Characteristics and zircon SHRIMP U-Pb ages of the arc magmatic rocks in Mazar, southern Yecheng, West Kunlun Mountains.

Abstract

Arc magmatic rocks in the Mazar area was discovered and defined during the 1∶250000 regional geological survey of the Mazar Sheet. The arc magmatic rocks in the Mazar tectonic melange zone contain some important information of the consumption process of old oceanic crust. The arc magmatic rocks are dominantly composed of intermediate-acid intrusive rocks and volcanic rocks and have island arc rock associations and geochemical affinities. Zircon SHRIMP U-Pb dating of hornblende-quartz diorite in the arc magmatic rocks yielded an age of 338±10Ma, indicating an Early Carboniferous age. The discovery of the arc magmatic rocks in the Mazar area has not only supported the idea of the appearance of the Mazar-Kangxiwar ocean (Paleo-Tethys) in the Late Paleozoic, but also suggested that this ocean had begun subduction and consumption by the Carboniferous.