【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。更多还原

【Abstract】 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.更多还原