缅甸达贡山蛇绿岩体的地球化学特征及其成矿意义  

Geochemical characteristics and metallogenic significance of ophiolite rock mass in Tagaung Taung of Myanmar

作　　者：周守余[1] 杨明德[1] 刘伟[1] 吴小雷[1] 吴继炜[1] 李发兴[1] 张志伟[2] 

机构地区：[1]中国有色桂林矿产地质研究院有限公司,广西桂林541004 [2]海南省地质调查院,海南海口570226

出　　处：《矿产与地质》2016年第3期390-397,共8页Mineral Resources and Geology

基　　金：国外矿产资源风险勘查专项资金项目(201210A02000203)资助

摘　　要：缅甸达贡山蛇绿岩体是达贡―密支那缝合带的重要组成部分,受控于板块碰撞结合带。该岩体主要由蛇纹石化橄榄岩、斜方辉石橄榄岩等组成。变质橄榄岩具有低的A12O3和CaO含量,以富Mg、贫Ti、HREE为特征,显示一种残留地幔岩的稀土元素地球化学特征,与世界上典型蛇绿岩体中方辉橄榄岩的特征值一致。经估算,达贡山蛇纹岩原岩是原始地幔经过9%~14%部分熔融的地幔残留,初步研究认为,达贡山蛇纹岩原岩是洋内俯冲初始阶段上涌软流圈地幔部分熔融的地幔残留,受类SSZ型熔体交代作用而仍然富集轻稀土元素（LREE）及U、Nb,属类SSZ型地幔橄榄岩,达贡山蛇绿岩体可能形成于俯冲带（SSZ）环境。岩体的m/f平均值8.02〉6.5,利于铬铁矿的成矿。The ophiolite rock mass in Tagaung Taung is an important part of Tagaung-Myitkyina suture zone and is controlled by the junction zone of plate collision.The rock mass mainly consists of serpentinized peridotite and orthopyroxene peridotite.Metamorphic peridotite has low contents of A12O3 and CaO and is characterized by rich Mg and poor Ti and HREE.It has REE geochemical characteristics of residual pyrolite,which is consistent with the characteristic values of harzburgite in typical ophiolite rock mass elsewhere.According to authors＇ estimation Tagaung Taung serpentinite protolith is the residue of partly（9%-14%）fused primitive mantle.Through preliminary study,it appears that Tagaung Taung serpentinite protolith is the residue of partly fused upwelling asthenosphere mantle in the initial period of intra-oceanic subduction.Tagaung Taung serpentinite protolith is subject to metasomatism of quasi-SSZ type melt and is enriched with LREEs and elements like U and Nb,and it indicates that it is quasi-SSZ type mantle peridotite.Tagaung Taung ophiolite rock mass may be formed in the environment of subduction zone（SSZ）.The average value of m/f of the rock mass is 8.02 which is above 6.5,so it is in favor of the mineralization of chromite.

关 键 词：蛇绿岩体 地球化学特征 达贡—密支那缝合带 成矿意义 达贡 缅甸 

分 类 号：P588.12[天文地球—岩石学]