The Magmtic Response of the Cenozoic Orogeny for the Southwest Tian Shan:A Case For Cenozoic Volcanic Rocks in Piqiang Basin,Xinjiang
Piqiang basin is a Cenozoic tectono-volcanic depression located in Southwest Tian Shan,Xinjiang,NW China.There are four volcanoes and some dykes in Piqiang basin,and several dykes are connected with volcanic necks.This paper studied these volcanic rocks with petrographic and geochemical analysis method.The results show that these volcanic rocks are the mantle-source partial melting products of primary magma and these are composed of tephrites,basanites and basalts,and display that these volcanic rocks are from intraplate orogenic setting,and they lack evident fractional crystallization trend.With volcanic rocks geochemical data of Tuyun basin,we discuss that trigger mechanism of magma ranges in Southwest Tien Shan,and suggest that regional lithosphere delamination is the important magmatic mechanism.