地质通报Issue(6)：820-829,10.
南帕米尔北缘切实界别辉长岩LA-ICP-MS锆石U-Pb定年、地球化学特征及其地质意义
LA-ICP-MS zircon U-Pb dating, geochemis-try and tectonic implications of the Qieshijiebie gabbro on the northern margin of South Pamir
摘要
Abstract
Mafic intrusions are distributed widely on the northern margin of South Pamir and intruded into the Early Permian stra-ta. The LA-ICP-MS zircon U-Pb dating of the Qieshijiebie gabbro yielded an age of 269.5±1.3Ma, revealing that the mid-Perm-ian mafic magmatic activity existed in this area. The intrusions belong to alkaline rock series, and their SiO 2 values are 46.68%~49.20%, TiO2 value is 1.40% on average, and K2O+Na2O=3.94%~5.83%. The REE patterns of the samples exhibit enrichment of LREE, with δEu equal to 0.92~1.31, and have no obvious Eu anomalies. The characteristics of trace elements are similar to those of intraplate basalts, showing relative enrichment of LILE such as K, Rb, Sr and Ba and depletion of HFSE (Nb, Ta, Ti, P) and Th, U. The trace element identification diagrams also show that they were developed in an intraplate setting, suggesting that South Pamir and South Qiangtang were both in a tectonic environment of intraplate extension, whereas the Gangdise belt was in an is-land-arc setting during Permian, as shown by the comparison of the Qieshijiebie gabbro with the mafic volcanics in adjacent re-gions. The conclusion reached by the authors provides a basis of magmatism for dividing Carboniferous-Permian tectonic units in Pamir and Tibetan Plateau.关键词
辉长岩/LA-ICP-MS锆石U-Pb年龄/板内伸展环境/南帕米尔Key words
gabbro/LA-ICP-MS zircon U-Pb dating/intraplate extension setting/South Pamir分类
天文与地球科学引用本文复制引用
洪俊,计文化,张辉善,姚文光,孟广路,王斌,吕鹏瑞,杨博..南帕米尔北缘切实界别辉长岩LA-ICP-MS锆石U-Pb定年、地球化学特征及其地质意义[J].地质通报,2014,(6):820-829,10.基金项目
中国地质调查局项目 （）
