P-T-deformation paths of regional metamorphic belts at convergent plate boundaries

汇聚板块边界区域变质带的P-T变形路径

• 批准号: 15340167
• 负责人: IWAMORI Hikaru
• 金额: $ 7.87万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15340167/
• 关键词: plate boundary; subduction zone; regional metamorphic belt; deformation; thermal field; water cycling; magmatism; 褶曲; 有限要素法; 沈み込み帯; マグマ; 前弧ウエッジ; 変成作用; 変形作用; 3次元変形; 3次元コーナー流れ; 一軸伸張

This project aims at (1)constructing a numerical model for predicting 3-D deformation of metamorphic belts intercalated between the plates, as well as thermal structures, for variable driving forces from plate motions and deformations, (2)constructing a numerical model for predicting material cycling (in particular water) under perturbed situations associated with ridge subduction, which is thought to be critical for metamorphism and magmatism, (3)comparing the model results and the P-T and deformation history recorded in metamorphic and igneous rocks, in order to obtain a perspective view. According to (1) to (3), we obtain the following results : (A)Among the possible deformation fields (3-D collision, obduction, corner flow and/or squeezing flow in the forearc wedge, and combination of these flows), plain strain or oblate strain is dominant, whereas prolate strain, that is observed in the Cretaceous regional metamorphic belts of the Japan arcs (Ryoke and Sambagawa belts), Franciscan belt in the western United States, is reproduced only in the 3-D corner flow, (B)the Cretaceous regional metamorphic belts of the Japan arcs is deduced to have been produced by 3-D corner flow in the forearc wedge, associated with ridge subduction in Cretaceous, which had supplied both heat and water to the forearc wedge to heat up and soften the region, (C)considering the phase relationships of the hydrous basaltic and peridotitic rocks, the water cycling is thought to be limited to a shallow part (<50 km depth), without significantly carrying water to the deeper part, when the ridge subduction occurs, (D)the water cycling associated with subduction of plates with an average age is also limited to relatively shallow part (<200 km depth) due to dehydration of the major hydrous mineral phases, whereas nominally anhydrous minerals (such as olivine) bring a small amount of water to the deeper mantle.

该项目旨在 (1) 构建一个数值模型来预测插在板块之间的变质带以及热结构的 3-D 变形，以预测板块运动和变形产生的可变驱动力，(2) 构建一个数值模型来预测板块运动和变形带来的可变驱动力与山脊俯冲相关的扰动情况下的物质循环（特别是水），这被认为对于变质作用和岩浆作用至关重要，（3）比较模型结果和记录的 P-T 和变形历史在变质岩和火成岩中，以获得透视图。根据(1)至(3)，我们得到以下结果： (A)可能的变形场（3-D碰撞、仰冲、前弧楔中的角流和/或挤压流，以及这些流的组合） ，平原应变或扁圆应变占主导地位，而在日本弧的白垩纪区域变质带（Ryoke和Sambakawa带）以及美国西部的方济各带中观察到的长长应变被再现仅在 3-D 角流中，(B)日本岛弧的白垩纪区域变质带被推断是由弧前楔中的 3-D 角流产生的，与白垩纪山脊俯冲有关，提供了热量和水到弧前楔以加热和软化该区域，(C)考虑到含水玄武岩和橄榄岩的相关系，水循环被认为是有限的当洋脊俯冲发生时，向较浅的部分（<50 km深度）转移，而没有显着地将水输送到较深的部分，（D）与平均年龄板块俯冲相关的水循环也仅限于相对较浅的部分（< 200公里深度）由于主要含水矿物相的脱水，而名义上无水矿物（例如橄榄石）将少量水带到更深的地幔中。

项目成果

Principal and independent component analyses of chemical compositional data

化学成分数据的主成分和独立成分分析

• 发表时间: 2005
• 期刊: Monthly Earth 51
• 作者: H.Iwamori;S.Horiuchi;H.Iwamori
• 通讯作者: H.Iwamori

Okamoto, A., Toriumi, M.: "Optimal mixing properties of calcic and subcalcic amphibole : application of Gibbs' method to the Sanbagawa schists, SW Japan"Contrib.Mineral.Petrol.. 146. 529-545 (2004)

Okamoto, A., Toriumi, M.：“钙质和亚钙质角闪石的最佳混合特性：吉布斯方法在日本西南部三波川片岩中的应用”Contrib.Mineral.Petrol.. 146. 529-545 (2004)

Thermal structure, water cycling and magmatism in subduction zones

俯冲带的热结构、水循环和岩浆作用

• 发表时间: 2003
• 期刊: Earthquake mechanism and water (University of Tokyo Press, Tokyo)
• 作者: John B.Swenson;Tetsuji Muto;H.Iwamori;H.Iwamori
• 通讯作者: H.Iwamori

化学組成データと主成分・独立成分分析

化学成分数据和主成分/独立成分分析

• 发表时间: 2005
• 期刊: 月刊地球 51
• 作者: P. Tekasalcull;M. Furuuchi;S. Tekasakul;J. Chomanee;Y. Otani;岩森 光
• 通讯作者: 岩森 光

Iwamori, H.: "Transportation of water in subduction zones"Geochim Cosmochim Acta. 67. A181-A181 (2003)

Iwamori, H.：“俯冲带中的水输送”Geochim Cosmochim Acta。