皖南新元古代花岗岩的SHRIMP锆石U-Pb年代学、元素地球化学和Nd同位素研究  

SHRIMP U-Pb Zircon Geochronological,Geochemical and Nd Isotopic Study of the Neoproterozoic Granitoids in Southern Anhui

作　　者：李献华[1] 李正祥[2] 周汉文[3] 刘颖[1] 

机构地区：[1]中国科学院广州地球化学研究所,510640 [2]西澳大利亚大学大地构造国家研究中心 [3]中国地质大学地学院,武汉430074

出　　处：《地质论评》2002年第S1期8-16,共9页Geological Review

基　　金：国家杰出青年科学基金项目(编号49725309);国家自然科学基金重点项目(编号40032010-B)资助成果

摘　　要：高精度的SHRIMP锆石U-Pb定年结果表明,皖南(扬子块体东南缘)许村花岗岩的形成时代为823±8 Ma。矿物组合、岩石化学、元素和同位素地球化学特征表明皖南新元古代花岗岩均为过铝质S型或CPG型花岗岩,其源岩主要是富长石、贫粘土的砂屑岩,地壳平均存留年龄为1.6～1.5 Ga(类似于区域中元古代双桥山群变质岩),花岗岩是砂屑岩在800～850℃、含水条件下部分熔融形成的。皖南新元古代花岗岩不是"晋宁早期造山运动"的产物,而很可能是华南约825 Ma地幔柱活动导致地壳重熔的产物。High-precision SHRIMP U-Pb zircon analysis indicates that the Xucun granitoid in southern Anhui, in the southeastern Yangtze Block formed at 823±8 Ma. Mineralogical, petrographic and geochemical characteristics indicate that the southern Anhui Neoproterozoic granitoids are peraluminous, S-type or CPG type granodiorites. They were derived from a clay-poor, plagioclase-rich psammitic source having crutsal residence ages of 1. 5～1.7 Ga, similar to the regional Mesoproterozoic Shuangqiaoshan metasediments. The granitoids were generated by partial melting under vapour-present conditions at 800～850℃. It is suggested that the southern Anhui Neoproterozoic granitoids were formed by crustal anatexis above a mantle plume at ～825 Ma in South China, rather than formed during the early Jinningan orogeny as previously thought.

关 键 词：新元古代 花岗岩 锆石U-Pb年龄 元素地球化学 ND同位素 皖南 

分 类 号：P597.3[天文地球—地球化学]