青藏高原北羌塘新生代高钾钙碱岩系火山岩角闪石类型有痕量元素地球化学
Trace element geochemistry and classification of amphiboles of the Cenozoic high-potassium calc-alkaline volcanic rock series from north Qiangtang, Qinghai-Tibetan plateau.
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摘要: 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、角闪石强烈富集Sc、Ti、V、Cr、Co、Ni等不相容亲铁元素，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，批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。Abstract: Based on the electron microprobe and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) analyses, the major and trace element features of amphibole from the Cenozoic high-potassium calc-alkaline dacite of north Qiangtang are discussed in this paper. The result indicates that all of the amphiboles belong to calcic series. Their major elements imply that the dacite should be of crustal origin. And the amphiboles show the Sc, Ti, V, Cr, Co, Ni enrichment and the Th, U, Pb, Rb depletion. Especially, the amphiboles exhibit high content in rare earth element but no remarkable Eu depletion. It may imply that the Cenozoic high-potassium calc-alkaline volcanic rocks from north Qiangtang might be originated from the thickened eclogitic deep crust of Tibetan plateau by dehydration partial melting.
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Key words:
- Amphibole /
- Major and trace element /
- Geochemistry /
- North Qiangtang /
- Qinghai-Tibetan plateau
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