青藏高原羌塘东部治多县左支——失多莫卜辉长岩带地球化学特征及构造意义

青藏高原羌塘东部治多县左支——失多莫卜辉长岩带形成于晚二叠世，由单一辉长岩组成。岩石富碱，Na2O〉K2O为钙碱性系列。微量元素特征表现为大离子亲石元素（LILE）富集，高场强元素分异，显示板内玄武岩特征。轻稀土元素高度富集，δEu不显亏损，为弱负异常到正异常。（87Sr／85Sr）i较低，变化于0．70419～0．70471之间，εNd（t）值较高，变化于4．3～4．9之间，显示了略亏损的地幔源区特征。该辉长岩带应形成于板内伸展扩张构造环境。

Geochemical characteristics and tectonic significance of gabbros from Zuozhi-Shiduomobu area of Zhiduo County of eastern Qiangtang in the Qinghai-Tibet Plateau

Located in Zhiduo County, eastern Qiangtang, Qinghai-Tibet Plateau, and formed in the Late Permian, the Zuozhi-Shiduomobu gabbros belt is consisted simply of gabbros. The gabbros are rich in alkaline with Na2O high than K2O, being the rocks of calc-alkaline series. Their trace elements are characterized by enrichment of large-ion-lithophile elements （LILE） and fractionation of high-field-strength elements （HFSE）, displaying typical characteristics of within-plate basalts. Light rare earth elements are significantly enriched with δEu values varying from slightly negative to positive. （87Sr/86Sr）iratios are relatively low, ranging from 0. 70419 to 0. 70471; εNd（t） values are relatively high, ranging from 4.3 to 4.9, showing that the gabbros are derived from a slightly depleted mantle source. It is believed that the gabbros from the Zuozhi-Shiduomobu area are formed in a within-plate extensive tectonic environment.