岩石劈理是指在變形和變質過程中,所形成的一組相互平行而且間隔緊密的次生透入性(secondary penetrative)面狀組構元素(fabric element)。而岩石劈理為臺灣中央山脈變質岩中最普遍的次生面狀構造,故常以岩石劈理的觀察與分析為基礎,針對中央山脈板岩區及片岩區岩體的變形作用及區域地質構造進行研究。 中部橫貫公路大禹嶺地區位於臺灣中央山脈板岩帶,區域地質構造為一複向斜構造,本研究藉由岩性、劈理位態、劈理形態及微構造分析,了解大禹嶺複向斜和岩石劈理的形成關係。另外已知岩石劈理的形態及種類主要和岩性及變形條件有關,而岩石劈理在發育時的影響因素有岩性、所處區域地質構造部位、溫壓條件、變質度、深埋深度及劈理的生成機制等,所以本研究先討論影響岩石劈理發育的因素,再由岩石劈理的發育討論其與區域地質構造及造山運動的關係。 由本研究可知影響岩石劈理發育的因素主要有岩體原始之岩性,複向斜生成時的構造作用及構造部位,以及岩體內部所發生的劈理生成機制三點。而與大禹嶺複向斜的演化關係中,也因受其影響而在不同時期發育成不同形態的岩石劈理。最後與蓬萊造山運動的時間對比,得知岩石劈理多於上新世早期,即深埋於地底時發育完成,但會因為後期韌性剪動構造的發生而改變。
Rock cleavage is a set of closely spaced secondary planar parallel fabric element, which developed during the deformation and metamorphism. Because of rock cleavage is also the most common secondary, planar structure in the metamorphic rock of Central Range of Taiwan. So, rock cleavage is the very important key to study the relationship between the rock deformation and the regional structure evolution in the Central Range of Taiwan. This study focuses on the morphology, textures, and microstructures of the rock cleavage on the Tayuling area. The Tayuling area is located at the Central Range Slate Belt of Taiwan and the regional geology has been study clearly. There is a synclinorium structure in this area. According to the analysis of the lithologic units, attitude of cleavage, morphology of cleavage and microstructures, showed that the rock cleavage developed during different evolution stages of the Tayuling synclinorium.