Stratigraphy and Geochemical Features of the Early Miocene Bimodal (Ultrapotassic and Calc-alkaline) Volcanic Activity Within the NE-trending Selendi Basin, Western Anatolia, Turkey

Turkish Journal of Earth Sciences

YALÇIN ERSOY¹ 

关键词: Western Anatolia;    lamproite;    ultrapotassic volcanism;    bimodal volcanism;    continental extension;   

学科分类：地球科学(综合)

来源: Scientific and Technical Research Council of Turkey - TUBITAK

【 摘 要 】

Western Anatolia has experienced thickening and orogenic collapse subsequent to the Eocene continent-arc collision. The early stage of the post-collisional volcanism in the region was thought to have produced widespread lavas and pyroclastic deposits of calc-alkaline basaltic andesite to rhyolite composition. However, in the Selendi Basin, one of the NE-trending basins in western Anatolia, there are two distinct volcanic unit compositions associated with the Lower Miocene sedimentary rocks: (1) a calc-alkaline, high-potassic felsic unit; and (2) alkaline, ultrapotassic lamproitic units, i.e. both are bimodal in character. The calc-alkaline felsic volcanic rocks (Eğreltidağ volcanic unit) are composed of wide-spread pyroclastic rocks and lava flows, whilst the ultrapotassic-lamproitic mafic rocks (Kuzayır lamproite) consist of small-volume syn-sedimentary lava flows. The geochemical characteristics of the Kuzayır lamproite are similar to those of the ´Mediterranean lamproites` that were widely produced in post-orogenic tectonic settings. A temporal and spatial association between these volcanic units clearly describes a post orogenic bimodal volcanic activity. The data also imply that the continental extensional tectonic regime in western Anatolia began, at least, in the Early Miocene, and produced not only calc-alkaline felsic activity but also mantle-derived alkaline, ultrapotassic volcanic rocks.

【 授权许可】

Unknown