Electron microscopic characterization and X-ray pole-figure diffraction of mudstones and fault gouges from northern Lungchuan Fault, southern Taiwan
| Autor: | Chia-ChunHuang, 黃家俊 |
|---|---|
| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Microstructures of mudstones and fault gouges from northern Lungchuan Fault, southern Taiwan were investigated by X-ray powder and pole-figure diffraction and polarized light and scanning and transmission electron microscopy. The mineral constitutients and abundances are similar and illite is predominantly a 2M1 polytype in both mudstones and fault gouges but a significantly poorer illite crystallinity was measured in the bulk fault gouges in association with a significant size reduction of detrital silicate grains and clay pockets enriched and aligned in the vicinity of various micro-shear zones therein. Illite (002) pole-figure analyses of the fault gouges showed a main pole arising from the Y-shear fabric (parallel to the main shear-zone boundary) or overlapping Y- and R1-shear (conjugate shear) fabrics, and a minor pole attributable to the P-shear fabric of the Riedel shear microstructures exhibited in the gouge specimens. The intensity of the main pole was 5.86 m.r.d., similar to that of unfaulted mudstones. Chlorite (002) pole-figure patterns of the gouge specimens displayed a pole with an orientation and intensity (3.39 m.r.d.) close to those of the illite minor pole. The chlorite (002) pole intensity of mudstones was averaged 2.56 m.r.d. Transmission electron microscope observations indicated that the oriented clay pockets in the shear zones consist largely of parallel to subparallel 2M1 illite packets less than 20 nm in thickness. Development of the aforementioned microstructures and therefore scaly microfabrics could lower the strength of faulted rocks and facilitate aseismic creeping in the studied fault area. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|