988) Glaucony from the gulf of Guinea ndash In Odin GS (ed) Green marine clays ndash Develop Sediment 45 225ndash248 Amsterdam (Elsevier)

Odin GS amp Matter A (1981) De glauconarium origine ndash Sedi-mentology 28 611ndash641 Oxford (Blackwell)

Odin GS amp Pullagar PD (1988) Geological significance of the glaucony facies ndash In Odin GS (ed) Green marine clays ndash Develop Sediment 45 295ndash332 Amsterdam (Elsevier)

Pentildea FAC (2007) The Early Miocene Upper Marine Molasse of the German part of the Molasse Basin ndash a subsurface study Sequence stratigraphy depositional environment and architec-ture 3D basin modelling ndash PhD thesis Eberhard-Karls-Univ Tuumlbingen 119 p Tuumlbingen (unpubl)

Piller WE Harzhauser M amp Mandic O (2007) Miocene Central Paratethys stratigraphy ndash current status and future directions ndash Stratigraphy 4 151ndash168 New York (Micropaleont Press)

Pippegraverr M amp Reichenbacher B (2009) Biostratigraphy and pa-leoecology of benthic foraminifera from the Eggenburgian ldquoOr-tenburger Meeressanderdquo of southeastern Germany (Early Mio-cene Paratethys) ndash N Jb Geol Palaumlont Abh 254 41ndash61 Stuttgart (Schweizerbart)

Pippegraverr M Frieling D amp Reichenbacher B (2007a) Vertiefte Untersuchungen der Schichtenfolge des Eggenburg und Ottnang in der Region 12 ndash Unpubl rep Bavarian Geol Survey 151 p Muumlnchen

Pippegraverr M Reichenbacher B Witt W amp Rocholl A (2007b) The Middle and Upper Ottnangian of the Simssee area (SE Ger-many) micropalaeontology biostratigraphy and chronostrati-graphy ndash N Jb Geol Palaumlont Abh 245 353ndash378 Stuttgart (Schweizerbart)

Ploumlchinger B Oberhauser R amp Woletz G (1958) Das Molasse-profil laumlngs der Bregenzer Ach und des Wirtatobels ndash Jb geol B-Anst 101 293ndash322 Wien (Geol B-Anst)

Postma G (1990) Depositional architecture and facies of river and fan deltas a synthesis ndash In Colella A amp Prior DB (eds) Corse-grained deltas ndash Spec Publ Int Assoc Sedimentolo-gists10 13ndash27 Oxford (Blackwell)

Reichenbacher B (1993) Mikrofaunen Palaumlogeographie und Bio-stratigraphie der miozaumlnen Brack- und Suumlszligwassermolasse in der westlichen Paratethys unter besonderer Beruumlcksichtigung der Fisch-Otolithen ndash Senckenb lethaea 73 277ndash374 Stutt-gart (Schweizerbart)

Reichenbacher B Boumlhme M Heissig K Prieto J amp Kossler A (2004) New approach to assess biostratigraphy palaeoecology and past climate in the South German Molasse Basin during the Early Miocene (Ottnangian Karpatian) ndash Courier Forsch-Inst Senckenberg 249 71ndash89 Stuttgart (Schweizerbart)

Reichenbacher B Kaumllin D amp Jost J (2005) A fourth St Gallen Formation cycle () in the Karpatian Upper Marine Molasse of central Switzerland ndash Facies 51 160ndash172 Berlin (Springer)

Renz HH (1937) Zur Geologie der oumlstlichen St Gallisch-Appen-zellischen Molasse ndash Jb St Gallischen naturwiss Ges 69 (193738) 1ndash128 St Gallen (St Gallische Naturwiss Ges)

Resch W (1977) Bericht 1976 uumlber Profilaufnahmen und mikro-palaumlontologische Untersuchungen in der Oberen Meeresmo-lasse auf Blatt 82 ndash Verh geol B-Anst A 82ndashA 84 Wien (Geol B-Anst)

