Internal Structure of the Median Tectonic Line fault zone revealed by analysis of continuous borehole core

一个钻孔在473.9m深处穿透中间构造线（MTL），该构造线是Ryoke花岗岩和Sanbagawa变质岩之间的边界。MTL断裂带的内部结构由岩心样品揭示，并在450℃至地表的不同温度条件下经历了一系列断裂事件。通过应力反演分析，将断裂带的演化历史划分为4个阶段，第一阶段断裂带经历了脆塑性转变。显微组织分析揭示了脆塑性过渡区周围的应力状态。蚀变矿物分析揭示了断裂带在演化过程中的热液活动。碳质物质的拉曼光谱揭示了脆性断裂过程中沿沿着MTL断裂带的摩擦加热。

A drill hole penetrates the Median Tectonic Line (MTL) at 473.9m depth which is the boundary between the Ryoke granitic rocks and the Sanbagawa metamorphic rocks. The internal structure of MTL fault zone was revealed by the drillcore samples, and has evolved through a series of faulting events under various temperature conditions from 450℃ to the surface. The evolution history of the fault zone can be divided into four stages based on the stress inversion analysis, and the fault zone experienced the brittle-plastic transition at the first stage during their evolution. A microstructure analysis revealed the stress state around the brittle-plastic transition zone. Analyses of altered minerals revealed the hydrothermal activities within the fault zone during the evolution. Raman spectroscopy of carbonaceous matter revealed the frictional heating along the MTL fault zone during the brittle faulting.