Abstract:
The Yuqia eclogite-type rutile deposit is located on the west side of the northern margin of the Qaidam Basin UHP metamorphic belt. And it is the first ultra-large rutile deposit found on the Tibetan Plateau. In order to study the ore-controlling factors and metallogenic mechanism of this deposit, the authors conducted detailed field geological survey and petrographic study. The characteristic minerals in the eclogite of the deposit were analyzed by electron microprobe analysis. It is shown that the garnets of coarse-grained high-Ti eclogite have preserved relatively complete compositional zoning; from the core to the edge, the garnet has a distinct zonality in chemical composition, type and granularity of mineral inclusions. However, the mineral particles in the fine and gneiss low-Ti eclogite are smaller, and the composition of the garnet is poor. Characteristics of
p-
T evolution of Yuqia eclogite show that it experienced a clockwise evolutionary trajectory from the temperature and pressure rise of the deep subduction stage to the temperature rise and pressure decrease of the early exhumation stage and then to the decrease of both temperature and pressure. The eclogite belongs to the metamorphic mineral assemblage with the preservation of the growth zone, which suggests that the formation of eclogites went through a dynamic process of relatively rapid subduction and reentry exhumation.