Roumlgl F amp Steininger F (1983) Vom Zerfall der Tethys zu Mediter-ran und Paratethys ndash Ann naturhist Mus Wien Ser A 85 135ndash163 Wien (Naturhist Mus Wien)

Rutsch RF (1928) Geologie des Belpbergs Beitraumlge zur Kennt-nis der Stratigraphie Palaumlontologie und Tektonik der Molasse



suumldlich von Bern ndash Mitt naturforsch Ges Bern 1927 1ndash194 Bern (Naturforsch Ges Bern)

Schaad W Keller B amp Matter A (1992) Die Obere Meeresmo-lasse (OMM) am Pfaumlnder Beispiel eines Gilbert-Deltakom-plexes ndash Eclogae Geol Helvetiae 85 (1) 145ndash168 Basel (Birkhaumluser)

Schaumlfer A (2005) Klastische Sedimente ndash Fazies und Sequenz-stratigraphie 414 p Muumlnchen (Elsevier)

Schiemenz S (1960) Fazies und Palaumlogeographie der Subalpinen Molasse zwischen Bodensee und Isar ndash Geol Jb Beih 38 119 p Hannover (B-Anst Bodenforsch)

Schlunegger F Matter A Burbank DW amp Klaper EM (1997a) Magnetostratigraphic constraints on relationships between evo-lution of the central Swiss Molasse Basin and Alpine orogenic events ndash Geol Soc America Bull 109 225ndash241 Boulder (Geol Soc America)

Schlunegger F Jordan TE amp Klaper EM (1997b) Controls of erosional denudation in the orogen on foreland basin evolution the Oligocene central Swiss Molasse Basin as an example ndash Tectonics 16 823ndash840 Washington D C (American Geophys Union)

Schmidegg O (1945) Bericht uumlber eine Begehung des Kohlevor-kommens von Birkenberg bei Bregenz ndash Unpubl rep 5 p Wien (Geol B-Anst)

Schmidt AR (1843) Vorarlberg nach den von dem geognostisch-montanistischen Verein veranlaszligten Begehungen dargestellt mit einer Karte und Revisionsbemerkungen von Prof J N Friese 158 p Innsbruck (Wagner)

Schmidt AR (1879) Bergbaue Erz- und Kohlenfunde und beson-ders nutzbare Gesteinsarten in Vorarlberg ndash Oumlsterreichische Z Berg- u Huumlttenwesen 27 376ndash378 Wien

Schmidt C amp Muumlller F (1911) Die Kohlefloumlze in der Molasse bei Bregenz ndash Z prakt Geol 19 (10) 355ndash359 HalleSaale (Knapp)

Scholz H (1986) Beitraumlge zur Sedimentologie und Palaumlontologie der Oberen Suumlszligwassermolasse im Allgaumlu ndash Jb Geol B-Anst 129 (1) 99ndash127 Wien (Geol B-Anst)

Scholz H (1989) Die Obere Meeresmolasse (OMM) am Suumldrand des Molassebeckens im Allgaumlu ndash Geol Bavarica 94 49ndash81 Muumlnchen (Bayerisches Geol L-Amt)

Scholz H (1993) Geologischer Bau und Landschaftsgeschichte des Landkreises Lindau ndash Ber naturwiss Ver Schwaben 79 (Sonderheft) 56 p Augsburg (Naturwiss Ver Schwaben)

Scholz H (1995) Bau und Werden der Allgaumluer Landschaft 290 p Stuttgart (Schweizerbart)

Scholz H (1999) Die bdquoklassischeldquo Molasse-Gliederung vom Suumld-rand des Molassebeckens in Suumldwestbayern ndash bewaumlhrt oder problematisch ndash N Jb Geol Palaumlont Abh 214 (3) 391ndash413 Stuttgart (Schweizerbart)

