Development history of the foreland plate trapped between two converging orogens; Kura Valley, Georgia, case study
M. Nemčok, B. Glonti, A. Yukler, B. Marton, 2013. "Development history of the foreland plate trapped between two converging orogens; Kura Valley, Georgia, case study", Thick-Skin-Dominated Orogens: From Initial Inversion to Full Accretion, M. Nemčok, A. Mora, J. W. Cosgrove
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Structural, sedimentological, well and seismic data from the Kura basin show that the geometry of deformation has been largely determined by thick-skin structures occurring along margins of depressions filled with upper Oligocene–lower Miocene Maykop formation, flanked by highs without Maykop record. Thin-skin structures are detached inside the shaly Maykop formation and inside shale horizons of the Sarmatian–Pontian section. The main shortening took part during Sarmatian–Pontian, followed by subordinate shortening during Akchagylian–present. The thick-skin architecture formed first, reactivating pre-existing rift grain on the foreland plate that refused to flex underneath the load of advancing orogens. The thin-skin architecture developed subsequently, deforming thick-skin structures. During the Oligocene–early Miocene, the foreland basin behaved as a flexural basin, reacting by prominent fill asymmetry to Oligocene loading by the advancing Lesser Caucasus and earliest Miocene–early Sarmatian loading by advancing Greater Caucasus. Subsequently, the basin recorded only vertical movements responding to new orogen loading events. Each loading event was recorded by a shift of marine depositional environments northwestwards, up the SE-plunging Kura Valley. Conversely each quiescence period was recorded by their retreat southeastwards, towards the Caspian Sea.
Discussion of the observations from geological and seismic cross sections, additional outcrop photos and data, lithostratigraphic charts of the Greater Caucasus, the Adjara–Trialet and the Eastern Pontides, heat flow map and of the Kura basin, depth distribution of earthquake hypocentres for the Kura basin region, and Apulia map and cross section are available at http://www.geolsoc.org.uk/SUP18626
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Thick-Skin-Dominated Orogens: From Initial Inversion to Full Accretion
This volume studies the driving dynamic for thick-skin tectonics. It evaluates the role of various factors that control the development of thick-skin architecture. The studied driving dynamics include individual plate movement rates, overall convergence rates, orogen movement sense with respect to mantle flow and pro-wedge versus retro-wedge location. Numerous internal factors that influence the architecture of thick-skinned dominated orogens have been considered. These include the role of the rheology of the deforming layers, the presence or absence of potential detachment horizons, basement buttresses, crustal thickness variations, inherited strength contrasts and the impact of pre-existing anisotropy in thick-skin orogenic deformation. External factors discussed include the role of both syn-tectonic erosion and deposition in deformation.
The study areas begin with worldwide examples and close with a detailed coverage of the Northern Andes natural laboratory, which is characterized by particularly robust data coverage.