西藏白朗县南闪长岩地球化学、同位素年代学特征及其构造意义

摘要

通过对西藏白朗县南地区新发现的中性侵入体岩石学、岩石地球化学、同位素年代学特征的研究，认为其属钙碱性岩系列，具轻稀土元素富集，重稀土元素亏损的特征，岩石地球化学特征具有板内玄武岩特征，为喜马拉雅被动陆缘伸张-挤压阶段的中基性岩，侵入体形成时代为晚三叠世。以上研究为雅鲁藏布江新特提斯洋早期被动陆缘沉积盆地演化历程提供了岩浆岩方面的新证据。%In this paper, petrology, geochemical characteristics and U-Pb isotope chronology were comprehensively investigated to analyze the geological features of the intermediate intrusive rocks discovered in the south of Bailang County, Tibet. The results show that these rocks belong to calc-alkaline rock series, with LREE enrichment and HREE depletion;they have geochemical characteris⁃tics of intraplate basalts, being mafic intrusive body formed at the Himalayan passive continental margin stretching-compression stage in the late Triassic period. The results obtained by the authors provide new magmatic evidence for Early Tethys passive margin sedi⁃mentary basin evolution of the Yarlung Zangbo River.