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Geologic Structures. Structural Geology – study of deformation of rocks and the forces that cause deformation. Structural Geology is concerned with deformation of the Earth's crust. Where is deformation occurring today? Plate boundaries Active orogenic belts (Impact structures)
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Geologic Structures Structural Geology – study of deformation of rocks and the forces that cause deformation
Structural Geology is concerned with deformation of the Earth's crust Where is deformation occurring today? • Plate boundaries • Active orogenic belts • (Impact structures) Where has deformation occurred in the past? • Identify ancient orogens • Relative ages of rocks vs. deformation Why do we want to understand deformation? • Natural hazards • Economic resources • Basic science
Geologic Structures Stress – Compression, Tension, Shear
Stress – Strain relations Strain – Elastic, Plastic, Brittle Elastic range
Geologic Maps Geologic Maps – strike & dip (angle, direction), geologic cross-sections http://www.visualentities.com/applets/blockdiagram.htm
Geologic Maps Folds – antiforms, synforms, limbs, hinge line (axis), axial plane, domes, basins,
Folds Domes
Folds Plunging folds, domes, basins
Types of folds Open, isoclinal, overturned, recumbent
Joints, cracks, fractures Tensional, compressional, sets
Joints, cracks, fractures Several sets
“Anticracks” – pressure solution Stylolites
Faults Fault plane, hanging wall, footwall Faults – dip-slip, strike-slip, oblique-slip
Fault planes Dip-slip – normal, reverse
Dip-slip – normal fault zone, Iran Pliocene-Pleistocene, Zanjan-Tabriz highway
התקצרות – חיובית התארכות - שלילית כיווני מאמץ והעתקים
התקצרות – חיובית התארכות - שלילית כיווני מאמץ ראשיים והעתקים
Geologic Structures Mining
Geologic Structures Oil Reservoirs