口门子南地区中—下奥陶统恰干布拉克组火山岩地球化学特征及构造意义

Geochemical Features of Lower—Middle Ordovician Volcanic Rocks of Qiaganbulake Formation in the South Koumenzi Area,Xinjiang,and Its Tectonic Significances

新疆哈尔里克山口门子南地区中—下奥陶统恰干布拉克组主要发育一套海相中-基性火山岩建造,对该组中玄武岩进行岩石学、地球化学研究,结果表明恰干布拉克组玄武岩属钙碱性系列岩石,轻稀土元素较重稀土元素更富集（LREE/HREE=1.48~2.28）,无明显Eu负异常（δEu=0.91~1.02）,大离子亲石元素（Ba,Sr等）较富集,高场强元素（Nb,Ta）相对亏损,富Al高Ti。岩石地球化学特征表明早—中奥陶世恰干布拉克组玄武岩形成于火山岛弧环境。结合区域地质资料及前人研究成果,认为该区玄武岩的形成与康古尔洋盆由南向北的俯冲作用有关。

Qiaganbulake formation mainly development with a set of marine-facies basalts-andesites volcanic formation in the South of Koumenzi area,Xinjiang.Geochemical and petrographic analyses were used to the Qiaganbulake formation basalt.Study show that the basalt belongs to cal-alkaline series, which are richer in LILE than depletion of HREE and HFSE, and there is no negative Eu anomalies（Eu=0.91~1.02）. However there are large ions lithophile elements,high magnetic field elements relative loss and enrichment in Al, Ti in this area, where it illustrates performance for the volcanic arc environment. According to former scholar and some geological materials,the author supposes that the evolution of the Ordovician volcano activity may be associated with the Kanggurtag basin.