LA-ICP-MS Zircon U-Pb Ages,Geochemical Characteristics,and Geological Significance of Pre Cambrian Paleoproterozoic Granite in the Northern Margin of Tarim Basin
The Tarim Craton has experienced events related to the evolution of the Columbia supercontinent.The con-vergence and fragmentation of the Columbia supercontinent mainly occurred in the Paleoproterozoic(1800 Ma～2500 Ma),accompanied by strong crustal accretion events,and has received widespread attention from geologists.There is still con-siderable controversy over the timing of the convergence and fragmentation of the Colombian supercontinent.Xingditag area is located in the northeast margin of Tarim Basin,where a large number of Precambrian magmatic rocks are ex-posed.It is a natural laboratory for studying the evolution of Columbia supercontinent.Through geochemical analysis of the granite(quartz diorite,granodiorite,granite)in this area,it was found that it is a rock combination formed by the evo-lution of homologous magma,belonging to the high potassium calcium alkaline rock series and quasi aluminous granite.Enriched with large ion lithophilic elements(LILE)such as U,Sr,K,Ba,etc.,slightly depleted with Th,Rb,etc.,and strongly depleted with high field strength elements(HFSE)such as Ta,Nb,P,Ti,etc.,exhibiting typical VAG characteris-tics.The distribution patterns of trace and rare earth elements are similar to those of the upper and middle crust.Formed in a subduction and subduction environment of the plate.Through zircon U-Pb dating,a weighted average age of 206Pb/238U was obtained,ranging from 1930±11 Ma to 1944±9 Ma,indicating a late Paleoproterozoic period.Based on the regional tectonic background,it is believed that this period of granite may be related to the subduction of the North Tarim towards the South Tarim and the occurrence of land land collision,ultimately forming a unified Tarim plate event,which is a dynamic response to the aggregation of the Columbia supercontinent.
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