Deformation mechanism of rocks due to intense strain rate in shear zone

剪切带强应变率岩石变形机制

• 批准号: 16340151
• 负责人: MICHIBAYASHI Katsuyoshi
• 金额: $ 7.3万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340151/
• 关键词: EBSD; peridotite; rheology; 地震; マントルかんらん岩; 結晶方位定向性; マリアナ海溝; チャレンジャー海淵; ゼノリス; 静岡大学機器分析センター; 高温高圧変形実験; マイロナイト; 中央構造線; 目潟火山; 高音高圧変形実験

We planned to investigate ultramylonite, which is very-fine grained fault rocks in ductile shear zones, using simultaneous EDS and EBSD in order to determine the phase distribution and the dominant deformation mechanisms. The sample had been analysed previously using both EBSD and light microscopy, but resolution limitations prevented a detailed analysis of the finer grained zones. It was suspected that diffusion creep (atomic migration along grain boundaries) was the dominant mechanism in these zones-this analysis using a FEG-SEM could verify this hypothesis. During this Scientific Research, we established a SEM-EBSD system in Shizuoka University. Although our analyses on ultramylonites are still in progress, we could get some important results on peridotite study.Seismic anisotropy in the uppermost mantle, back-arc region of the northeast Japan arc : Petrophysical analyses of Ichinomegata peridotite xenolithsA dense network of seismic stations has been deployed across the northeast Japan arc to investigate mantle wedge structures. To attain independent petrophysical constraints, we determined the seismic properties of Ichinomegata mantle xenoliths from the back-arc region that were brought to the surface from the mantle lithosphere by volcanic eruptions. We calculated the seismic properties of the xenoliths from olivine and pyroxene crystal-preferred orientations and single crystal elastic constants. The small magnitude of measured S-wave splitting (delay time of 0.22 s in the area where the xenoliths were entrained) can be explained by the average seismic properties of mantle xenoliths for an approximately 20-km thick horizontal anisotropic layer, indicating that the mantle lithosphere could be one of the dominant sources of seismic anisotropy; this layer is possibly related to deformation in the uppermost mantle lithosphere due to back-arc spreading along the northeast Japan arc.

我们计划使用同步 EDS 和 EBSD 来研究超糜棱岩（一种位于延性剪切带的非常细粒的断层岩），以确定相分布和主要变形机制。之前已使用 EBSD 和光学显微镜对样品进行了分析，但分辨率限制阻碍了对更细粒度区域的详细分析。人们怀疑扩散蠕变（沿晶界的原子迁移）是这些区域的主要机制 - 使用 FEG-SEM 进行的分析可以验证这一假设。在这项科学研究期间，我们在静冈大学建立了SEM-EBSD系统。尽管我们对超糜棱岩的分析仍在进行中，但我们可以在橄榄岩研究方面获得一些重要结果。日本东北弧弧后地区上地幔的地震各向异性：Ichinomegata橄榄岩捕虏体的岩石物理分析日本东北弧部署了密集的地震台网，以研究地幔楔结构。为了获得独立的岩石物理约束，我们确定了弧后区域的 Ichinomegata 地幔捕虏体的地震特性，这些捕虏体是通过火山喷发从地幔岩石圈带到地表的。我们根据橄榄石和辉石晶体的择优取向和单晶弹性常数计算了捕虏体的地震特性。测量到的横波分裂幅度较小（夹带捕虏体的区域的延迟时间为 0.22 秒）可以用约 20 公里厚的水平各向异性层的地幔捕虏体的平均地震特性来解释，表明地幔岩石圈可能是地震各向异性的主要来源之一；该层可能与由于沿日本东北弧的弧后扩张而导致的最上地幔岩石圈的变形有关。

项目成果

Mantle anisotropy induced by the back-arc spreading of the northeast Japan arc : an insight from peridotite xenoliths of Megata volcano

日本东北弧弧后扩张引起的地幔各向异性：来自梅加塔火山橄榄岩捕虏体的见解

• 发表时间: 2005
• 期刊: Ofioliti 30
• 作者: Michibayashi;K.;Satsukawa;T.;Okamoto;A.;Michikura;K.;Abe;N
• 通讯作者: N

The Role of Pre-existing Mechanical Anisotropy on Shear Zone Development within Oceanic Mantle Lithosphere: an Example from the Oman Ophiolite

• DOI: 10.1093/petrology/egg099
• 发表时间: 2004-02
• 期刊: Journal of Petrology
• 影响因子: 3.9
• 作者: K. Michibayashi;D. Mainprice

2006. Misorientations of garnet aggregate within a vein : Implications for timescale of vein formation during metamorphism.

2006. 脉内石榴石聚集体的错误取向：对变质过程中脉形成时间尺度的影响。

• 期刊: Journal of Metamorphic Geology 24
• 作者: Okamoto;A.;Michibayashi;K.
• 通讯作者: K.

Misorientations of garnet aggregate within a vein : Implications for timescale of vein formation during metamorphism

脉内石榴石聚集体的错误取向：对变质过程中脉形成时间尺度的影响

• 发表时间: 2006
• 期刊: Journal of Metamorphic Geology 24
• 作者: Okamoto;A.;Michibayashi;K.
• 通讯作者: K.

Petrology of peridotite xenoliths from Iraya volcano, Philippines, and Implications for mantle wedge processes beneath arcs

菲律宾伊拉亚火山橄榄岩捕虏体的岩石学及其对弧下地幔楔过程的影响

• 发表时间: 2004
• 期刊: Journal of Petrology 45
• 作者: Lrai;S.;Takeda;S.;Michibayashi;K.;Kida.M.
• 通讯作者: Kida.M.