塔里木盆地南北缘新生代火山岩成因及其地质意义  

CENOZOIC MAGMATISM IN THE SOUTH AND NORTH RIMS OF TARIM BASIN:PETROGENESIS AND TECTONIC IMPLICATIONS

作　　者：罗照华[1] 白志达[1] 赵志丹[1] 詹华明[1] 李莉[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083

出　　处：《地学前缘》2003年第3期179-189,共11页Earth Science Frontiers

基　　金：国家自然科学基金资助项目 (4 0 2 72 0 3 3 ) ;国家重点基础发展规划资助项目 (G19980 40 80 7 ;0 0 2CB412 60 3 )

摘　　要：塔里木盆地南北缘几个地方的新生代火山岩类具有贫硅富碱、特别是富钾的特点 ,均属于碱性火成岩系列。大部分样品SiO2 质量分数低于 5 3% ,全碱质量分数大于 3%。按照全碱 SiO2 的关系 ,它们可以划分为 3种类型 :钾质碧玄岩钾质粗面玄武岩钾质碱性橄榄玄武岩类、钾质橄榄安粗岩粗面岩类和钾质粗面玄武岩橄榄玄武粗安岩安粗岩类。岩石普遍含有橄榄石、单斜辉石、斜长石与黑云母等矿物斑晶 ,部分火山岩中见有辉石、金云母、角闪石高压巨晶 ,岩石地球化学特征与幔源捕虏体和高压巨晶的产出表明它们具有原生岩浆的性质。岩石地球化学参数的变异趋势暗示岩浆起源于深部流体强烈活动的地幔环境 ,而不是受控于分离结晶作用。岩浆活动受控于印度 -亚洲大陆碰撞构造体制派生的大型走滑体制 ,与大陆裂谷、地幔柱和陆内俯冲作用无关。Most of the Cenozoic volcanic rocks from the south and north rims of Tarim basin are classified as alkali series. They are low in silicon (SiO_2<53%), enriched in alkaline (K_2O+Na_2O>3%), especially enriched in potassium. They can be further subdivided into three types on the basis of their composition of total alkalis and SiO_2. They are potassic basanite-potassic trachybasalt-potassic alkaline Ol-basalt assemblage, potassic Ol-mugearite-trachytoid, and potassic trachybasalt-shoshonite-latite assemblage. Olivine, clinopyroxene, plagioclase and biotite are usually found as phenocrysts in the rocks. The geochemistry of volcanic rocks and the deep-seated xenoliths and megacrysts ( such as pyroxene, phlogopite and amphibolite) suggest that they have the characteristics of primitive magmas. Petrology and geochemistry show that the magma was originated from partial melting of upper mantle sources with strong activities of fluid, instead of controlling by fractional crystallization. Their origin was related to the large scale strike-slip tectonic regime derived from the collision between India and Asia. It seems that they are not tectonically related to continental rift, intra-continental subduction and mantle plume.

关 键 词：火山岩 塔里木盆地 青藏高原 流体 深部过程 天山 地球动力学 

分 类 号：P588.1[天文地球—岩石学]