科研之友
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摘要
The existence of Paleoproterozoic basement in the western Yunnan area has been a hot topic of debate. In this study, large amounts of inherited zircons of the granite porphyry in the Taohua area were selected to use for the SHRIMP U-Pb dating. The Taohua granite porphyry that has geochemical signatures of island arc granite and was formed in a late orogenic to late-collision-process, which possibly related to remelting magmatism induced by resubduction of the detached Jinshajiang oceanic crust and enriched lithospheric mantle domain or by the partial melting of the thickened crust. Inherited zircons were divided into two types: core inherited zircon presented in cores of magmatic zircons with dense oscillatory zones, and subrounded shape inherited zircon. Based on the dating results, the magmatic zircons have an age of approximately 36. 35 +/- 0. 35Ma, the inherited core zircons have ages ranging from 167Ma to 891 Ma, whereas the subrounded shape inherited zircons record two group zircons with mean ages of 1851 +/- 22Ma and 2499 +/- 32Ma, respectively. The new dating results of the zircons from the Taohua granite porphyry indicate that there are not only records of later Paleozoic arc magmatism related to eastward subduction of the Jinshajiang ocean plate and of the Neoproterozoic rift magmatism, but also Early Proterozoic zircon and magmas in the Taohua area, western Yunnan. Moreover, the 1. 8Ga and 2. 5Ga zircon groups were originated from the ambient Shigu schist, and the Shigu schist possibly has a 2. 5 similar to 1. 8Ga crust basement. This is to say that there is Early Paleoproterozoic basement in the western Yunnan area.
- 出版日期2015-9
- 单位中国科学院地质与地球物理研究所兰州油气资源研究中心; 中国科学院地质与地球物理研究所; 中国科学院大学; 中国地质大学（北京）
