西昆仑塔什库尔干大河口一带斜长角闪岩岩石地球化学特征及成因探讨

Study on Geochemical Characteristics and the Origin of Amphibolite in Dahekou Area in Tashkurgan in Western Kunlun

摘要:

塔什库尔干县马尔洋乡大河口一带发育灰绿色斜长角闪岩，全岩地球化学分析结果显示其属于钙碱性系列，原岩为基性火山岩，形成于会聚阶段的板块边缘。锆石LAICPMS UPb年龄为512±3.8 Ma，揭示其形成时代为早古生代，与区域上康西瓦构造结合带的形成同期。据此推断，大河口斜长角闪岩的形成与古特提斯洋演化密切相关，是原特提斯洋俯冲消减的产物。

Abstract:

Grey-green amphibolite is developed in Dahekou area of Maeryang town in Tashkurgan county. As showed by geochemical analysis, it belongs to calc-alkaline series. The original rock may be basic volcanic rock, which formed at the plate margin of centralizing period. The LA-ICPMS U-Pb age of zircon is 512+3.8 Ma, which reveals that the zircon is formed in the early Paleozoic and coincided with the formation of Kangxiwa structural junction zone in the region. It is inferred that the formation of amphibolite in Dahekou area is closely related to the evolution of Paleo-Tethyan ocean. It is the product of the subduction of original Tethyan ocean.