辽宁宽甸地区上地幔岩石圈组成及热结构——来自地幔岩包体的信息  

The Composition and Thermal Structure of the Upper Mantle Lithosphere Beneath Kuandian Area,Liaoning Province——Implications from Mantle Xenoliths

作　　者：方同辉[1] 马鸿文[2] 

机构地区：[1]北京矿产地质研究所,100012 [2]中国地质大学材料科学与工程学院,北京100083

出　　处：《地质论评》1999年第S1期450-457,共8页Geological Review

基　　金：国家教委"跨世纪优秀人才计划"基金资助项目的部分成果

摘　　要：中更新世时期火山爆发形成的宽甸黄椅山碱性玄武岩中含有种类丰富的地幔岩包体,为研究该地区的上地幔组成及热结构提供了良好的条件。本文计算了地幔岩包体的平衡温压、岩石密度及弹性波速值。结果表明:该地区莫霍面埋深为35～38km。38～65km范围内普遍存在着尖晶石二辉橄榄岩,54～64km为尖晶石辉石岩转变为石榴子石辉石岩的过渡带,石榴子石二辉岩分布范围为54～75km,推测75 km以下进入上地幔低速层。45～80 km范围内的热结构可表示为:t(℃)=847.17+1.557d+0.02235d^2。A variety of mantle xenoliths were entrapped in alkalic basalts in Huangyishan, Kiandian area,Liaoning Province, resulting from volcanic eruption during the middle Pleistocene. These mantle xenoliths are helpful to understand the composition and thermal structure of the upper mantle lithosphere beneath the Kuandian area, the equilibrium temperature—pressure, bulk density and seismic velocity of mantle xenoliths are estimated in this paper. The results show that the depth of Moho is ca. 35 km to 38 km, spinel lherzolites prevail in the range from 38 km to 65 km, transition zone from spinel pyroxenites to garnet pyroxenites lies between 54 km and 64 km, and garnet websterites distribute in a depth from 54 km to 75 km. It is supposed that the low-velocity layer in the upper mantle is below 75 km. the thermal state of the upper mantle within depths of 45 km to 80 km beneath Kuandian area may be formulated as:t(℃) = 847.17 + 1.557d+0. 02235d^2.

关 键 词：地幔岩包体 上地幔岩石圈 热结构 宽甸 

分 类 号：P542.5[天文地球—构造地质学]