柴达木盆地北缘塔塔楞环斑花岗岩的SHRIMP年龄

The SHRIMP Age of Tatalin Rapakivi Granite at the North Margin of Qaidam Basin

塔塔楞环斑花岗岩套侵位于柴达木北缘加里东构造带中,面积达350km2,是我国最大的环斑花岗岩体。锆石SHRIMPU-Pb法测得其地质年龄为440±14Ma,属加里东期,晚于柴北缘UP-UPF榴辉岩、岛弧火山岩及俯冲型花岗岩的时代约30-50Ma左右,形成于造山运动由挤压造山向后碰撞拉张体制的转折构造环境,代表了加里东运动的终结。榴辉岩—岛弧型火山岩—俯冲花岗岩—环斑花岗岩共同构成了柴北缘构造岩浆演化的完整旋回。塔塔楞环斑花岗岩的发现和时代的准确确定对认识柴北缘加里东构造带的构造演化特征和物质组成具有重要科学意义,为阐明柴达木北缘加里东运动的构造演化和结束提供了重要的岩石学约束。

Tatalin rapakivi granite suite is located in Caledonian tectonic belt of the north margin of Qaidam Basin with an area of 350km2 , which is the biggest rapakivi granite mass in China. The geologic age of 440 ±14Ma is measured by the zircon SHRIMP U-Pb dating, which belongs to Caledonian period and is 30- 50Ma later than UP-UPF eclogite, volcanic rock of island arc and subduction granite. It formed under the hinge tectonic environment of orogeny from compressional orogeny to collision extension and shows the end of Caledonian orogeny. Eclogite-volcanic rock of island arc -subduction granite-rapakivi granite commonly forms the complete cycle of the tectonic magmatic evolution at the north margin of Qaidam Basin. The discovery and accurate confirmation of Tatalin rapakivi granite are of important scientific significance to understand the tectonic evolution characteristics and physical makeup of Caledonian tectonic belt at the north margin of Qaidam Basin and provide the important evidences in lithology for explaining the tectonic evolution of Caledonian tectonic belt at the north margin of Qaidam Basin.