Genesis and Geological Significance of Post-Collision Granites in South Altun
The polarity of Early Paleozoic ocean-continent transformation in South Altun has been an issue recently.However,detailed petrological evidence for the exhumation of the deep subducted continental crust is still lacking.In this paper,it researches petrological,geochemical,zircon U-Pb chronological and Lu-Hf isotopic characteristics of the northern Manya complex,to discuss its source and tectonic environment,and reveal magmatic response to the Early Paleozoic tectonic evolution.The 458-420 Ma granites have similar material source and magmatic source,resulting from the similar ranges of ε Hf(t)and tDM2 values,and shoshonitic characteristics such as rich in alkali and K,and lack of Ti and Fe.The 458-453 Ma granites were formed by decompression melting of deep-subducted continental crust,which were transported to the upper crust by exhumation.The 451-420 Ma granites were product of partial melting of lower crustal materials triggered by underplating of mantle-derived magma in a post-collisional extensional environment.Thus,exhumation of the deep-subducted continental crust completed at<453 Ma,and the orogenic belt were in late orogenic post-collisional environment at<451 Ma.
South AltynEarly Paleozoicexhumationpost-collisionalpetrologygeochemistry
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