Evidence for Stepwise North to South Growth of the Cenozoic Central Anatolian Plateau (Turkey)

Abstract:

Today, large internally drained lakes are forming within the high elevation, low relief regions of Earth’s three major orogenic plateaus - the Andes, Tibet, and Anatolia-Iran. These internally drained basins represent the largest surface expression of active surface deformation processes, yet the geoscience community lacks first order understanding of how, when, and where these sizable physiographic features form. We synthesize existing geologic data and present new zircon U-Pb data indicating that red, gypsum-rich siltstones and sandstones within the Central Anatolian Çankiri basin were deposited in early Oligocene times. Lower Miocene grey-tan evaporites, siltstones, sandstones, and conglomerates overlie the Oligocene strata above an angular unconformity. Adakitic magmatism within the Galatean volcanic province, located immediately west of the Çankiri basin occurred in early Miocene times and was likely coeval with folding of early Oligocene gypsum-rich red beds within the Çankiri basin. We hypothesize that the first-order tectonic evolution of the Çankiri basin and Galatean volcanic province represents the surface manifestation of early Oligocene growth followed by early Miocene removal of a dense eclogitic crustal root that formed as a result of the ongoing intercontinental collision between the Kirşehır Block and Central Pontides. If correct, our results indicate uplift of the northern region of the Central Anatolian Plateau took place as much as ~25 Myr prior to its southern counterpart.