新疆东天山色尔特能蛇绿岩地球化学特征及构造环境分析

Geochemical Characteristics and Tectonic Environment of the Ophiolite in Seerteneng,in Eastern Tianshan,Xinjiang

色尔特能蛇绿岩位于大南湖岛弧西段,康古尔断裂北侧,由纯橄岩-辉橄岩-橄辉岩-辉石岩和辉长岩组成。色尔特能蛇绿岩中辉长岩为钙碱性-低钾拉斑系列,稀土元素配分曲线略呈左倾,重稀土较轻稀土轻微富集,与N-MORB特征相似。Eu正异常明显,富集Rb,Ba,Sr,U,Nb,亏损高场强元素Th、Ta,为地幔尖晶石二辉橄榄岩部分熔融的产物,部分熔融程度为10%~15%。色尔特能-康古尔南蛇绿岩属MORB型蛇绿岩,形成时间为晚寒武—早奥陶世,构造侵位时间为晚石炭世之前。

Seerteneng mafic-ultramafic rocks located in the the western segment of Dananhu island arc and northern part of Kangur suture zone has the composition of dunite,pyroxene peridotite,pyroxenite and gabbro.In order to investigate tectonic environment of the ophiolite,the petrology and geochemical studies to the gabbro were carried out in this paper.The gabbro are attributed to calc-alkalic series to low K tholeiite series.The chondrite-nomalized REE pattern shows a typical light rare earth depletion,heavy rare earth enrichment relatively,characteristics of N-MORB and Eu positive anomaly.The race element spider diagram indicates that gabbro is relatively rich in Rb、Ba、Sr、U、Nb,and depleted in Th、Ta,which may have been originated from 10%-15%partial melting of spinel lherzolite.The ophiolite belt from Seerteneng to the southern kangur belongs to MORB ophiolite,formed in the late Cambrian to lower Ordovician,accomplished the emplacement before late carboniferous.