| DC 欄位 |
值 |
語言 |
| DC.contributor | 應用地質研究所 | zh_TW |
| DC.creator | 王廷瑜 | zh_TW |
| DC.creator | Ting-Yu Wang | en_US |
| dc.date.accessioned | 2021-1-14T07:39:07Z | |
| dc.date.available | 2021-1-14T07:39:07Z | |
| dc.date.issued | 2021 | |
| dc.identifier.uri | http://ir.lib.ncu.edu.tw:88/thesis/view_etd.asp?URN=107624009 | |
| dc.contributor.department | 應用地質研究所 | zh_TW |
| DC.description | 國立中央大學 | zh_TW |
| DC.description | National Central University | en_US |
| dc.description.abstract | 臺灣中部的初鄉斷層為車籠埔斷層的分支斷層，呈東北-西南走向的活動動層，位於車籠埔斷層至雙冬斷層之間，東北側往雙冬斷層延伸；西南側則併入車籠埔斷層。此斷層於濁水溪以及東埔蚋溪河岸出露良好且連續的露頭，兩溪之間多受植被覆蓋難以確定斷層跡位置，導致前人繪製的斷層跡存在差異。因此，本研究在針對濁水溪與東埔蚋溪之間的初鄉底地區進行地電阻探測，為了納入所有可能為斷層跡的區域，將調查寬度設為812公尺，由於地形的限制而將部分線型西側的測線範圍修正為往東側延伸。本研究進行電阻率影像剖面法（Electrical Resistivity Tomography, ERT）施測時採用電極間距為8公尺，並配合非傳統的CPP陣列電極配置以增加放電電極的數量使施測過程更加快速。
本研究將施測所獲得的資料以EarthImager2D軟體進行反演，建立地下的電阻率的分布情形。反演結果顯示，本區域電阻率區間為10~100Ω-m，剖面近地表處呈現較高的電阻率（約90~100Ω-m）；剖面中線偏西側存在地電阻變化異常的高電阻率區（約60~100Ω-m）與其相鄰兩側的低電阻率區（約10~25Ω-m）；其餘區域的電阻率則均勻且無明顯變化，因此除垂直向於淺層存在一道電阻率不連續面外，水平向亦可判釋出四道。剖面中電性變化較明顯的區域推測可能為斷層通過的位置，因此針對剖面中段區域鑽取兩孔岩心搭配地表露頭資料驗證斷層是否通過並了解地下構造。
為了解電阻率變化所指示的地質意義，本研究於鑽取的兩口岩心分別進行岩心判釋與採樣，並使用岩心樣本進行室內電阻率試驗。根據岩心的判釋與電阻率剖面的對比，顯示剖面中電阻率變化處大致與岩性變化處接近，且淺部較高電阻率的區域，由地表露頭證實為崩積層所致。室內電阻率試驗結果顯示，影響電阻率變化最顯著的因素為含水量，其次則為岩石特性。透過室內電阻率試驗的結果對比電阻率剖面，本研究認為剖面變化異常高電阻率區域與低電阻率區域的岩層很可能存在大量裂隙，若裂隙未充滿水分將形成高電阻率區，反之則為低電阻率區；其餘電阻率無明顯變化區域之岩層應較為連續且含水量無顯著差異。而透過岩心紀錄中出現的大量破裂面顯示剖面中的電性不連續帶可能為初鄉斷層帶，此斷層帶的西北緣離地電阻測線西北端水平距離約130公尺，水平寬度約370公尺，以55°向東南傾向下延伸，比較現地露頭資料發現初鄉1A井西側區域岩層為70°至76°，與初鄉1A井岩心淺部傾角約50°，呈現岩層位態有往西變得更陡的趨勢，顯示於剖面中最西側的電性不連續面可能為初鄉主斷層通過的位置，而其餘的電性不連續面，亦有部分與岩心中的剪切帶位置約略吻合，推測可能為其次要斷層。 | zh_TW |
| dc.description.abstract | The Chusiang fault in central Taiwan is located between the Chelongpu fault and the Shuangdong fault. It extends northeastwards to the Shuangdong fault and merges into the Chelongpu fault to the southwest. The Chushiang fault is difficult to trace because it’s mostly covered by vegetation, except the Zhuoshui riverbank and Dongpuri riverbank. Several versions of fault traces proposed by previous studies are noticeably different. In this study, Electrical Resistivity Tomography (ERT) was used with an electrode spacing of 8 meters, and the non-traditional CPP array electrode configuration was used to increase the number of discharge electrodes to make the measuring process faster. The survey line trending NW to SE was up as 812 meters long in order to cover all the probable extent that the fault trace may pass through.
