p2 geologi struktur tektonik lempeng

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Geologi Struktur(Tektonik Lempeng)

Oleh :Irvani

Universitas Bangka Belitung Jurusan Teknik Pertambangan

Referensi :• Van Der Pluijm, B. A. and Marshak, S. 2004. Earth Structure. 2nd Edition. W. W.

Norton & Company, Inc., USA.• Rowland, S.M., Duebendorfer, E.M. and Schiefelbein, I.M. 2007. Structural Analysis

and Synthesis : A Laboratory Course in Structural Geology. 3th Edition. Blacwell Publishing Ltd. Voctoria, Australia.

• Bates, R.L. and Jackson, J.A., 1987. Glossary Geology. 3th Edition. American Geological Institute Elexandria, Virginia.

• Davis, G.H. 1984. Structural Geology of Rocks and Regions. John Wiley & Sons, New York.

• Ragan, D.M. 2009. Structural Geology : An Introduction to Geometrical Techniques. 4th Edition. Cambridge University Press, New York.

• Twiss R.J. And Moores, E.M. 2007. Structural Geology. 2nd Edition. W.H. Freeman and Company, USA.

• Ramsey J. and Huber, M. 1983. The Techniques of Modern Structural Geology : Strain Analysis. Vol. 1. Academic Press, Inc., London.

• Ramsey J. and Huber, M. 1987. The Techniques of Modern Structural Geology : Fold and Fractures. Vol. 2. Academic Press, Inc., London.

• Ramsey J. and Huber, M. 2000. The Techniques of Modern Structural Geology : Applications of Continuum Mechanics in Structural Geology. Vol. 3. Elsevier Academic Press, Inc., California.

• Cox, A. and Hart, R.B. 1986. Plate Tectonics : How It Works. Blacwell Scienific Publications, Inc., California.

• Trouw, R.A.J. and Passchier, C.W. 1996. Microtectonics. Springer – Verlag Berlin Heidelberg, Germany.

• DLL.


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Pokok Bahasan :I Pendahuluan (P.1)

II Tektonika & Orogenesa (P.2-3)a. Tektonik lempengb. Orogenesa

III Gaya, Tegasan, Strain & Deformasi (P.4-5)

a. Gaya & Tegasanb. Strain & Deformasi

IV Struktur Geologi (P.6-9)a. Unsur strukturb. Lipatan c. Kekar d. Sesar

V Identifikasi Struk. Geologi (P.10-11)a. Pengukuran dan analisis

struktur geologi b. Analisis geofisika struktur

geologi

VI Aplikasi Struk. Geologi (P.12-13)a. Mineralisasi b. Migasc. Kebencanaan geologi

VII Geologi Struk. Indonesia (P.14)a. Umumb. Sumatra&Jawa c. Bangka Belitung


DefinisiTektonika ???- TECTONICS: Involving force in formation of

structural geology- SRUCTURAL GEOLOGY: the branch of geology

that deals with the form, arrangement, and internal structure of the rocks, and especially with description, representation, and analysis of structures, chiefly on moderate to small scale. The subject is similar to tectonics, but the latter is generally used for the broader regional or historical phases (Bates & Jackson, 1987).


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Big Bang dan Teori Nebula (Geologi modern)Pembentukan Bumi & Semesta

Scenario begins about 13.7 billion years ago with the Big Bang. The debris from this explosion (almost hydrogen and helium), began to cool and condense into the first stars and galaxies.


Lutgens, Tarbuck and Tasa (2012)

Chemical Subdivision of Earth

• Crust• Mantle• Core

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Subsystems of Earth :The atmosphere,hydrosphere,biosphere, lithosphere, mantle, and core.

Monroe & Wicander (2009)

Struktur BumiUniversitas Bangka Belitung Jurusan Teknik Pertambangan

Interactions Among Earth’s Principal Subsystems

Monroe & Wicander (2009)

.....Struktur Bumi


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Struktur Tubuh BumiEarth’s interior is divided into three different layers based on compositional differences—the crust, mantle, and core.



Schmince (2004)


....Struktur Tubuh Bumi

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.....Struktur Tubuh Bumi

Earth’s interior based on physical properties—the lithosphere, asthenosphere, lower mantle, outer core, and inner core.



The rigid lithosphere includes the crust and uppermost mantle; it forms the plates. The ductile asthenosphere acts as a lubricating layer beneath the lithosphere. Oceanic lithosphere averages 70 kilometers thick; continental lithosphere varies from 125 to 250 kilometers thick.

Carlson et al. (2011)

.....Struktur Tubuh Bumi


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Estimated (A) temperature and (B) pressure with depth into Earth


..... Struktur Tubuh Bumi


The P-wave shadow zone, caused by refraction of P waves within the Earth’s core.

The S-wave shadow zone. Because no S waves pass through the core, the core is apparently a liquid (or acts like a liquid).


