蛇纹岩氢、氧同位素组成特征及其影响因素  

Hydrogen and oxygen isotopic compositions of serpentinite and their influencing factors

作　　者：佟宏鹏 谭文汐 张葚 陈多福[1,2] TONG Hong-peng;TAN Wen-xi;ZHANG Shen;CHEN Duo-fu(College of Oceanography and Ecological Science/Center for Extreme Marine Process and Resource Research,Shanghai Ocean University,Shanghai 201306,China;Shanghai Frontier Scientific Research Base of Hadal Biosphere,Shanghai 201306,China)

机构地区：[1]上海海洋大学海洋科学与生态环境学院/极端海洋过程与资源研究中心,上海201306 [2]上海市深渊生物圈前沿科学研究基地,上海201306

出　　处：《矿物岩石地球化学通报》2024年第6期1304-1314,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41776080,41776050)。

摘　　要：蛇纹岩氢、氧同位素是示踪蛇纹石化过程的重要手段,但对不同类型蛇纹岩同位素特征及其影响因素缺乏对比研究。本文探讨了洋中脊和汇聚板块边缘泥火山蛇纹岩及俯冲型造山带蛇绿岩的氢、氧同位素特征及其影响因素。结果表明,洋中脊(δD为–86‰~–30‰,δ^(18)O为1.6‰~11.2‰)和汇聚板块边缘蛇纹岩(δD为–84‰~–29.5‰,δ^(18)O为5.8‰~10.8‰)显示了类似的氢同位素分布范围,而后者的氧同位素数据点主要集中在略重的区域,可能是因为二者蛇纹石化均以海水源流体为主,且后者数据主要来自富集18O的板片衍生流体导致的蛇纹岩泥火山样品。俯冲型造山带蛇绿岩具有最大的氢、氧同位素组成范围(δD为–133‰~–48‰,δ^(18)O为–3.2‰~13.9‰),指示其具有复杂的蛇纹石化水来源以及受大气水同位素再平衡的影响。The stable hydrogen and oxygen isotopes of serpentines serve as important tracers in the serpentinization process.However,comparative studies on the isotopic characteristics of different types of serpentinites and their influencing factors are lacking.This paper discusses the hydrogen and oxygen isotopic features and their influencing factors in serpentinites from midocean ridges,convergent plate boundary mud volcanoes,and subduction-zone ophiolites.The results show that serpentinites from the mid-ocean ridges(δD=–86‰~–30‰,δ^(18)O=1.6‰~11.2‰)and from the convergent plate boundaries(δD=–84‰~–29.5‰,δ^(18)O=5.8‰~10.8‰)both exhibit a similar range in hydrogen isotope distribution.However,the latter′s oxygen isotopic data points are mainly concentrated in a slightly heavier region.This could be due to the serpentinization in both geologic backgrounds mainly caused by seawater-derived fluids,with the latter′s data primarily from mud volcano samples enriched in 18O because of slabderived fluids.Serpentinites from the subduction-zone ophiolites have the widest range in hydrogen and oxygen isotopes(δD=–133‰~–48‰,δ^(18)O=–3.2‰~13.9‰),indicating a complex origin of the serpentinization fluids and the impact of atmospheric water isotope re-equilibration.

关 键 词：蛇纹岩 氢同位素 氧同位素 蛇纹石化水 同位素再平衡 

分 类 号：P588.323[天文地球—岩石学]