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|Title: ||台灣東部石梯坪地區變形條帶之研究;Study of deformation bands in Shihtiping, eastern Taiwan|
|Keywords: ||變形條帶;石梯坪;高孔隙岩石;中酸性凝灰岩;deformation band;Shihtiping;porous rock;ignimbrite|
|Issue Date: ||2015-09-23 15:11:57 (UTC+8)|
綜合以上結果，推斷石梯坪的變形條帶形成機制包含壓實、壓碎與剪動作用，從運動學角度將其歸類在壓密剪力型的變形條帶(Compactional shear band)，以機制分類則屬於壓碎型變形條帶(Cataclastic band)。從變形條帶的分佈情況與岩層位態之關係分析，研判其形成可能與區域向斜同期或之後的產物，非伴隨鄰近的大港口斷層生成。
;Deformation band, a tabular structure, pervades in the Shihtiping marine plateform composed of mainly Miocene ignimbrite. The older volcanic breccia composing the hills west of Shitiping conformably tilted against the ignimbrite. The north-south-trending Takangkou Fault thrusts the Miocene volcanic breccia onto the Pleistocene sedimentary rocks at about 1-2 km west of Shihtiping. There is a N14°E-trending syncline cropped out in Shihtiping. The deformation bands are commonly exposed as cluster zone composed of several individuals in Shihtiping. They can be traced easily because they are protruding on the ground surface. The cluster zones range from 0.1 to15 cm in width, up to 10 m in length and from 1 to 20 cm in total separation. The deformation bands with orientations of ENE and NW are widely distributed while those with orientations of NS and EW are locally found. The dip angles of all sets range from 50° to 90°. The syncline seems to have no effect to the deformation bands. The porosities of host rock and deformation band are respectively 16% and 4% calculated from image analysis. Through permeability test, conductivities in deformation bands of two samples are 0.22 and 0.52 md which reduce 2 to3 orders. Based on microscopic examination, minerals in the deformation bands usually include plagioclase, hornblende and augite. The Mineral assemblage is the same as the one in host rock but grains in the band are relatively smaller and more intact (i.e. not fractured). Thus, it results in tighter packing and lower porosity within deformation bands.
To sum up my findings, the deformation bands in Shihtiping were formed by compaction, shear and cataclasis after the syncline or simultaneously. They can be classified as compactional shear band in terms of kinematics and cataclastic band in terms of mechanics. They do not accompany the Takangkou Fault but reflect the regional paleostress.
|Appears in Collections:||[應用地質研究所] 博碩士論文|
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