摘要
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。
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.
出处
《资源调查与环境》
2009年第3期164-173,共10页
Resources Survey & Environment