Ushba, western Greater Caucasus, Georgia
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Structural Geology & Neotectonics of the Greater CaucasusThe Greater Caucasus Mountains, located between the Black and Caspian Seas, define the northern margin of the Arabia-Eurasia collision zone, a broad collision zone that extends from the eastern Mediterranean to Afghanistan. The Greater Caucasus accommodate nearly all orogen-perpendicular shortening between Arabia and Eurasia [Jackson, 1992; Reilinger et al., 2006], and low-temperature thermochronology data from the range suggest that the orogen is young and evolving rapidly, with a change in exhumation rate at ~5 Ma [Avdeev & Niemi, 2011]. However, the first-order structural architecture and total shortening recorded within the range remain poorly constrained. Developing a model for the locus and magnitude of shortening accommodated within the orogen is critical for understanding the processes at work in the evolution of this young continental collisional orogen.
My current work combines 1:100,000-scale structural mapping with petrographic and stratigraphic observations to construct tectonostratigraphic columns and balanced cross sections along 100+ km transects across the orogen. In addition, I am using low-temperature thermochronology (primarily apatite [U-Th]/He) to assess the validity of these cross sections and begin to investigate activity across major structures. Finally, my project includes a neotectonic investigation of actively deforming river terraces in the foreland basin south of the western Greater Caucasus, and kinematic modeling of deformation to better understand structural geometry and shortening rates. These results allow me to assess the total crustal shortening and geologic shortening rates recorded in the Greater Caucasus orogen, and to begin to assess the extent to which the shortening currently visible in the geologic record is representative of the total shortening accommodated within the orogen. |
Balanced cross section along the Aragvi/Terek Traverse, Central Greater Caucasus. From Trexler et al. (in prep, Tectonics)