岩石矿物学杂志2009，Vol.28Issue(4)：339-348,10.
羌塘西北部松西地区新生代火山岩岩石地球化学特征及成因讨论
Geochemistry and genesis of Cenozoic volcanic rocks in Songxi area, northwestern Qiangtang, Tibet
摘要
Abstract
Cenozoic volcanic rocks are distributed in Songxi area of northwestern Qiangtang within northern Tibet, a marine volcanic rock association composed of andesite, dacite and rhyolite belongs to the calc-alkaline-high K calc-alkaline series. The rocks have high large-ion lithophile elements LIL and LREE, low HFSE, and relatively depleted Nb, Ta, Ti, reflecting features of terrigenous magma. SiO2 contents of basic volcanic rocks are less than 53%, suggesting that basaltic andesite in Songxi area was not entirely produced by direct partial melting from the continental crust generation, and that the formation of basaltic andesite must have had the participation of a small amount of mantle materials. Eu negative anomalies are not obvious, implying that magma was derived from the thickening of the lower continental crust resulting from the collision and long-term squeeze between the Indian plate and the Eurasian plate, which led to the shortening and thickening of the continental crust in the northern part of Qinghai-Tibet plateau, including Qiangtang area. The northward subduction of the Lhasa block of continental lithosphere and the underplating of upwelling asthenosphere materials in the Qiangtang landmass triggered off the formation of the thickened lower crust through partial melting.关键词
松西地区/火山岩/新生代/钙碱性-高钾钙碱性Key words
Songxi area/ volcanic rocks/ Cenozoic/ calc-alkaline-high K calc-alkaline分类
天文与地球科学引用本文复制引用
钟华明,吕达,童劲松,夏军,鲁如魁..羌塘西北部松西地区新生代火山岩岩石地球化学特征及成因讨论[J].岩石矿物学杂志,2009,28(4):339-348,10.基金项目
中国地质调查局资助项目(200213000007) （200213000007）
