| 超高压变质作用过程中的流体——来自苏鲁超高压变质岩岩石学、氧同位素和流体包裹体研究的限定 |
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| 引用本文： | 张泽明,沈昆,赵旭东,石超.超高压变质作用过程中的流体——来自苏鲁超高压变质岩岩石学、氧同位素和流体包裹体研究的限定[J].岩石学报,2006,22(7):1985-1998. |
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| 作者姓名： | 张泽明 沈昆 赵旭东 石超 |
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| 作者单位： | 1. 中国地质科学院地质研究所,北京,100037
2. 山东省地质科学研究院,济南,250013 |
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| 基金项目： | 国家自然科学基金;国家重点基础研究发展计划(973计划) |
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| 摘 要： | 苏鲁造山带超高压变质岩岩石学、氧同位素、流体包裹体和名义上无水矿物的研究表明，流体-岩石相互作用在大陆地壳的俯冲与折返过程中起到多重的重要作用，并形成了复杂的流体演化过程：（1）大陆表壳岩通过与高纬度大气降水的交换作用被广泛水化，并获得了异常低的氧同位素成分；（2）在水化陆壳物质的俯冲过程中发生了一系列的进变质脱水反应，所释放的流体主要结合进了高压、超高压含水矿物和名义上无水超高压矿物；（3）在超高压变质过程中，以水为主的变质流体通过选择性的吸收使其盐度逐渐升高，并在峰期出现高密度、高盐度的H2O或CO2-H2O流体。有机质的分解反应在局部形成了以CO2、N2、CH4或它们的混合物为主要成分的变质流体；（4）名义上无水超高压矿物的结构水出溶是早期退变质流体的主要来源，并在局部富集形成了高压变质脉体；（5）透入性的中、低盐度水流体活动使超高压变质岩通过一系列的水化反应转变成角闪岩相变质岩；（6）沿韧性剪切带和脆性破碎带的强烈水流体活动为绿片岩相退变质作用和低压石英脉的形成提供了变质流体；（7）可变盐度的H2O或CO2-H2O流体是整个超高压变质岩形成与折返过程中的主要流体，但局部的流体．岩石相互作用形成了非极性的变质流体。
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| 关 键 词： | 大陆深俯冲 超高压变质 流体-岩石相互作用 |
| 文章编号： | 1000-0569/2006/022(07)-1985-98 |
| 收稿时间： | 04 10 2006 12:00AM |
| 修稿时间： | 06 18 2006 12:00AM |
Fluid during the UHP metamorphism: constraints from the petrology, oxygen isotope and fluid inclusion studies of the Sulu UHP metamorphic rocks. |
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| ZHANG ZeMing,SHEN Kun,ZHAO XuDong,SHI Chao.Fluid during the UHP metamorphism: constraints from the petrology, oxygen isotope and fluid inclusion studies of the Sulu UHP metamorphic rocks.[J].Acta Petrologica Sinica,2006,22(7):1985-1998. |
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| Authors: | ZHANG ZeMing SHEN Kun ZHAO XuDong SHI Chao |
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| Institution: | 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; 2. Geological Institute of Shandong Province, Jinan 250013, China |
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| Abstract: | Based on the comprehensive investigations of the petrology, oxygen isotope, fluid inclusion and nominally anhydrous minerals (NAMs) of the ultrahigh-pressure (UHP) metamorphic rocks from the Sulu orogenic belt it has been shown that fluids have played important and multiple roles and experienced complicated evolution processes by fluid-rock interactions during the subduction and exhumation of the continental crust. The features are as follows. (1) The supracrustal materials were extensively hydrated by the interaction with cold meteoric water with extremely low oxygen isotopic compositions. (2) A series of dehydration reactions took place during subduction of the hydrated continental crust; the released fluids mainly entered into volatile-bearing HP and UHP minerals, such as glaucophane, phengite and epidote, apatite, and into nominally anhydrous minerals, such as garnet, omphacite, rutile and coesite. (3) The salinity of the fluids increased by selective reactions with UHP metamorphic minerals; consequently high-salinity and high density aqueous fluids were produced at the peak-UHP metamorphism. In addition, fluids of CO2, N2, CH4 or their mixtures occurred locally that are probably related with decomposition of organic substances. (4) Fluids exsolved from the NAMs are the main source for the HP hydrations of retrogression and for the forming of local HP veins during the early stage of uplift of UHP rocks. (5) Extensive amphibolite-facies retrograde metamorphism of UHP rocks took place by pervasive activities of low-salinity aqueous fluids. (6) The greenschist-facies overprinting and low-pressure quartz veins were produced by low-temperature fluid-rock interactions along the ductile-shear zones and brittle faults during the late stage of uplift of UHP rocks. (7) H2O and/or CO2-HO2 fluids with variable salinity were dominated during the subduction and exhumation of the continental crust. |
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| Keywords: | Continental deep subduction UHP metamorphism Fluid-rock interactions |
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