Metallogenetic regularity of rare-metal pegmatites in East Qinling
East Qinling,the eastern segment of the North Qinling orogen,is one of the most important rare-metal metallogenic belts in China,hosting almost 7000 pegmatite dikes that are mainly confined within four pegmatite districts(namely Luanzhuang,Guanpo,Longquanping and Shangnan).In this contribution,we reviewed the spatial distribution,ore occurrence,metallogenic ages and ore-forming conditions of the pegmatites,and further explored the metallogenetic regularity of the rare-metal pegmatites in East Qinling.In terms of spatial distribution,most pegmatites with Li,Be and other rare metal mineralization are distributed along the Luanchuan-Zhuxia and Caichuan faults to north of the Huichizi granitic pluton,and less in the Shangnan area(e.g.,Daweiyuan,Fenghuangzhai,etc.)that is located to the north of the Shangdan sutrure.Such distribution pattern of the rare-metal pegmatites is different from the regional zonation with the Huichizi pluton as the center that were proposed by previous studies.The rare-metal pegmatites predominantly formed from 445Ma to 370Ma.Although there is an age overlap(440～400Ma)between the rare-metal pegmatites and the Paleozoic granites in East Qinling,the geochronological and zircon Hf isotope data indicate that those exposed granitoids are unlikely the parental granites to the majority of the rare-metal pegmatites.Moreover,the zircon Hf isotope data also suggest that the anatexis of the Qinling Complex likely resulted in the rare-metal pegmatites at Guanpo and Shangnan.The lithium pegmatites at Shangnan exhibit higher zircon εHf(t)values and younger tDM2 ages than those at Guanpo,indicating the diversity of the soure regions for the rare-metal pegmatite.The distribution pattern of the rare-metal pegmatites is intimately related to the subduction-collision of the North Qinling orogeny,and the formation ages of the pegmatites also correspond to the tectonic evolution.This implies a tectonic-anatexis-metallogenesis model,and the rare-metal pegmatites were emplaced at multiple stages including the collision and extension stages of the North Qinling orogen during the Paleozoic tectonic evolution.
万方数据
维普
