Uplift and Exhumation in Central Anatolia: New Results from Low-Temperature Chronometry in a Deeply Incised Granite in the Central Tauride Mountains, Turkey

Abstract:

The timing of late Miocene to present uplift of the southern margin of the Central Anatolian Plateau (central Tauride Mts) was recently established with biostratigraphic and surface exposure data from Neogene marine sedimentary rocks and Quaternary terraces (Schildgen et al., 2012). The presence of a deeply incised Eocene intrusion (Horoz granitoid) offers the opportunity to use uranium-based low temperature dating techniques to determine the timing and rates of exhumation in response to this uplift.

The Horoz granitoid (∼6 x 2 km) has a sharp intrusive contact between the lower Paleozoic to Upper Cretaceous platform carbonates of the Tauride belt (Bolkar Mountains) in the south and the Upper-Cretaceous Alihoca ophiolites and ophiolitic mélanges in the north, and is bounded in the east by the strike-slip Ecemiş Fault Zone. The intrusive body is an ENE–WSW-trending, sill-like shallow-seated pluton that crystallized at 49-55 Ma (zircon U–Pb: Kadioğlu & Dilek, 2010, Parlak et al., 2013).

The intrusion is exposed along a steep NE-SW valley and is unconformably covered by slope debris and alluvial terraces along its southern edge. Six samples were collected along an E-W transect over 900m of elevation. Apatite (U-Th)/He ages range from ~16 Ma at the highest elevation sample (1900 m) to ~9 Ma for the lowest (1000 m), following a linear age-elevation trend. Apatite fission track ages show a similar trend, but with older ages from ~38 Ma at the top of the transect to 31 Ma at the bottom. The Horoz granitoid records two main pulses of cooling: (1) an initial stage at ~38-31 Ma, possibly linked with a regional event that is recorded in other crystalline rocks in Central Anatolia; and (2) a later stage that may correspond to at least ~2 km of erosion-related exhumation associated with late Miocene uplift of the southern margin of the Central Anatolian Plateau.