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藏东贡觉盆地古近纪火山岩形成于印度-欧亚板块碰撞造山后的伸展环境中,火山活动受水平剪切-走滑断裂带控制。火山岩以高Si O2、Al2O3、K2O、Na2O和低MgO、Ti O2为特征,属高钾钙碱性中酸性火山岩。火山岩中富集大离子亲石元素(LILE)、轻稀土元素(LREE),亏损高场强元素(HFSE)和一部分相容元素(Co、Ni、V、Sc);无Eu异常但有弱的Ce负异常。火山岩源区可能是经历了壳源混合作用的富集交代地幔。富集组分来自壳源,它们沿古俯冲带以再循环方式进入地幔楔,并与地幔发生交代作用。
The Paleogene volcanic rocks in the eastern Tibetan Colony of Jogjakarta formed during the extension of the Indian-Eurasian plate collision orogeny, and the volcanic activity was controlled by the horizontal shear-strike-slip fault zone. Volcanic rocks with high Si O2, Al2O3, K2O, Na2O and low MgO, Ti O2 is characterized by high-K calc-alkaline acidic volcanic rocks. LILE, LREE, HFSE and some compatible elements (Co, Ni, V, Sc) are enriched in volcanic rocks. There is no anomalous Eu but weak Ce negative anomaly. Volcanic source areas may be enrichment metasomatism experienced by the crust source mixing. Enriched components originate from the crust, which recycle into the mantle wedge along the ancient subduction zone and interact with the mantle.