The data will be adapted to perform the inversion of the electrical resistivity profile with the EarthImager 2D software in order to decipher the distribution of the underground resistivity.
According to the inversion results, the resistivity ranges from 10 to 100 Ω-m over the whole section, and it exhibits relatively high values (about 90-100 Ω-m) in the sector near the ground surface. Beneath this sector, there is an abnormally high resistivity of about 60-100 Ω-m appearing in an extent of about 60 meters wide in the distance of one-third of the section from the northwest end. Two sectors with low resistivity of about 10-25 Ω-m, are adjacent to this high-resistivity extent, 30 meters wide to the NW and 130 meters to the SE, respectively. The resistivity of the remaining sectors is relatively uniform without much variation. Therefore, besides the resistivity discontinuity beneath the high-resistivity sector sub-parallel to the ground, four resistivity discontinuities can also be laterally distinguished.
Two boreholes on the survey line and laboratory resistivity tests were conducted to decipher the variations in the resistivity profile. Integrating the logging of two boreholes and the ERT, it is shown that the resistivity change in the profile is roughly close to the lithological boundary, and the sector with high resistivity near the ground surface is correlated to the unsaturated colluvium or weathered soil which could be confirmed by the outcrops on the ground surface. The laboratory resistivity test results show that the main significant factor affecting resistivity variation is water content, followed by rock properties. Comparing the result from the ERT with the one from the laboratory resistivity test, we believe that there are a lot of fractures existing within the strata in those regions, including the sector of abnormally high resistivity and its two adjacent low-resistivity sectors. However, the high-resistivity area likely means that the fractures contain no water and vice versa. The strata in the remaining areas without much variation in resistivity should be relatively intact and have no significant difference in water content.
The region with high resistivity variation bounded by electrical discontinuities may be the Chusiang fault zone inferred from the dense fracture distribution and highly localized deformation in the rock cores. The northwestern edge of the fault zone is about 130 meters away from the northwest endpoint of the survey line, the horizontal width is about 370 meters, and the fault zone dips to the southeast at the angle of 55°. Comparing with the outcrops data, it is found that the dip angles of strata on the west side of borehole CS-1A are 70° to 76°, higher than the dip angle at the shallow part which is about 50°. This indicates the electrical discontinuity showed on the westernmost side of the profile may be the position where the Chusiang main fault passes. The remaining electrical discontinuities may be the branch faults based on the evidence that the electrical discontinuities which the borehole penetrated correlate with shear zones appearing in the rock cores. | en_US |
| DC.subject | 初鄉斷層 | zh_TW |
| DC.subject | 電阻率影像剖面 | zh_TW |
| DC.subject | 室內電阻率 | zh_TW |
| DC.subject | Chusiang fault | en_US |
| DC.subject | Electrical Resistivity Tomography | en_US |
| DC.subject | Laboratory resistivity test | en_US |
| DC.title | 利用地電阻影像法與室內電阻率試驗探討地下構造特性 —以臺灣中部初鄉斷層為例 | zh_TW |
| dc.language.iso | zh-TW | zh-TW |
| DC.title | Investigation of the Subsurface Structure by Using Electrical Resistivity Tomography and Laboratory Resistivity Test – A Case Study on the Chusiang Fault, Central Taiwan | en_US |
| DC.type | 博碩士論文 | zh_TW |
| DC.type | thesis | en_US |
| DC.publisher | National Central University | en_US |