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Geologi Struktur (Strain & Defor Deformasi) masi)
Oleh : Irvani
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Referensi : • • • • • • • • • • • •
Van Der Plui Pluijm, jm, B. B. A. and and Marsha Marshak, k, S. S. 2004. 2004. Earth Structure. Structure. 2nd Edition. Edition. W. W . Norton & Company, Inc., USA. Rowland, Rowla nd, S.M., Dueben Duebendorfe dorfer, r, E.M. and Schie Schiefelbein felbein,, I.M. 2007. Structural Analysis and Synthesis : A Laboratory Course in Str uctural Geology. Geology . 3th Edition. Blacwell Publishing Ltd. Voctoria, Australia. Bate Ba tes, s, R.L. R.L. and and Jackso Jackson, n, J.A. J.A.,, 1987 1987.. Glossary Geology. Geology. 3th Edition. American Geological Institute Elexandria, Virginia. Dav Da vis is,, G. G.H. 19 1984 84.. Structural Geology of Rocks and Regions. Regions . John Wiley & Sons, New York. Raga Ra gan n, D.M D.M.. 20 2009 09.. Structural Geology : An Introduction to Geometrical Techniques. Techniques . 4th Edition. Cambridge University Press, N ew York. Twis Tw iss s R.J. R.J. And And Moo Moores res,, E.M. E.M. 200 2007. 7. Structural Geology. Geology. 2nd Edition. W .H. Freeman and Company, USA. Ramse Ra msey y J. an and d Hube Huber, r, M. M. 1983 1983.. The Techniques of Modern Structural Geology : Strain Analysis. Analysis. Vol. 1. Academic Press, Inc., London. Ramse Ra msey y J. an and d Hube Huber, r, M. M. 1987 1987.. The Techniques of Modern Structural Geology : Fold and Fractures. Fractures . Vol. 2. Academic Press, Inc., London. Ramse Ra msey y J. an and d Hube Huber, r, M. M. 2000 2000.. The Techniques of Modern Structural Geology : Applications of Continuum Mechanics in Structural Geology. Geology. Vol. 3. Elsevier Academic Press, Inc., California. Cox, Co x, A. and and Ha Hart, rt, R.B R.B.. 1986 1986.. Plate Tectonics : How It Works. Works . Blacwell Scienific Publications, Inc., California. Trouw, Tro uw, R.A R.A.J. .J. and Pass Passchie chier, r, C.W. C.W. 1996 1996.. Microtectonics Microtectonics.. Springer Springer – Verlag Berlin Berlin Heidelberg, Germany. DLL.
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Pokok Pok ok Ba Bahas hasan an : V Identi Identifikasi fikasi Struk. Struk. Geologi (P.10-11) a. Peng Pengukur ukuran an dan analisis analisis struktur struk tur geolo geologi gi II Tektonika Tektonika & Orogenesa Orogenesa (P.2-3) b. Analisis geofisika struktur a. Tektonik lempeng geologi b. Orogenesa I Pendahuluan (P.1)
IIII Gaya II Gaya,, Tegangan, Tegangan, Strain & Deformasi (P.4 (P.4-5) -5) a. Gaya Gaya & Tegan Tegangan gan b. Strain & De Deformasi formasi
VI A Aplika plikasi si Struk Struk.. Geol Geologi ogi (P.12 (P.12-13) -13) a. Mineralisasi b. Migas c. Keb Kebencan encanaan aan geologi geologi
IV Strukt Struktur ur Geologi Geologi (P.6-9) (P.6-9) a. Unsur struktur b. Lipatan c. Kekar d. Sesar
VII Geologi Struk Struk.. Indo Indonesi nesia a (P.1 (P.14) 4) a. Umum b. Sumatra&Jawa c. Bangka Belitung
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I. STRAIN Strain describes the changes of points in a body relative to each other; it describes the distortion of a body.
Pluijm & Marshak (2004)
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HOMOGENEOUS STRAIN STRAIN ELLIPSOID
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AND
THE
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COAXIAL AND NON-COAXIAL STRAIN ACCUMULATION
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THE MOHR CIRCLE FOR STRAIN
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STRAIN STATES
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Elastic Behavior
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Confining Pressure
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Temperature
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Pore-Fluid Pressure
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II. DEFORMASI Deformation describes the collective displacements of points in a body; in other words, it describes the complete transformation from the initial to the final geometry of a body. Deformation is described by: 1. Translation 2. Rotation 3. Distortion 4. Dilation Pluijm & Marshak (2004)
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Brittle Deformation The permanent change that occurs in a solid material due to the growth of fractures and/ or due to sliding on fractures. Brittle deformation only occurs when stresses exceed a critical value, and thus only after a rock has already undergone some elastic and/or plastic behavior.
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Rocks that respond brittlely to stress break. Where a rock breaks and no movement takes place is called a fracture or joint.
Fractures in the shallow crust are commonly evidenced by quartz veins, where fluid once flowed and later crystallized.
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Ex : Faults A fracture along which movement takes place is a fault.
acute angle = hanging wall
obtuse angle = foot wall
e l a n p l t u f a
We classify faults based on direction of movement of individual blocks, with reference to a horizontal plane.
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Ductile Deformation A general term for the response of a solid material to stress such that the rock appears to flow mesoscopically like a viscous fluid. In a material that has deformed ductilely, strain is distributed, i.e., strain develops without the formation of mesoscopic discontinuities in the material. Ductile behavior can involve brittle (cataclastic flow) or plastic deformation mechanisms.
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Ductile and Brittle Deformation Features
Ductile
Brittle
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Composite Brittle + Ductile Features Many deformation structures are composite in nature. Fold belts (compressional) commonly contain numerous reverse faults.
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Brittle + Ductile Features (small scale) A vein such as this may have formed in a fracture, but subsequent ductile deformation caused its wiggl y appearance.
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Terima Kasih
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