内蒙古贺根山蛇绿岩岩石成因和地壳增生的地球化学制约  

Geochemical Constraints on Petrogenesis and CrustalAccretion of the Hegenshan Ophiolite,Northern China

作　　者：白文吉[1] 杨经绥[1] 胡旭峰[1] 周美付[1] 

机构地区：[1]中国地质科学院地质研究所

出　　处：《岩石学报》1995年第S1期112-124,共13页Acta Petrologica Sinica

基　　金：中国自然科学基金;加拿大NSEC基金

摘　　要：内蒙古贺根山蛇绿岩代表了吉亚洲洋岩石圈的最后残余。由贺根山、朝根山、乌斯尼黑和崇根山等岩块组成。岩石类型有地幔橄榄岩、橄长岩和辉长岩组成的堆晶岩、玄武质熔岩以及切割堆晶岩的玄武质和辉石岩质岩墙。方辉辉橄岩具有稍高的Ｔｉ含量和台高铝尖晶石，并且含有耐火型豆荚状铬铁矿，与橄长岩为主的堆晶岩序列共生。大部分岩墙强烈亏损某些不相容元素，与未成熟岛弧岩石相似。玄武质熔岩来源于独立的岩浆，具有较宽的化学成分变化特点，表明它们可能形成于岛弧一边缘盆地体系中．The Hegenshan ophiolite in inner Mongolia of China represents.the latest remnants of the PaleoAsian oceanic lithosphere. This ophiolite suite includes four major ophiolite massifs: Hegenshan, Caogenshan,Wusnihei and Chongenshan massifs. The lithologic units of the ophiolite are mantle peridotites. cumulatesequences of troctolite and gabbros, basalatic lavas and basaltic and pyroxenitic dykes which cut the cumulates.While the cumulate troctolites and gabbros are relatively fresh, the lavas and peridotites are stronglytransformed. The mantle harzburgites are the depleted residue efter partial melting. However, they havesomewhat high-Ti contents and high-Al chromite and contain refractory podiform chromitites, coupled withtroctolite-dominant cumulate sections, all compatible to the MORB ophiolite. Most of the dykes are stronglydepleted in some incompatible elements and are aimilar to some rocks from immature island arcs. The volcaniclavas from the Hegenshan ophiolite have ben derived from separated magmas. The wide chemical variations ofthe Hegenshan lavas cannot be easily explained by an ocean-ridge system. An island arc-marginal basin systemcould better account for the observed chemical features.

关 键 词：贺根山 蛇绿岩 岩石成因 地壳增生 地球化学制约 

分 类 号：P581[天文地球—岩石学]