花東縱谷斷層之地電研究

An Electric Resistivity Study of the Faults in the Taitung Longitudinal Valley, Eastern Taiwan.

簡立凱(Li-Kai Chien)

指導教授 ： 陳平護 ； 顏宏元

國立中央大學/地球科學學院/地球科學系/博士(2015年)

摘要

為研究花東縱谷之地質構造與活動，本研究採用電阻率影像剖面探測之雙極排列法完成25條電阻率影像剖面和22個音頻大地電磁法測點，調查位於花東縱谷內的8條斷層，針對斷層及其破碎帶兩側地表下構造，由施測資料解釋結果所得之地層電阻率，根據電阻率譜、井之岩芯紀錄與地質資料，分析斷層帶特性、位態與形貌，研判斷層上、下盤的電阻率構造所對應的地層及其岩性，得到以下結果：
(1)米崙斷層在美崙溪床上有寬的破碎帶，其寬度範圍達640公尺以上，在深部有含海水的可能。
(2)嶺頂斷層之位置在月眉地區之花蓮溪溪床中，兩側之淺部地層為沖積層，斷層東側深部地層之電阻率大於 150 Ω-m為都鑾山層，西側深部地層之電阻率小於20 Ω-m為泥岩層。
(3)月眉斷層於月眉村有兩處斷裂帶，一在台193公路旁為主斷裂帶，另一在其東方約600公尺處。斷裂帶兩側之淺部地層相似。
(4)鍋蓋樑剖面中電性不連續顯示瑞穗斷層主斷裂面以高角度向東南方向傾斜，在舞鶴礫岩中有錯動，上盤抬升110公尺；舞鶴礫岩之分布向東延伸至鍋蓋樑測線的東側。
(5)客城、長良與崙天-秀巒測區之施測結果，研判施測剖面中的電性不連續為玉里斷層，斷層面向東傾斜。中央山脈板岩層位於下盤深部位置，在玉里地區電阻率150-400Ω-m，在富里崙天地區電阻率500-800Ω-m。上盤為縱谷堆積，在玉里地區電阻率400-1000Ω-m、在崙天-秀巒地區電阻率100-400Ω-m。玉里斷層經客城向南延伸通過長良至崙天-秀巒地區但未達池上地區
(6)奇美斷層主斷層帶通過泰林測區之泰林三測線，於利吉層中發生錯動，斷層面朝東南傾斜；分支斷層通過泰林二測線，在礫石層中有錯動，斷層面朝東南傾斜。
(7)東寧、九岸溪、萬安與瑞隆隆四個測區6條RIP測線，施測結果之剖面中電性不連續研判為池上斷層的位置，斷層面朝東南方向傾斜，上盤為電阻率小於10Ω-m之利吉層，下盤為電阻率100-1000Ω-m之縱谷堆積。
(8)龍田與田寮施測結果之剖面中，電性不連續研判為鹿野斷層，斷層面朝東傾斜，上盤組成為卑南山礫岩，電阻率300-1500Ω-m，下盤組成為中央山脈板岩層，電阻率100-1000Ω-m。鹿野斷層往南延伸通過田寮測區。
(9)在卑南測區中卑南山斷層之斷層帶，近地表處寬度約240公尺，斷層帶朝東南傾斜，上盤組成為縱谷沖積層，電阻率100-300Ω-m，下盤之淺部為縱谷沖積層，深部為卑南山礫岩，其電阻率多大於1000Ω-m。卑南山斷層往南延伸通過卑南測線。

關鍵字

花東縱谷 ； 地電法 ； 電磁波法

並列摘要

In order to study the geological structures and activities of the faults in the Taitung Longitudinal Valley, we conducted an electric resistivity surveys consisting of twenty-five resistivity image profilings and an electromagnetic prospecting of twenty-two soundings to investigate the electric resistivities and attitude of layers and the subsurface geological structures of the eight faults. The results show as followings：
(1)The Milun Fault has an wide fault zone located on the Meilun River bed. The fracture zone is over 640 meters wide and seawater may exist deep within the fracture zone.
(2)The Lingding Fault passes through Hualien River bed in the Yuemei area. The shallow strata on both sides of the fault are alluvium. The deep part in the eastern side of the fault is the Tuluanshan Formation with a resistivity higher than 150 Ω-m. The deep part in the western side is a mudstone with a resistivity lower than 20 Ω-m.
(3)The Yuemei Fault has two fracture zones near the Yuemei village. One is the main fracture zone which is near the road of Tai 193 and the other is located around 600 meters east of Tai 193. The shallow strata on both sides of the fault are similar.
(4)The Rueyshui Fault dips southeastwards with a high angle at Guogailiang profile. The hanging wall of the fault has been uplifted 110 meters. The Wuhe Conglomerate extends eastwards to the eastern side of the fault.
(5)The location of the Yuli Fault is clearly presented in the Kecheng, Changliang and Luntian-Xiuluan area. The fault zone dips southeastwards. The slate of the Central Range exists in the deeper part of the footwall with a resistivity 150-400 Ω-m in the Yuli area and 500-800 Ω-m in the Fuli area. The hanging wall consists of alluvium which has a resistivity 400-1000 Ω-m in the Yuli area and rift valley deposits which has a resistivity 100-400 Ω-m in Fuli area. The Yuli Fault exists southwards in the Kecheng and Changliang areas and extends to Luntian-Xiuluan areas and ends before Chihshang area.
(6)The main fracture zone of the Chimei Fault which passes through Tailin 3 profile developed in the Lichi Formation and dips southeastwards. The branch fault which passes through Tailin 2 profile developed in the gravel bed and dips southeastwards .
(7)The Chihshang Fault dips southeastwards in the Dongning, Jiuan River, Wanan and Ruilong areas. The hanging wall is the Lichi Formation which has a resistivity lower than 10 Ω-m and the footwall is the rift valley deposits with a resistivity 100-1000 Ω-m.
(8)The Luye Fault dips eastwards in the Longtian and Tianliao areas. The hanging wall is the Beinanshan Conglomerate with a resistivity 300-1500 Ω-m and the footwall is the slate of the Central Range which has a resistivity 100-1000 Ω-m. The Luyeh Fault passes through the Tianliao area southwards.
(9)The fracture zone of the Beinanshan Fault is about 240 meters wide near the ground surface and dips southeastwards in the Beinan area. The hanging wall is the gravel bed of rift valley alluvium which has a resistivity 100-300 Ω-m. The shallow part of the footwall is the rift valley alluvium. The deep part of the footwall is Beinanshan Conglomerate which has a resistivity exceeds 1000 Ω-m. The Beinanshan fault passes southwards through the Beinan profile.

參考文獻

許華杞、林玉峰、江文卿、蔣正國、恆石幸正、世井洋一，花蓮地區之地殼變動觀測與地震預測研究。大漢學報，第九期，73-80頁，1995。

紀權窅，南段花東縱谷之新期構造研究-利吉斷層與鹿野斷層的活動特性，國立台灣大學地質科學研究所，碩士論文，共84頁，2007。

鍾令和， 1951年池上-玉里地震地表破裂與其所指示之新構造意義，國立臺灣大學地質學研究所，碩士論文，共168頁，2003。

楊貴三，台灣活動斷層的地形學研究-特論活動斷層與地形面的關係。私立中國文化大學地學研究所，博士論文，178頁，1986。

Barrier, E. and Angelier, J., Active collision in eastern Taiwan, the Coastal Range: Mem. Geol. Soc. China, 7, 135-159., 1986.