NEOTECTONIC EVIDENCE OF ALONG-STRIKE VARIATION OF STRAIN IN THE GREATER CAUCASUS MOUNTAINS

The Greater Caucasus (GC) Mountains are an ENE-trending range that extends for over 1000 km between the Black and Caspian Seas along the northern edge of both the East Anatolian Plateau and Arabia-Eurasia collision. GPS surveys indicate NW-SE convergence rates across the range systematically increase from ~2mm/yr in the W to ~14mm/yr in the E due to counterclockwise rotation of the East Anatolian Plateau relative to stable Eurasia to the north. It remains unclear, however, if this variability is a short-lived aspect of the deformation field or represents the long-term kinematics of the collision. If along-strike variation in shortening rate is long-lived, then total shortening should be greater at the E end of the range that at the W, and folds in the forelands of the eastern GC should have greater amplitudes, longer wavelengths, and be more incised than folds in the forelands of the western GC, but no comprehensive comparison has yet been made between neotectonics of the W and E segments of the range and forelands. To address this problem, we used a new, interactive, virtual reality mapping program called the Real-time Interactive Mapping System (RIMS) to construct a neotectonic map of the N and S flanks of the GC foreland. In RIMS, geo-referenced imagery is draped over a digital elevation model allowing features to be observed and mapped directly on the terrain display in real-time. In addition to geo-referenced and attributed line mapping, bedding attitudes can also be measured. Using RIMS with Landsat ETM+ (28.5 m pixels) imagery draped over the SRTM90 (90 m pixels) DEM we have found isolated remnants of uplifted, tilted, and incised terrace surfaces are present along the length of the range, but are particularly well developed on the northern flanks of the GC. This preliminary mapping suggests that shortening is concentrated in the E foreland of the GC in accordance with the GPS velocity field. Geomorphic mapping in this region identified active folds within linear ridges parallel to the GC strike. Along-strike variation in preservation of folded terrace surfaces suggests that some folds are laterally propagating. These observed along-strike differences in the geomorphic nature of the GC forelands suggest that counterclockwise rotation of the East Anatolian Plateau is a long-lived aspect of the kinematics of the orogen.