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Analysis of formation conditions for microcracking with fluid inclusions

流体包裹体微裂隙形成条件分析

基本信息

批准号：
04452077
负责人：
TAKESHITA Toru
金额：
$ 3.58万
依托单位：
HIROSHIMA UNIVERSITY (1993-1994)Ehime University (1992)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

The research supported by the grant has mainly been conducted on the Middle Miocene Momonoki Subgroup distributed in the Mukawa village, Kitakoma district, Yamanashi prefecture as a model field. The obtained results are following.(1) I have obtained many new findings concerning the stratigraphy and fold structure in the Momonoki Subgroup in the studied area.(2) A mylonitized contact aureole originated from the Momonoki Subgroup exisits along the Yakegizo granite, which presumably represents plastic dcformation of the wall rock associated with the intrusion of the granite.(3) Paleostress field in the sandsones from the Momonoki Subgroup has been inferred with deformation microstructures in the quartz detrital grains, namely defrormation lamellae, kink bands and healed microcracks. The paleostress field perhaps indicates that the one during the folding of the Momonoki Subgroup (Takeshita, 1995, in press).(4) Homogenization temperatures of the fluid inclusions along the healed microcracks range between 200-260ﾟC.When an appropriate pressure correction is applied to the homogenization temperatures, it is suggested that the quartz deformed at ca.300ﾟC.Furthermore, I investigated the deformation microstructures and homogenization temperatures of fluid inclusions in echelon quartz veins from the Sambagawa metamorphic bets, which truncated its fold structures. The following results have been obtained.(1) The preferred orientations of healed microcracks are characterized by orthogonal pattern, where each preferred orientation is normal to one of the principal stress axs.(2) The hmogenization temperatures in the quartz veins range from 150 to 350ﾟC,and the highest temperature group, 300-330ﾟC suggests that the fluid was trapped at ca.400ﾟC.The high temperature fluid could indicate the emergence of a new heat source after the elevation of the Sambagawa metamorphic belts.

本研究主要以山梨县北驹区穆川村的中中新世桃之亚群为研究对象。所得结果如下。(1)在研究区桃木亚群的地层和褶皱构造方面取得了许多新的发现。(2)一个起源于Momonoki亚群的糜棱岩化接触晕沿着于Yakegizo花岗岩中，推测它代表了与花岗岩侵入有关的围岩塑性变形。(3)根据桃木亚群砂岩中石英碎屑颗粒的变形显微结构，即变形纹层、扭折带和愈合微裂纹，推断了古应力场。古应力场可能反映了桃之亚群褶皱期间的古应力场（竹下，1995，出版中）。(4)流体包裹体沿着愈合的微裂纹的均匀化温度范围在200-260 ℃之间。当施加适当的压力校正的均匀化温度，建议石英变形约300 ℃。此外，我研究了变形显微结构和流体包裹体的均匀化温度在梯形石英脉从Sambagawa变质投注，截断其褶皱结构。取得了以下结果。(1)愈合微裂纹的择优取向具有正交图案的特征，其中每个择优取向垂直于主应力轴之一。(2)石英脉中的均一化温度为150 ~ 350 ℃，最高温度组为300-330 ℃，表明流体在400 ℃左右被捕获。高温流体可能表明桑巴川变质带抬升后出现了新的热源。