Dating of low-grade high-pressure Metamorphism in the Afyon Zone; W-Anatolia

点击翻译按钮获取中文摘要

During the first field based period of this grant (2007-2008) extent and distribution of low-grade high-pressure rocks in SW Turkey and along the entire Afyon Zone and the Bitlis Massif in Eastern Anatolia was confirmed. The findings demonstrate the continuous existence of a major blueschist belt running south of the Kirşehir block, that forms the Central Anatolian plateau. These findings, their extent and the relation towards the Tavsanli zone in the north as well as the Taurids in the South clearly plead for a branch of the Neotethys south of the Kirsehir block, a fact that is highly contested by many Turkish colleagues. In the context of successively younger ages found in HP metamorphism of Western Turkey form North to South, we propose to determine the age of metamorphism for constraining the exhumation history of the Afyon HP belt. This includes the Lycian nappes and parts of the cover sequence of the Menderes Massif. The Afyon HP belt is characterized by Mg-Fe-carpholite bearing, blueschist facies metapelites. We found Mg-Fe-carpholite as rock forming mineral in a metamorphosed fluvio-deltaic sequence. Fe-Mg-carpholite occurs exclusively in albite free rocks, mostly associated with phengite. Thus, Na must have been leached completely, while K remained in these rocks. We therefore started performing lithofacies and geochemical investigations for understanding the pre-metamorphic weathering/alteration and sedimentation conditions which led to rock compositions prone to form Mg-Fe-carpholite. These investigations will continue during this grant period.