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Lecture 7 Reverse faults and folds I. Environments. Orthogonal convergence Himalaya Zagros Caucasus. Zagros, Elborz, etc. Caucasus. Himalaya. Earthquakes 1962-2003. Eurasian plate. African plate. Arabian plate. Indian plate. Greater Caucasus. Elborz. Lesser Caucasus. Kopet Dagh.
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Environments • Orthogonal convergence • Himalaya • Zagros • Caucasus
Zagros, Elborz, etc Caucasus Himalaya
Eurasian plate African plate Arabian plate Indian plate
Greater Caucasus Elborz Lesser Caucasus Kopet Dagh Zagros Himalaya
Tehran J. Hollingsworth & M.J. Bolourchi
North Tehran Fault Tehran J. Hollingsworth & M.J. Bolourchi
Zagros, Elborz, etc Caucasus Himalaya
High-Himalaya Tibet Lesser-Himalaya Sub-Himalaya Gangetic plain Topographic profile and simplified geological cross section across the Himalaya of central Nepal. (Lave and Avouac, 2000)
A deep structure constrained from structural geology, seismic profiles, gravity and MT sounding. all thrust faults seem to sole at depth into the MHT (Avouac, 2003)
Determining active fold growth from abandoned river terraces (Lave and Avouac, 2000)
Holocene slip rate on MFT : 21 +/- 1.5 mm/yr (Lave and Avouac, 2000)
21 +/-1.5 mm/yr Over the long-term, shortening across the Central Nepal Himalaya is absorbed by 21 +/- 1.5 mm/yr of thrusting along a single fault the MFT-MHT (Cattin and Avouac, 2000)
The pattern of uplift derived from incision rates, is consistent with thrusting over a mid-crustal ramp at front of the higher Himalaya. This zone of localized uplift prevents rapid headward reatreat of sream profile so that the front of the Higher Himalayan can remain linear in map view. (Lave and Avouac, 2001)
Tibet India
Environments • Orthogonal convergence • Behind-the-arc contraction zones • Tien Shan • Andes • Papua New Guinea and Irian Jaya • Eastern Indonesia • North-Panama deformed belt • Northeastern Japan
Environments • Orthogonal convergence • Behind-the-arc contraction zones • Auxiliary faults in strike-slip systems • Coast and Transverse ranges, California • New Zealand • Qilianshan, China
Transpressional Transtensional
GPS display a component of strain not parallel to the San Andreas fault. This is accommodated mostly by thrust faults in the LA region. From the Southern California Integrated GPS Network, courtesy of Ken Hudnut
Most topography in the region is the result of activity on these thrust faults
1994 1987 For example, the 1987 and 1994 earthquakes alerted us to the presence of active blind thrusts within the metro region From JPL’s SRTM mission
Environments • Orthogonal convergence • Behind-the-arc contraction zones • Auxiliary faults in strike-slip systems • Shields • Australia • eastern Canada • India