Geofisika Struktur Bumi


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The velocity of seismic P and S waves generally increases with depth except in the low-velocity zone. The plastic asthenosphere slows down seismic waves. Velocity increases at 400 and 670 kilometers may be caused by mineral collapse.


....... Geofisika Struktur Bumi


Characteristics of Oceanic Crust and Continental Crust


.....Geofisika Struktur Bumi


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slopeshelf Continental crust (SIAL)

ocean ocean

Oceanic crust (SIMA)

Struktur Kulit BumiEarth’s Crust

Durant (?) - Slide


Orogenic belt (mountains): deformed,folded and faulted,rocks

Platform: mostly flat (undeformed)Phanerozoic rocks (0-540 ma)

Orogenic belt

shield+ platform= craton

Shield: Oldest(Precambrian)rocks exposed

........ Struktur Kulit BumiIdealized cross section of a continent

Durant (?) - Slide


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Profiles of seafloor topography

The vertical scales differ from the horizontal scales, causing vertical exaggeration, which makes slopes appear steeper than they really are.


.......Struktur Kulit Bumi


(A) Vertical exaggeration 25 times. The continental slope has an actual slope of only 4 or 5 degrees, but the great vertical exaggerationof this drawing about 60°.

Continental shelf and continental slope

The continental shelf lies upon continental crust, and the continental rise lies upon oceaniccrust.


.......Struktur Kulit Bumi


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Alfred Wegener (German meteorologist, 1910 – 1930) published his theory of continental drift. - Observations were supported by geographic fit, fossil evidence, and geologic patterns across the Atlantic.- The continents were composed of lighter, less dense materials (sial - silicon and aluminum). The continents drifted across the denser material of the Earth’s mantle and the ocean floor (sima - silicon and magnesium).- The driving forces behind continental drift were derived from known forces such as the rotation of the Earth, precession (a small conical rotation) of the Earth’s axis, or tidal friction.

Frisch et all. (2011)


Continental Drift Concept (Old Idea)

Reconstruction of the supercontinent Pangaea (AfterWegener, 1915). The diverse geological and climatologicaldata from different continentsfit like a jig-saw puzzleon this reconstruction.Panthalassa was the giantocean that stood oppositeto Pangaea.



...... Continental Drift

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Pangaea breakup and continental drift

Carlson et all. (2009)


Distribution of plant and animal fossils that are found on the continents of South America, Africa, Antarctica, India, and Australia give evidence for the southern supercontinent ofGondwana. Carlson et all. (2009)


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The Plate Tectonic Concept“Both continental and oceanic crust, move on top of ductile mantle.”

The lithosphere (Greek shell of rock) ranges in thickness from 70 to 150 km or more, thicker below the continents, thinner below the oceans.

The asthenosphere behaves in ductile fashion andlocally contains pockets of molten rock.



- Plate tectonics remains the first and only global geodynamic theory which orchestrates all known tectonicphenomena including earthquake zones, mountainbuilding, structural patterns, nature of sedimentary basins, magmatism, and metamorphism – plate tectonics is an elegant and comprehensive synthesis of Earth’sgeodynamics.- The theory of plate tectonics is that it is based on the tectonics of present Planet Earth (e. g., Hess, 1962; Vine and Matthews, 1963; Wilson, 1965; Isacks et al., 1968; LePichon, 1968; Morgan, 1968; McKenzie and Morgan, 1969; Dewey and Bird, 1970).



..... Plate Tectonic

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The major plates of the world.

Carlson et all. (2009)



Nearly all of the presently existing plates contain areas with both continental and oceanic crust.


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The present plate configurations and plate motions on Earth;



Three types of plate boundaries: convergent, divergent, and transform.


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Block diagramsshowing the three types of plate boundaries.



Block diagrams of the outer shells of the Earth(Plate boundaries : passive continental margins)



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......Passive Continental Margin

A contour current flowing along the continental margin shapes the continental rise by depositing fine sediment. Coarse layers within the continental rise were deposited by turbidity currents flowing down the continental slope.Carlson et al. (2011)


Block diagrams of the outer shells of the Earth(Plate boundaries : active continental margins)



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......Active continental margin



mid-oceanic ridge (MOR)

(A) Hydrothermal circulation of seawater at ridge crest creates hot springs andmetallic deposits in rift valley.

(B) “Black smoker” or submarine hot spring on the crest of the mid-oceanic ridge in the Pacific Ocean



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fast-spreading: magma enters a large magma chamber in crust;broad bulge exists at ridgeslow-spreading: magma chamber freezes between pulses ofspreading; axial rift valley occurs

from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270

....... mid-oceanic ridge


(A) Seamounts are conical mountains on the sea floor,

(C) The present depth of a guyot is due to subsidence.

(B) The flat summit of a guyot was probably eroded by waves when the top of a seamount was above sea level.


Seamounts


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Goldfinger, Koppers, Winter (2010) : Plate Tectonics-Slide

Mekanisme Pergerakan Lempeng



..... Mekanisme Pergerakan Lempeng


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