Scholz H (2000) Die tertiaumlren Grobsedimente am Suumldrande des Molassebeckens im Allgaumlu (Suumldwestbayern) ndash eine Synopsis ndash N Jb Geol Palaumlont Abh 218 (1ndash2) 61ndash84 Stuttgart (Schweizerbart)

Scholz H amp Bienert R (1992) Bausteine und Fossilien aus der Oberen Meeresmolasse bei Kempten ndash Ber naturwiss Ver Schwaben 96 (2) 2ndash12 Augsburg (Naturwiss Ver Schwa-ben)

Scholz H amp Frieling D (2006) Wulstgefuumlge Rutschfalten und Sandsteingaumlnge in Molassesedimenten ndash Hinweise auf seis-mische Unruhe im Oligozaumln und Miozaumln des Alpenvorlandes

ndash N Jb Geol Palaumlont Abh 241 (3) 345ndash382 Stuttgart (Schweizerbart)

Schreiner A (1966) Zur Stratigraphie der Oberen Meeresmolasse zwischen der Oberen Donau und dem Uumlberlinger See (Baden-Wuumlrttemberg) ndash Jber Mitt oberrhein geol Ver N F 48 91ndash104 Stuttgart (Schweizerbart [in Komm])

Sieber R (1959) Palaumlontologisch-stratigraphische Untersu-chungen in der Miozaumlnmolasse Vorarlbergs ndash Verh geol Bun-desanst A 122 ndash A 123 Wien (Geol Bundesanst)

Steininger F Resch W Stojaspal F amp Herrmann P (1982) Bi-ostratigraphische Gliederungsmoumlglichkeiten im Oligozaumln und Miozaumln der Molasse-Zone Vorarlbergs ndash Docum lab geacuteol Lyon H S 7 77ndash85 Lyon (Centre Sci de la Terre Lyon)

Tessier B amp Gigot P (1989) A vertical record of different tidal cyclicities an example from the Miocene Marine Molasse of Digne (Haute Province France) ndash Sedimentology 36 767ndash776 Oxford (Blackwell)

Tucker ME (1985) Einfuumlhrung in die Sedimentpetrologie 265 p Stuttgart (Enke)

Uhlig S (1987) Geroumlllanalytische Untersuchungen im Pfaumlnderge-biet ndash Diploma thesis Lehrstuhl fuumlr Geologie TU Muumlnchen 36 p Muumlnchen (unpubl)

Weber L amp Weiss A (1983) Bergbaugeschichte und Geologie der oumlsterreichischen Braunkohlenvorkommen ndash Arch Lagerst-Forsch Geol B-Anst 4 1ndash317 Wien (Geol B-Anst)

Weiss A (1984) Zur Geschichte des Braunkohlevorkommens im Wirtatobel ndash Berg- amp huumlttenmaumlnn Mh 129 (12) 471ndash475 Wien (Springer)

Wenger WF (1987a) Die Foraminiferen des Miozaumlns der baye-rischen Molasse und ihre stratigraphische sowie palaumlogeogra-phische Auswertung ndash Zitteliana 16 173ndash340 Muumlnchen (Bayerische Staatsslg Palaumlont Geol)

Wenger WF (1987b) Die Basis der Oberen Meeresmolasse im westlichen Oberbayern am Uumlberlinger See in Vorarlberg und St Gallen ndash Mitt bayerische Staatsslg Palaumlont hist Geol 27 159ndash174 Muumlnchen (Bayerische Staatsslg Palaumlont hist Geol)

Wenz W (1933) Zur Land- und Suumlszligwassermolluskenfauna der subalpinen Molasse des Pfaumlndergebietes ndash Senckenbergiana 15 7ndash12 Frankfurt a M (Senckenb Naturforsch Ges)

