皖南元古宙基底两套绿岩特征及地壳演化

CRUST EVOLUTION AND THE CHARACTER OF TWO GREENSTONE SUITES IN PROTEROZOIC BASEMENT SOUTH ANHUI

皖南江南隆起区出露的前寒武系变质杂岩研究的新资料，进一步揭示了岩石成因、时代、地球化学组成和地壳演化特征。重新厘定了上溪群为古元古代，由一套安山岩、英安岩、流纹岩及层凝灰岩经变质而成，它构成了江南-雪峰隆起高原科马提绿岩的一部分。地球化学组成具原始地幔特征。其上的新元古代蛇绿岩套，是由10亿年左右的一套橄榄-蛇纹岩、辉橄岩、辉长岩、堇青石斜长闪长岩、辉绿岩、细碧角斑岩、硅质-碧玉岩组成。其地球化学组成为亏损地幔，呈典型的活动大陆边缘的大洋盆生长层。不整合覆于老地层之上。上述两套岩层性质的确定．证明了元古宙上、下两套绿岩是组成华南基底的主要生长层。由地幔柱活动所引起的两次突变事件形成的火山物质组成了扬子地块的中下地壳。因此，地球系统的演化主要是由地球内部的物质交替所推动，它强烈的影响气圈、水圈、生物圈，也推动生物的前进演化。鉴于此，皖南元古宙绿岩的新资料，无疑是十分重要的，对正确认识华南的壳-幔演化有一定的参考价值。

The studies of the Cambrian metamorphic rock explosed in Jiangnan uplift South Anhui show the character of rock genesis, time, geochemical component and crust evolution.Shangxi qun is redefined as the Proterozoic, which consists of a series of metamuphic andesite dacite, rhyolite and tuff layers. Shangxi qun forms a part of komatiite greenstone is JiangnanXiefeng uplift plateau. The geochemical components of the qun possess character of primary mantle. The overlying late Proterozoic ophiolite suite is composed of peridotite-serpentinite,gabbro, pyrolite , cordierite , plagiodiorite , diabase , spilite-kerasophyte , siliceous jasper rock. The geochemical components of the Proterozoic ophiolite suite were derived from depleted mantle,which represents the typical growth layer of ocean basin along the continental margins. The late Proterozoic ophiolite suite unconformably overlny early Proterozoic ophiotite suite.The determination of above two rock layers proved that main growth layer of South China basement is composed of Proterozoic upper and lower greenstone suites. Two huge catastrophs resulted in the formation of volcanic materials by plume activity. The latter generated the middle-lower crust of Yangtze block.The evolution of earth spetem is mainly promoted by materials aternation in inner earth,which heavily affected gas-sphere. watersphere and biosphere.Based on the above-mentioned hews it is undoubtedly important that the new data of Pruterozoic greenstone in South Anhui provide the referential value for understanding the evolution of crust-mantel South China.