Extensional Basins in Western Anatolia Extended Terrane, Turkey: Their Age, Structural Development and Economic Significance

Abstract

The Cenozoic post-collisional extension is responsible for the formation of many extensional basins in different parts of the West Anatolia Extended Terrane (WAET) in Turkey. The southern part of the WAET contains several sedimentary basins formed by normal-oblique slip fault movement along the Southwestern Anatolian Shear Zone which were initiated in the Late Oligocene. The basins contain limestone, ophiolite and low grade metamorphic rock fragments eroded from the Menderes Core Complex (MCC) during its early history of exhumation in Oligocene. The western and northern part of the WAET contains north-south trending basins. These basins started to form in the Early Miocene related to the north directed extension. They were formed along mainly two structural features (a) NE-SW trending Izmir-Balikesir Transfer Zone (IBTZ) and (b) the MCC. The age of the volcanic intercalations and related sediments of the basins along the IBTZ show a clear younging from NE to SW with no remarkable unconformity. This suggest that they were formed as mostly strike-slip fault during the slab rollback which is the major cause of extension in Miocene. The Alasehir and Buyuk Menderes Grabens are located in the central part of the WAET. They contain sedimentary rock units time-equivalent to the sedimentary units in the north-trending basins. They were developed in early to middle Miocene on the northern and southern flanks of the MCC, respectively, as supra-detachment basins. To date, the only hydrocarbon discovery and negligible production is from the Miocene sediments of the Alasehir Graben. There has not been much exploration in the Buyuk Menderes Graben. The N-S trending basins are rich in borate deposits. The WAET is also rich in terms of geothermal energy due to its extensional tectonics setting and high heat flow.

AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014