Wenz W (1935) Weitere Beitraumlge zur Land- und Suumlszligwasser-Mol-luskenfauna der subalpinen Molasse des Pfaumlndergebiets ndash Sen-ckenbergiana 17 (5ndash6) 223ndash225 Frankfurt a M (Senckenb Naturforsch Ges)

Wright VP amp Tucker ME (1991) Calcretes an introduction ndash In Wright VP amp Tucker ME (eds) Calcretes ndash Int Assoc Sedimentologists Reprint Ser 2 1ndash22 Oxford (Blackwell)

Zoumlbelein HK (1985) Helicidenschichten und Albstein in der mio-zaumlnen Vorlandmolasse Suumldwestdeutschlands ndash Jh geol L-Amt Baden-Wuumlrttemberg 27 41ndash92 Freiburg i Br (Geol L-Amt Baden-Wuumlrttemberg)

Zweigel J (1998) Eustatic versus tectonic control on foreland ba-sin fill ndash sequence stratigraphy subsidence analysis stratigra-phic modelling and reservoir modelling applied to the German Molasse basin ndash Contrib Sediment Geol 20 1ndash140 Stuttgart (Schweizerbart)

Manuscript received 09072009Accepted for publication 26082009



1 Introduction

Since more than 100 years the Pfaumlnder area has received considerable attention initially because of the presence of economically important lignite coal seams and fossiliferous horizons The Pfaumlnder sediments belong to a mainly marine succession ndash the Upper Marine Molasse ndash and developed in front of a large alluvial fan as part of a deltaic complex of which the most proximal part (talus centre) is the well-known Wirtatobel section (Schaad et al 1992)

The geographic location of the Pfaumlnder (Fig 1) should be ideal for a correlation of the Upper Marine Molasse between Switzerland and Southwest Germany which still bears con-siderable uncertainties (cf Reichenbacher et al 2005) How-ever due to the mostly deltaic environment of the Pfaumlnder sediments such a correlation had not been attempted up to date In this study we focus on the so far not investigated distal part of the Pfaumlnder delta to the Northeast of the talus centre We investigated the lithofacies lithostratigraphy and sedimentary environment at four well exposed sections and performed a sequence stratigraphical analysis We also at-tempted bio- and magnetostratigraphical techniques which however failed because of the special sedimentary condi-tions as the sedimentation rate was high and fi ne-grained clastic layers were scarce or even lacking Our data show that lithostratigraphic correlation is possible between the proximal and distal portions of the Pfaumlnder delta Further-more we suggest a new correlation scheme for the Upper Marine Molasse in southwestern Germany and eastern Swit-zerland

2 Study area

21 Geography

The Pfaumlnder ridge (height 1064 m) rises above Bregenz at the eastern margin of Lake Constance in the southwestern corner of the South German part of the Molasse Basin (Fig 1C) Its northern slopes gradually pass into the North Alpine Foreland whereas the steeper southern slopes expose the Early Miocene sediments of the Upper Marine Molasse in deeply incised gorges (ldquoTobelrdquo in the local dialect) The deepest of these gorges are the Wirtatobel directly beneath the summit of the Pfaumlnder Mountain and the Kesselbach southeast of the summit marking the AustrianGerman state border (Fig 1D) Only the Upper Marine Molasse succes-sion of the Wirtatobel has been studied before (eg Blumrich 1930 Ploumlchinger et al 1958 Herrmann amp Schwerd 1983 Schaad et al 1992)

22 Geology

221 Overview

The Molasse Basin is bordered by the Alpine nappes to the South the Variscan crystalline basement rocks of the Bohe-

mian Massive to the Northeast and the Mesozoic strata of the Alb and Swiss Jura mountains to the North and North-west (Fig 1C) During the Oligocene and the Miocene clas-tic sediments accumulated in the basin under terrestrial and marine conditions They mostly contain debris derived from the quickly growing Alps to the South (eg Lemcke 1988 Scholz 2000)

