Reconstruction of the paleostress field on the basis of 3-D analyzes of healed miocrocracks in granitic rocks

基于花岗岩中愈合微裂纹的 3D 分析重建古应力场

基本信息

批准号：
17540439
负责人：
TAKAGI Hideo
金额：
$ 2.36万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17540439/
关键词：
healed microcrack sealed microcrack paleostress field Ryoke Granite collision of the Izu arc Tanzawa Tonalite Median Tectonic Line 伊豆弧の衝突古応力場領家花崗岩

项目摘要

To estimate the influence of the bending of the Median Tectonic Line(MTL) by the late Miocene collision of the Izu-Ogasawara arc, we examined the 3-D orientations of healed microcracks in the Ryoke granitic rocks and the Tanzawa Tonalite and determined the paleostress field. The results are as follows :1. δHmax directions recorded as the orientation of healed microcracks from the Nojima Granodiorite(Awaji Island), Misugi Tonalite(Mie Pref.) and Shinshiro Tonalite(Aichi Pref.)are nearly parallel to the current strike of the MTL. These results suggest that the microcrack-bearing granitic bodies along the MTL are rotated together with the MTL during the arc-arc collision. However, those from the Takato Granite(Nagano Pref.) are almost normal to that of the MTL. It is not able to be explained by the bending, and open to research more.2. δHmax directions recorded as the orientation of both healed and sealed microcracks from the Tanzawa Tonalite which was collided at c. 5Ma are fairly constant throughout the body(NNE-SSW). Geothermometry on fluid inclusions constituting healed microcracks suggest that the formation of them was occurred at the condition of 300〜400℃. This trend was explained by the divergent δHmax trajectories at the northeastern side of colliding center which has the movement direction of NW.

为了估计中循环的弯曲线（MTL）的弯曲影响，通过中新世晚期碰撞，我们检查了Ryoke Granite Rocks和Tanzawa Tonalite中愈合的微裂纹的3-D方向，并确定了古植物田。结果如下：1。 ΔHmax方向记录为从Nojima花岗岩（Awaji Island），Misugi Tonalite（Mie Pref。）和Shinshiro Tonalite（Aichi Pref。）的愈合的微裂纹方向几乎平行于MTL的当前打击。这些结果表明，在ARC-ARC碰撞期间，沿MTL的含微裂痕的花岗岩体与MTL一起旋转。然而，高铁花岗岩（Nagano pref。）的人几乎与MTL的那些人几乎正常。弯曲无法解释它，并开放更多研究。2。 ΔHmax方向记录为从坦泽（Tanzawa）Tonalite的愈合和密封的微裂纹的方向，该方向在C处碰撞。 5mA在整个身体（NNE-SSW）中相当恒定。构成愈合的微裂纹的流体夹杂物上的地热法表明，它们的形成是在300-400℃的情况下发生的。这种趋势是由具有NW运动方向的碰撞中心东北侧的不同ΔHmax轨迹来解释的。