geotektonik - divergent

7/26/2019 Geotektonik - Divergent

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DIVERGENT TECTONICS



DIVERGENT TECTONICS

LITHOSPHERIC

PLATES

STYLE OF

RELATIVEPLATE MOVEMENT

AND PLATE

INTERACTIONS

DIVERGENT

MAGMATIC

ACTIVITY

STRUCTURAL

STYLE

BASIN

FORMATION

ANDEVOLUTION

ASSOCIATED

TECTONISM



DIVERGENT TECTONICS

DIVERGENT

MAGMATIC

ACTIVITY

STRUCTURAL

STYLE

BASIN

FORMATION

ANDEVOLUTION

EXTENSIONAL

TECTONIC REGIME

RESULTED IN



DIVERGENT TECTONICS

DIVERGENT TECTONIC AND

EXTENSIONAL TECTONIC REGIMES

TECTONIC REGIME DEFINITION :

REGION INFLUENCED BY CERTAIN

TECTONIC ACTIVITY

RESULTED IN BULK PROPERTIES

DEPICTING THE BEHAVIOR

OF CERTAIN TECTONIC PROCESSES

STRUCTURAL PATTERN, ROCK ASSOCIATION

RESULTED FROM SEDIMENTATION -

METAMORPHISM AND MAGMATISM



DIVERGENT TECTONICS

EXTENSIONAL

TECTONIC

REGIME

MAIN SOURCE

OF STRESS

- OCEAN RIDGES

- CONTINENTAL

MARGINS- PLATEAU

UPLIFTS

• FORCES PRODUCED

FROM SUBDUCTION

• DENSITY IMBALANCES



DIVERGENT TECTONICS

EXTENSIONAL TECTONIC REGIME

AREASSOCIATED WITH

DIVERGENT PLATEINTERACTION

CONVERGENT PLATEINTERACTION

OCCURING AT

PLATE MARGINS

( PLATEBOUNDARY)

INTRA PLATE

AS WELLAS


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EXTENSIONAL TECTONIC REGIME

ASSOCIATED WITH

CONVERGENT PLATE

INTERACTION

COMMONLY FOUND AT

PLATE MARGINS

( PLATEBOUNDARY)

INTRA PLATE

FRONT AND

INTRA MAGMATIC ARC

BEHIND

MAGMATIC ARC

OCCUPIES



PLATE TECTONIC SETTING OF EXTENSIONAL SYSTEM

BACK-ARC

RIFTINGCONTINENTAL

AND OCEANIC

RIFTING



A) Domino

B) Listric

C) ImbricateD) Listric and Planar

Hill, 2003


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1. OCEAN RIDGES

2. CONTINENTAL RIFTS

OF TYPE - I

3. CONTINENTAL EXENSIONALAT CONVERGENT BOUNDARY;

BACK-ARC EXTENSIONAL

4. STRIKE-SLIP EXTENSIONAL


OF TYPE-II

2. INTRAPLATE EXTENSIONAL

BASINS

PLATE BOUNDARY

REGIMES

INTRAPLATE

REGIMES



DIVERGENT TECTONICS

1. OCEAN RIDGES





PLATE BOUNDARY

REGIMES



MOR CH R CTERISTICS

DIVERGENT TECTONICS

1. TOPOGRAPHY (≈1000 km) broad ridges with narrowcentral rifts.

2. BASALT VOLCANISITY mostly tholeitic composition

3. HIGH HEAT-FLOW

4. NEGATIVE GRAVITY ANOMALIES (melts)

5. SEISMIC ACTIVITY (mainly shallow earthquakes)

6. MAGNETIC ANOMALIES oriented parallel with the

ridges



DIVERGENT TECTONICS

1. OCEAN RIDGES





PLATE BOUNDARY

REGIMES



DIVERGENT TECTONICS

1. OCEAN RIDGES


OF TYPE - I

3. CONTINENTAL EXENSIONAL

AT CONVERGENT BOUNDARY;BACK-ARC EXTENSIONAL

4. STRIKE-SLIP EXTENSIONAL • DIP SLIP DISPLACEMENT

CHARACTERIZED THE

FLANKING FAULT SCARPS

• MAKES UP 32.7 % OF THE

SURFACE AREA

• HIGH HEAT FLOW ALONG

THE RIDGE AXIS

• THE PRESENCE OF

ASTHENOSPHERIC MANTLECLOSE TO THE SURFACE



DIVERGENT TECTONICS



DIVERGENT TECTONICS

1. OCEAN RIDGES


3. CONTINENTAL EXENSIONAL

AT CONVERGENT BOUNDARY;BACK-ARC EXTENSIONAL

4. STRIKE-SLIP EXTENSIONAL• DIP SLIP DISPLACEMENT

CHARACTERIZED THE

FLANKING FAULT SCARPS

INDICATE EXTENSIONNORMAL TO RIFT AXIS

DIFFERENCE IN

SPREADING RATE

ACCOMMODATE BY SHORT

TRANSFORM FAULTS



DIVERGENT TECTONICS

EXTENSIONAL

AT CONVERGENT



DIVERGENT TECTONICS

BACK-ARC BASIN AS EXTENSIONAL AT CONVERGENT



DIVERGENT TECTONICS



DIVERGENT TECTONICS


OF TYPE - I

• CLASSIFICATION

• ORIGIN

• ACTIVE RIFT

-CONSTRUCTIVE

PLATE BOUNDARY

- INTRA PLATE

• INACTIVE RIFT -FAILED ARMS;