Repeatedly the basin was invaded by the sea (eg Allen et al 1985 Tessier amp Gigot 1989 Kuhlemann amp Kempf 2002) and became part of the western Paratethys In the Early Miocene (Eggenburgian) a seaway intermittently extended from the Caspian Sea via the Molasse Basin to the Rhocircne Valley and the Tethys the today Mediterranean Sea (Roumlgl amp Steininger 1983 Bieg et al 2008) During this time alluvial fans and delta complexes supplied by Alpine debris from the South prograded northward towards shallow marine envi-ronments fi lling the Molasse Basin In the late Early Miocene (Ottnangian) the fi nal period of marine sedimentation was succeeded by the deposition of the Upper Brackishwater Molasse and the Upper Freshwater Molasse (Lemcke 1988 Reichenbacher 1993)

The present study focuses on the sediments of the Upper Marine Molasse which were deposited during the Early Miocene in the Eggenburgian and Ottnangian (approxi-mately 20ndash17 Ma ago Wenger 1987a Berger et al 2005) The stratigraphy of these sediments is based on benthic fo-raminifera from the Southeast German and Austrian part of the basin (Hagn 1959 1961 Knipscher 1952 Wenger 1987a b Pippegraverr et al 2007a b Pippegraverr amp Reichenbacher 2009) However in the proximal coastal areas foraminifera are scarce andor poorly preserved (see Wenger 1987b and this study) due to high sedimentation rates and coarse grain sizes In the central and West German part of the Molasse Basin at least two transgressive-regressive cycles were recognised in the Upper Marine Molasse on the basis of differences in the lithofacies (Lemcke et al 1953 Schreiner 1966 Gall 1975

Fig 1 Simplifi ed maps of (A) Germany (frame indicating position of C) and (B) of the Molasse Basin (frame indicating position of C) (C) German part of the Molasse Basin (white colour) with study area (frame) areas with outcropping Upper Marine Molasse are shown in grey colour Cliffl ine sensu Lemcke (1988) Map source Geological map of the South German Molasse 1 300 000 Abele et al (1955) (D) Geological map of the Pfaumlnder area (simplifi ed) with the studied sections modifi ed after Scholz (1993) W = Wirtatobel section L = Leckenbach section H = Huberbach section K = Kes-selbach section R = Rothenbach section

Abb 1 Stark vereinfachte Kartendarstellung von (A) Deutschland (der Rahmen zeigt die Lage von C) und (B) des Molassebeckens (der Rahmen zeigt die Lage von C) (C) Der deutsche Anteil des Molassebeckens (weiszlig) mit dem Untersuchungsgebiet (Rahmen) die Gebiete mit uumlber Tage ausstreichender Oberer Meeresmolasse sind grau dargestellt Die Kliffl inie ist im Sinne von Lemcke (1988) dargestellt Kartengrundlage Geologische Uumlbersichtskarte der Suumlddeutschen Molasse 1 300 000 Abele et al (1955) (D) Geolo-gische Karte des Pfaumlnder-Gebietes (vereinfacht) mit den bearbeite-ten Profi len veraumlndert nach Scholz (1993) W = Wirtatobel L = Leckenbach H = Huberbach K = Kesselbach R = Rothenbach




















4 Results

41 Facies types













































































































51 Previous studies








52 This study











ad




























61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References












































































































































4 Results

41 Facies types













































































































51 Previous studies








52 This study











ad




























61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References
























































































































































































































51 Previous studies








52 This study











ad




























61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References





























































































































52 This study











ad




























61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References































































































































ad




























61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References

































































































































61 Sequence 1















62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References

































































































































62 Sequence 2





















7 Conclusion













8 Acknowledgements


9 References










































































































































7 Conclusion













8 Acknowledgements


9 References

































































































































8 Acknowledgements


9 References


























































































































sequence stratigraphy of an alluvial fan-delta in the upper marine molasse (pfänder area, late...

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