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利用电子探针和激光探针剥蚀系统(LA-ICP-MS)对北羌塘新第三纪高钾钙碱岩系英安岩中角闪石的主元素和微量、稀土元素进行了分析。结果表明,本区角闪石均属钙质角闪石亚类,主元素特征指示该套火山岩为陆壳局部熔融岩浆系列。角闪石强烈富集Sc、Ti、V、Cr、Co、Ni等弱不相容亲铁元素,而相对亏损Th、U、Pb、Rb等强不相容的大离子亲石元素。稀土元素丰度高,且无Eu异常,指示北羌塘这套高钾钙碱岩系火山岩可能是青藏高原加厚的相当于榴辉岩相物质组成的下部陆壳脱水熔融的产物。
The main elements, trace elements and rare earth elements of amphiboles from the Neogene high-kalcalite series dacite in the northern Qiangtang were analyzed by electron probe and laser probe denudation system (LA-ICP-MS). The results show that all the amphiboles in this area belong to the class of calcareous amphiboles, and the main elements indicate that the volcanic rocks are continental melt series. Amphibole is strongly enriched in Sc, Ti, V, Cr, Co, Ni and other weak incompatible pro-iron elements, while the relative loss of Th, U, Pb, Rb strong incompatible ion-lithophile elements. The high abundance of rare earth elements and the absence of Eu anomalies indicate that the northern Qiangtang high-kalcalitic rock volcanic rocks may be the thickened products of the lower continental crust dewatering and melting equivalent to the eclogite facies in the Qinghai-Tibet Plateau.