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西藏西南部达巴-休古嘎布蛇绿岩带中地幔橄榄岩的成因
引用本文:徐德明, 黄圭成, 黄陵勤, 雷义均, 李丽娟. 西藏西南部达巴-休古嘎布蛇绿岩带中地幔橄榄岩的成因[J]. 华南地质, 2006, (3): 10-18. doi: 10.3969/j.issn.1007-3701.2006.03.002
作者姓名:徐德明  黄圭成  黄陵勤  雷义均  李丽娟
作者单位:宜昌地质矿产研究所,湖北,宜昌,443003;; 宜昌地质矿产研究所,湖北,宜昌,443003;; 湖南省地质矿产勘查局四一六队,湖南,株州,412003;; 宜昌地质矿产研究所,湖北,宜昌,443003;; 宜昌地质矿产研究所,湖北,宜昌,443003
基金项目:中国地质调查局资助项目
摘    要:本文报道了西藏西南部达巴-休古嘎布蛇绿岩带中橄榄岩的矿物化学资料.橄榄岩中主要造岩矿物化学成分的分析研究表明,该区橄榄岩为残余地幔成因,但它们不是地幔简单熔化的残余物.尖晶石中Cr#及辉石中Ti的广泛变化表明它们具有复杂的熔融历史及地幔交代作用的印记,其形成过程可能经历了两种构造环境的转变.早期在MORB环境下形成低Cr#(尖晶石)橄榄岩;其后由于洋内俯冲作用,早先形成的低熔橄榄岩被消减到岛弧之下再度发生熔融形成高Cr#(尖晶石)橄榄岩.从而,在古大洋消失之后形成的碰撞带上同时保存了MORB型和SSZ型两类蛇绿岩.

关 键 词:地幔橄榄岩   矿物化学   地幔熔融   地幔交代   达巴-休古嘎布蛇绿岩带
文章编号:1007-3701(2006)03-0010-09
收稿时间:2005-04-26
修稿时间:2005-04-26

The Origin of Mantle Peridotites in the Daba-Xiugugabu Ophiolite Belt,SW Tibet
XU De-ming, HUANG Gui-cheng, HUANG Lin-qin, LEI Yi-jun, LI Li-juan. The Origin of Mantle Peridotites in the Daba-Xiugugabu Ophiolite Belt,SW Tibet[J]. South China Geology, 2006, (3): 10-18. doi: 10.3969/j.issn.1007-3701.2006.03.002
Authors:XU De-ming  HUANG Gui-cheng  HUANG Lin-qin  LEI Yi-jun  LI Li-juan
Abstract:This paper reports the mineral chemical data of mantle peridotites in the Daba-Xiugugabu ophiolite Belt, SW Tibet. In the relationship between Cr^# of spinel and Fo of olivine, the peridotites fall within the OSMA and it indicate they are the residual mantle peridotite, but not residue of a simple partial melting. The variations of Cr^# in spinel and Ti in pyroxene suggest that the Daba-Xiugugabu peridotite had a history of complex melting and an impress of mantle metasomatism. The processes of formation of the peridorites possibly include a transition from a tectonic setting to another. The lower Cr^# of spinel in peridotite can be explained by partial melting and MORB extraction in mid-ocean stage. Subsequently, the peridotites with low melting degree were subducted beneath the arc area and re-melted, and peridotites with higher Cr^# of spinel formed. Therefore, two of MORB-type and SSZ-type ophiolite crop out along collision belt formed after the closing of the old ocean.
Keywords:mantle peridotites   mineral chemistry   mantle melting   mantle metasomatism   Daba-Xiugugabu ophiolite belt
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