Abstract:
On the basis of geological mapping on the scale of 1∶50000 in the Buqingshan area on the southern margin of the East Kunlun Mountains and by means of detailed field section measurement and rock assemblage analysis as well as LA-ICP-MS zircon U-Pb dating, the authors have divided the melange into two parts, i.e., matrix and tectonic melange rock blocks. The includes metamorphic basement rock block, oceanic crust type rock block and island-arc type rock block, in which the ocean-crust type rock block can be further divided into Early Paleozoic ophiolite(516.4±6.3Ma), Late Paleozoic ophiolite(332.8±3.1Ma)and seamount or island basalt, whereas the island-arc type rock block is composed of Caledonian island-arc type granodiorite(441.1±6.3Ma)and middle-acid volcanic rocks. It is thus concluded that there are two typical rock assemblages of paleo-ocean basin's spread and subduction in Buqingshan ophiolite complex belt, which represent the formation and evolution of eastern Proto-Tethys and eastern Paleo-Tethys respectively. The results provide new evidence for the study of evolution process of East Tethys.
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