摘要
折多山花岗岩作为鲜水河断裂带活动的同构造花岗岩为藏东地区高原隆升和构造演化提供了重要信息。区域地质调查填图表明,折多山岩体的岩石组合特征为:花岗闪长岩→粗粒似斑状二长花岗岩→中粒二长花岗岩→细粒二长花岗岩。其地球化学特征表明岩石属钾玄岩-高钾钙碱质岩石,稀土配分曲线显示其轻稀土富集,重稀土亏损,具有壳源岩浆特征,稀土-微量元素投点判别图表明花岗岩形成于造山后同构造环境。根据岩石学、地球化学研究,结合鲜水河断裂活动特征分析,认为折多山花岗岩不是断裂活动形成的地壳重熔的产物,而是断裂活动引起的下地壳流体上涌形成的。该项研究支持藏东地区下地壳流体存在的假说,并表明下地壳流体的向东迁移可能是造成鲜水河断裂分期活动和藏东地区逐步隆升的最主要的原因。
The Zheduoshan Granite pluton in Kangding is a syntectonic granite pluton in the Xianshuihe active fracture zone.It provides important information for uplift and tectonic evolution of the Qinghai-Tibet Plateau.The regional geological survey indicates that the pluton consists of granodiorite,coarse porphyroid adamellite,medium-grained adamellite and fine-grained adamellite.The petrogeochemical characteristics indicate its shaoshaonite-K-rich calco-alkaline in character with enrichment in LREE and depletion in HREE characteristic of crust-derived magmatic rock which was formed in postorogenic syntectonic setting.The study shows that the pluton resulted from ascending fluids due to faulting other than crust remelting.The Xianshuihe faulting and gradual uplift of the east Tibet Plateau were attributed to the eastwards shift of the lower crust-derived fluids.
出处
《四川地质学报》
2009年第S2期58-64,共7页
Acta Geologica Sichuan
关键词
折多山
花岗岩
鲜水河断裂
地球化学特征
Zheduoshan
granite
Xianshuihe fault
geochemical characteristic
