Zircon U-Pb ages and geochemistry of the monzonitic granite in Rongguo area in Middle Gangdise Belt |
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| Authors: | HU Lin XU Gang LIU Daming |
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| Institution: | Northwestern Sichuan Geological Team, Bureau of Geology and Mineral Resources Exploration and Development of Sichuan Province, Mianyang 621000, China |
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| Abstract: | In order to determine the geochronology, petrogenesis and tectonic background of the monzonitic granite in Rongguo area, the authors conducted the research on petrology, LA-ICP-MS zircon U-Pb geochronology and geochemistry. The results show that the zircons from the monzonitic granite are of magmatic genesis, and the zircon 206Pb/238U dating is (69±1) Ma, belonging to the Late Cretaceous. Al2O3, Na2O, K2O contents and K2O/Na2O ratio are 13.83%~14.41%, 3.68%~3.94%, 4.28%~4.35% and 1.08~1.18 respectively. The average aluminum saturation index (A/CNK) is 1.02, belonging to the weak peraluminous series. The rocks are enriched in LILE (Rb,U,K), strongly depleted in HFSE (Nb, Ta, Ti, etc.). Combined with the study of regional tectonics, the authors insisted that magma activity had not stopped from 80 to 69 Ma. The rock mass is the magmatic product of the subduction of the Neo-Tethys Ocean, forming in the orogenic environment during the whole orogenic movement period. |
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| Keywords: | monzonitic granite geochemistry LA-ICP-MS zircon U-Pb age Gangdise |
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