( AULACOGEN )

• MANTLE ACTIVATED

• LITHOSPHERE ACTIVATED

(CONDIE, 1982)



DIVERGENT TECTONICS

• ACTIVE RIFT

-CONSTRUCTIVE

PLATE BOUNDARY

- INTRA PLATE

EAST AFRICAN -

RED SEA – GULF OF ADEN

RIFT

LINKS WITH INDIAN OCEAN

MODERN ANALOUGE

WITH RIFT SYSTEM

WHICH RESULTEDIN THE BREAK UP

OF PANGEA

FLOORED BY OCEANICCRUST;

COMMENCED OPENING

LATE MIOCENE

DIVERGENCE RATE

2 CM/Y



DIVERGENT TECTONICS

• ACTIVE RIFT

-CONSTRUCTIVE

PLATE BOUNDARY

- INTRA PLATE

RHINE GRABEN (RIFT)

DUE TO ALPINE

OROGENY

• COMMENCE IN L.CRETAC.

• EOC.-OLIG0. RIFTING AND SUBSID.

• MIO.-PLIO. EXTENSION DECREASED

• M.PLIO. REACTIVATION TO SINISTRAL SH.



INTRACONTINENTAL EXTENSION

1. BRITTLE-DUCTILE TRANSITION AND

SUB-HORIZONTAL DECOUPLING

2. CRUSTAL-PENETRATING LOW-ANGLE

NORMAL FAULT

3. HYBRID MODEL



DIVERGENT TECTONICS


OF TYPE - I

• ORIGIN



(CONDIE, 1982)



DIVERGENT TECTONICS


OF TYPE - I


(BURKE AND DEWEY, 1973)

RIFT

CRUST

LITHOSPHERE

ASTHENOSPHERE

# DOMAL UPLIFTCAUSE OF

RIFTING

MANTLE PLUME(“DIAPIR”)

# ABUNDANT VULCANICITY



DIVERGENT TECTONICS


OF TYPE - I

• ORIGIN



(CONDIE, 1982)



DIVERGENT TECTONICS



(CONDIE, 1982)

CRUST

LITHOSPHERE

ASTHENOSPHERE

RIFT

# EXTENSIONAL

STRESS MAXIMUM

DURING BREAK-UP

OF CONTINENT

COMMENCE WITH

GRABEN AND BASIN

# VULCANISM AT LATER STAGE



DIVERGENT TECTONICS




CRUST

LITHOSPHERE

THE EAST AFRICAN RIFT

SYSTEM;

RIFT

CONNECTED VIA AFAR

TRIPLE JUNCTION WITH

THE RED SEA – GULF OF

ADEN



DIVERGENT TECTONICS



THE EAST AFRICAN RIFT

SYSTEM;

CONNECTED VIA AFAR

TRIPLE JUNCTION WITH

THE RED SEA – GULF OF

ADEN

TO THE WEST LINK WITH

THE ATLANTIC

# ASSOCIATED 3 DOMAL UPLIFT

AS CENTRES OF ALKALINE

VULCANICITY

ACROSS

CENTRAL AFRIKA

TO 2 DOMAL UPLIFT

DARFUR AND ADAMAOUA

BY MEANS OF 2 RIFTS :

• ABU GABRA AND

• NGAONDERE



DIVERGENT TECTONICS

EAST AFRICAN

RIFT SYSTEM



DIVERGENT TECTONICS



DIVERGENT TECTONICS

“DIVERGENT

TECTONIC REGIME”

TERJADI DI WILAYAH

PUNGGUNG

TENGAN SAMUDRA



DIVERGENT TECTONICS

TIPE

PASIVE CONTINENTAL

MARGIN BASIN



DIVERGENT TECTONICS

PERKEMBANGAN LENGKAP DARI

DIVERGENT CONTINENTAL MARGIN



EXTENSIONAL FAULT STYLES

A. CRUSTAL EXTENSIONAL FAULT SYSTEMS

1. Intracontinental Rift Systems – Dominantly Planar Arrays

2. Passive Continental Margins – Dominantly Planar Arrays

3. Mid-Ocean Ridge Systems – Planar

4. Back-Arc Basins – Planar

5. Extensional Collapse Basins – Low-angle Planar and Listric6. Strike-Slip Pull-Apart Basins – Dominantly Planar

B. DETACH EXTENSIONAL FAULT SYSTEM

1. Propagrational Delta Systems – Listric Arrays

2. Passive Continental Margins – Dominantly Listric

3. Salt Detachment and Diapirs – Dominantly Listric

4. Submarine Scrap Collapses – Listric

After McClay (1996)

RIFT BASIN NOMENCLATURES



RIFT BASIN NOMENCLATURES

•

TECTONO-STRATIGRAPHY



SELESAI

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