新疆东昆仑阿其克库勒湖西南缘蛇绿岩——铬铁矿证据及其构造环境探讨

CHROMITES EVIDENCE FOR OPHIOLITE AT THE SOUTHWESTERN MARGIN OF AQIKEKULE LAKE AND ITS TECTONIC ENVIRONMENTAL DISCUSSIONS, EASTERN KUNLUN MOUNTAIN, XINJIANG

新疆东昆仑阿其克库勒湖西南缘蛇绿岩沿近东西走向的昆中断裂出露,以构造岩片的形式夹持于泥盆纪和志留纪地层中,由变质橄榄岩、堆晶岩和火山岩三部分组成。对变质橄榄岩中的铬铁矿成分分析证实了它们属蛇绿岩的成员,并且铬铁矿的Cr#=Cr/(Cr+Al)为0.59～0.65,指示蛇绿岩经历了从洋中脊到俯冲带环境的演化,形成机制为岩石-熔体反应机制。

Outcropping along the Kunzhong fault in an approximately east-to-west strike, the ophiolite at the southwestern margin of Aqikekule lake, east Kunlun mountain, Xijiang, is located between the strata of Devonian and Silurian as a tectonic slice. The ophiolite is composed of such three parts as metamorphic peridotites, cumulates and volcanic rocks. The analyses of chromites composition sampled from the metamorphic peridotites indicate that they do belong to ophiolites, and the Cr# (= Cr/(Cr+Al)) of chromites from this ophiolite is 0.59～0.65, which infer that the ophiolite had undergone the environmental evolution from mid-ocean to supra-subduction zone and resulted from rock-melting reaction.