- 學位論文
臺灣中央山脈北段大理岩地區岩理組構分析
The Textural Fabrics Analysis of the Marble Complex Exposed in the Northern Central Range of Taiwan
摘要
臺灣的大地構造研究多年來，碰撞前的大地構造演化與臺灣先第三紀的大地構造，因對大南澳變質雜岩中部份地質資料的解讀不同，或因目前資料的不足，無法進一步突破。台灣的東部的大理岩分布面積廣大完整且連續、形成時間較長、地質構造記錄較完整等特性，因此，藉由大理岩的組構分析，對了解大南澳變質雜岩應是一可行的途徑。 本研究根據野外產狀初步將大理岩分為四大類，並於室內分析其組構，量化的分析包含了顆粒大小、形狀、方向性，組構的順向排列分析使用沙佛(SURFOR)。研究結果顯示，第一類大理岩岩體最連續，且為厚層狀、塊狀之大理岩，分佈的範圍最廣，位於大南澳片岩區之東側，顆粒粒度約為100-450μm，顆粒形狀為等向、多邊形，方解石顆粒邊界平直；第二類大理岩多為層狀，與各種片岩夾雜出露，顆粒大小約40μm至180μm間，顆粒形狀為等粒狀及拉長狀，部分略呈碎屑狀，顆粒邊界部分平直、部分參差不齊；第三類大理岩多為獨立岩體成透鏡狀，顆粒形狀多被拉長，有順向排列，多邊形顆粒，顆粒大小約40μm至140μm間，顆粒邊界平直到彎曲狀，第二類與第三類大理岩則分佈在大南澳片岩區之西側，交錯出露於地表；第四類大理岩顆粒大小約為30μm至90μm間，顆粒形狀為拉長狀，顆粒邊界彎曲至參差不齊，並有明顯之順向排列，成透鏡狀分布於板岩帶中。 此外本研究針對不同產狀之大理岩分析其組構發現，在顆粒度上第一類、第四類大理岩是不同於第二類及第三類，與前人研究結果相比，顆粒度越大年代越老且無順向排列；就形狀、方向性與構造間的關係來看，還需要進一步資料，才能分析其影響因素。使用沙佛於方解石礦物的方向性排列分析上，也有明顯的成效，對於肉眼不易分辨之情形也可藉由沙佛計算來發現其差異性。另人工圈繪礦物的顆粒雖然費時費力，但對於順向排列不明顯處，有其優勢存在；而數位影像的選取優點為快速、方便，但必須運用於順向排列明顯之礦物顆粒，其分析結果較具有可信度。
並列摘要
The geological structures of the Central Range on Taiwan have been studied for many years, but there are still many unknown waiting to find out. Although that geologic mapping is not easy in the Central Range of Taiwan for the complicated structures. Study on the microstructures that take place during deformation is probably a key for an understanding of deformed rocks and for the interpretation of the geological significance of tectonic structures on the Central Range of Taiwan. From studying of microstructures and textural fabrics, we can get a better understanding of the deformation mechanism and from which we can also reconstruct the physical conditions during deformation. There are a conspicuous belt extending widely in the northern Central Range on Taiwan and consists the monotonous metamorphosed limestone or marble. There are of diverse color and grain size and range from massive to well-foliated. This study is tried to analysis microstructures and textural fabrics of those marbles which including their geometric and kinematic properties. It is also developed some methods of strain analysis which can be applied in interpretation of the deformation paths.