臺灣東北角萊萊海岸地區煌斑岩脈及其圍岩之斷層及節理分析

The Analysis on Joint and Fault of the Dike and its wall rock in the Lailai Area of Northeastern Taiwan

王證豪(Zheng-Hao Wang)

指導教授 ： 羅偉

國立臺北科技大學/工程學院/資源工程研究所/碩士(2013年)

摘要

臺灣東北角萊萊海岸出露的地層為大桶山層，岩性主要為灰色砂岩與灰黑色頁岩互層，岩層走向為東北-西南方向，此地區因受到區域性構造作用，使砂頁岩互層上節理發達。而一系列的煌斑岩脈之間則受到了正斷層(normal fault)或逆斷層(thrust fault)及走向滑移斷層(strike-slip fault)的影響，造成煌斑岩脈彼此間分離或錯移。並因砂岩與頁岩互層因含有數組節理而較為破碎，與煌斑岩脈比較起來抗風化作用能力較差，最後在持續的侵蝕作用下造成一條條的煌斑岩脈佇立在萊萊海岸的海蝕平台上。
本研究調查萊萊海岸之砂頁岩互層與煌斑岩脈在斷層及節理作用下的差異性，已知此煌斑岩脈上至少受到四個方向的斷層作用，分別為東西向、南北向及煌斑岩脈延伸方向均有發現斷層作用遺留的證據，由斷層擦痕、張力裂隙、雷氏剪裂構造等的次要構造來進行斷層的滑動方向的判斷。節理部分則是以各區量取節理位態以直方圖(histogram)或極點密度等值圖(contour diagram)來統計分析。
由野外觀察與節理位態分布以及由在煌斑岩脈上之斷層滑動方向分析統計，得知此區煌斑岩脈受到之應力作用方向有三個階段，第一階段為100°-115°方向之擠壓應力，第二階段為近南北向之剪應力，第三階段為85°-100°的剪應力與約10°方向張應力。

關鍵字

萊萊岩脈 ； 節理 ； 斷層

並列摘要

The strata of Tatungshan formation is well exposed in Lailai area of the northeastern coast of Taiwan. The dominant lithological is interbedded units of gray sandstone and shale. The rock layer bedding direction is northeast-southwest. This area has many joints which shows of sandstone and shale. Affected by normal fault, thrust fault and strike-slip fault of the dike, caused by separation and movement.
We investigated the difference of sandstone and shale of interbedded units on faults and joints under the action. This is known by at least four directions of faulting on dike. Respectively, we know the E-W, N-S and extending direction of dike. By the slickenside, tension cracks, Riedel shear structure, to determine the direction of sliding. The measured strike of joint to do histogram or contour diagram for statistical analysis.
The analysis on faults and joints in field investigation results, divided into three stages. The first stage is 100°-115° direction of the compressive stress. The second stage is near the north-south of shear stress. The third stage is 85°-100° of shear stress and about 10° direction of extension stress.

並列關鍵字

Lailai dike ； joint ； fault

參考文獻

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