台灣東北角萊萊地區裂隙分析

The Fracture analysis in the Lailai Area of Northeastern Taiwan

吳明諭(M.Y. Wu) ； 羅偉(L. Wei)

《鑛冶：中國鑛冶工程學會會刊》 63卷2期 (2019/06) Pp. 9-20

https://doi.org/10.30069/MM.201906_63(2).01

摘要

台灣東北角沿海地區露頭以海蝕平台為主，表面有許多錯綜複雜的裂隙幾何型樣貌，本研究使用無人機拍攝空拍照，並繪製出其裂隙線型，針對斷層構造使用斷層周圍裂隙幾何型態判釋斷層位置，分析該地區岩層中之裂隙，配合野外調查以截切關係及平移斷層之演化過程重建該岩層中之裂隙演化，初步結果發現台二線濱海公路110.5km處之裂隙可依照是否位在主斷層面上先區分成主斷層上裂隙及斷層周圍裂隙，其中斷層周圍裂隙依主要呈現之方向可再細分成三組。這四種裂隙之演化過程最少可分成三期， 第一期為N45˚W方向之裂隙發育，第二期為N40˚E及N15˚W方向之裂隙產生在第一期裂隙間，第三期受到N18˚W的最大應力使N12˚E方向的R-shears開始發育，並與前兩期裂隙連結再一起形成N27˚E方向之大裂縫，逐漸錯動產生現今看到之主斷層。

關鍵字

台灣東北角 ； 萊萊 ； 裂隙幾何型態 ； 斷層破壞帶

並列摘要

The coastal terrain of the northeastern Taiwan is dominated by wave-cut platforms with many complex fractures, which may be associated with various events through different time stages. Unmanned aerial vehicle was used to take photos above the wave-cut platform from which the fracture lines were mapped to categorize the fracture patterns. With the field fracture data, the fracture geometries were finalized into certain patterns to differentiate the main fault structure with the surrounding fractures. The study also used the principle of cross-cutting relationships and fault evolution to establish the fracture formation sequence in this area. Preliminary results showed that the fractures in the investigated area can be separated into at least three stages of fracture formation. A series of northwest-southeast fractures were formed in the first stage. The fractures in the second stage linked the adjacent fractures from the first stage and formed blocked shapes. In the third stage, N12˚E Riedel shears developed along N18˚W-S18˚E maximum compressive principal stress (σ1). The fractures of all previous stages developed into the damage zone and eventually formed the main fault structure.

並列關鍵字

Northeastern Taiwan ； Lailai ； Fracture geometries ； Fault damage zone