| Summary: | 碩士 === 國立臺北科技大學 === 資源工程研究所 === 106 === Taiwan is located at the Philippine Sea Plate and the Eurasian Plate oblique collision orogenic belt, with most of mountains in NE-SW direction, and gradually changing to E-W in the northeastern region, which exposes many complicated geological structures.
To understand the orogenic history of Taiwan, this research focuses on Nanfangao area and studies the occurrence, distribution, and textural fabrics of quartz vein, in order to construct the tectonic environment through fluid inclusions development in the northern tip of the Central Range of Taiwan.
The main lithology of this area is slate and interbedded slate with metamorphic sandstone, there are many geological phenomena such as well-developed slate cleavage, faults, folds and quartz veins. The cleavage in this area is mostly in west-northwest direction. The most common small‐scale geologic structures in this area are plenty of fractures, quartz veins and fluid inclusions. Therefore, in order to realize the geological history in slate belt, the inclusions can provide information about the existing conditions during the deformation of enclosing mineral.
Based on the occurrence in field work and thin sections, the quartz veins can be divided into three categories. First is the lenticular quartz veins perpendicular to the bedding in metamorphic sandstone; secondly, folded quartz veins in the slate parallel to the cleavage; thirdly, the echelon arranged quartz veins crosscutting cleavage.
The result of the analysis in the first group shows that the density of the fluid inclusions is 5 wt% and the range of the homogenization temperature is 250-350°C; the second group of the quartz veins is parallel to the cleavage, and developed under the high pore pressure in the stage of the rapid uplift. The second group shows that the density of the fluid inclusions is 5 wt% and the range of the homogenization temperature is 250-260°C; finally, the third group of the quartz veins shows that the density of the fluid inclusions is 3 wt% and the range of the homogenization temperature is 250-300°C the fourth group of the quartz veins shows that the density of the fluid inclusions is 3 wt% and the range of the homogenization temperature is 200-250°C.
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