The origin and role of fluid associated with lower crustal metamorphism

下地壳变质作用流体的起源和作用

• 批准号: 20340148
• 负责人: TSUNOGAE Toshiaki
• 金额: $ 9.4万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2008
• 资助国家: 日本
• 起止时间: 2008 至 2011
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-20340148/
• 关键词: ゴンドワナ; グラニュライト; 流体包有物; 超高温変成作用; 大陸地殻; 造山帯; グラニュライド

Fluid in lower crust probably plays an important role on the stability of mineral assemblages in various metamorphic and igneous rocks at high pressure and temperature. Although it is generally known that CO_2 is an abundant fluid component in middle to lower crust, while H_2O is dominant in shallower level, the origin of the fluid and its role during P-T evolution of crustal rocks are not known. In this study we therefore focused on fluid inclusions in granulite to amphibolite facies rocks, identified fluid specimens, and attempted to unravel the role of fluid during high-grade metamorphism. All the analyzed rocks contain CO_2 trapped in various minerals such as garnet and quartz, which confirms thatCO_2 is the dominant fluid in the lower crust. Carbon isotope study on some inclusions suggest that some CO_2 were derived from mantle. H2O bearing fluids were also identified, but they are mostly trapped in a retrograde stage. Phase equilibrium modeling of mineral assemblages on orthogniess from southern India suggest that infiltration of H_2O-bearing reduced fluid (probably H_2O + CH_4) during a retrograde (around 700℃) formed orthopyroxene-bearing granulite-facies assemblages, which indicates oxidation state, as well as H_2O activity, of fluid probably controls mineral paragenesis during high-grade metamorphism in lower crust.

下地壳流体可能对高压高温下各种变质岩和火成岩中矿物组合的稳定性起着重要作用，尽管众所周知，中下地壳中CO_2是丰富的流体成分，而H_2O在中下地壳中占主导地位。在较浅的层面上，流体的起源及其在地壳岩石的 P-T 演化过程中的作用尚不清楚，因此在这项研究中，我们重点关注麻粒岩到角闪岩相岩石中的流体包裹体，识别了流体样本，并试图揭示流体在高级变质作用过程中的作用，所有分析的岩石都含有石榴石和石英等各种矿物中捕获的CO_2，这证实了CO_2是下地壳中一些包裹体的主要流体。还发现了一些来自地幔的CO_2，但它们大多被困在印度南部矿物组合的逆行阶段。表明逆行（700℃左右）过程中含H_2O还原流体（可能是H_2O+CH_4）的渗透形成含斜方辉石麻粒岩相组合，这表明流体的氧化态以及H_2O活性可能控制着逆行过程中的矿物共生。下地壳的高级变质作用。

项目成果

Fluids in high- to ultrahigh-temperature metamorphism along collisional sutures: Record from fluid inclusions

• DOI: 10.1016/j.jseaes.2010.11.016
• 发表时间: 2011-08
• 期刊: Journal of Asian Earth Sciences
• 影响因子: 3
• 作者: T. Tsunogae;M. Santosh

高圧-超高温グラニュライトに含まれる珪線石集合結晶からみた南インド・ゴンドワナ縫合帯の温度圧力経路

从高压和超高温麻粒岩中硅线石聚集晶体看到的南印度冈瓦纳缝合带的温度-压力路径

• 发表时间: 2009
• 作者: 清水恒子;角替敏昭;M.Santosh
• 通讯作者: M.Santosh

レーザーアブレーションICP質量分析装置を用いたインド南部Achankovil Shear Zone産グラニュライトのジルコンU-Pb年代測定

使用激光烧蚀 ICP 质谱法对印度南部阿尚科维尔剪切带的麻粒岩进行锆石 U-Pb 定年

• 发表时间: 2008
• 作者: 佐藤桂;M. Santosh;角替敏昭;昆慶明;山本伸次;平田岳史
• 通讯作者: 平田岳史

T.Evidence for high-pressure metamorphism in a collisional orogen in Gondwana suture: High P-T phase relation of Mg-staurolite in FMASH system under high fO2 conditions

T. 冈瓦纳缝合带碰撞造山带高压变质作用的证据：高 fO2 条件下 FMASH 系统中镁十字石的高 P-T 相关系

• 发表时间: 2008
• 作者: Sato;K.;Santosh;M.;Tsunogae;T.
• 通讯作者: T.

超高温変成岩に含まれるCO_2およびCO_2+H_2O包有物の産状からみた流体の起源:東南極ナピア岩体の例

从超高温变质岩中CO_2和CO_2+H_2O包裹体的赋存看流体来源——以东南极洲纳皮尔岩体为例

• 发表时间: 2009
• 作者: 角替敏昭;M.Santosh
• 通讯作者: M.Santosh