頁籤選單縮合
題名 | Mesoscopic Structures Developed in the Lichi Melange during the Arc-Continent Collision in the Taiwan Region=弧陸碰撞過程中利吉層的構造型態 |
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作者 | 陳文山; Chen, Wen-shan; |
期刊 | 中國地質學會會刊 |
出版日期 | 19970400 |
卷期 | 40:2 1997.04[民86.04] |
頁次 | 頁415-434 |
分類號 | 353.3 |
語文 | eng |
關鍵詞 | 利吉混洞層; 弧陸碰撞; Lichi melange; Arc-continent collision; |
英文摘要 | 利吉混同層是由充滿鱗片狀片理結構的灰黑色泥岩所構成,此構造特造徵是經由 隱沒與碰撞作用所造成,因此利吉層是屬於一種構造性質的隱沒一碰撞雜岩體。混同層中基 質泥受強烈的剪切作用而在片理面上產生許多的擦痕與條痕。全區的片理面上條痕呈一定向 的方位為左向平移,片理方向大致為北偏東 10 °一 30 °、傾角向東約 70 °一 90 ° ; 由上述的方向得知利吉混同層曾受一左向平移的剪切力所作用。另一包夾在基質泥中的岩 塊因受到不同形態的外力作用而於岩塊中產生多種型態的構造如剪切性伸張構造、伸張構造 與網狀結構。岩塊的長軸方向與片理面上的條痕方位相似,顯然岩塊與基質泥的受同一剪切 作用。從野外產狀與構造關係來看,岩塊中的剪切性伸張構造與片理構造是受到同一的剪切 作用,為一同期的構造產物。作者認為此構造是於後期碰撞過程中於碰撞帶中受到強烈的剪 切作用所造成。伸張構造產於厚層的砂岩岩塊中,呈一正斷層構造,斷層面與吵岩岩塊的層 面呈一高角度相交,但與片理面無特定方向關係。 伸張構造常呈 V 型的張裂,裂隙中或層 面之上常有碎裂的角礫岩,且裂隙中常有方解石脈;上述的結構目前皆已膠結固化,因此本 文認為此構造的形成與上述的剪切作用沒有關係,且形成於片理與剪切性仲張構造之前。網 狀結構是剪切作用所形成的一種網狀線紋構造,其常出現於厚層的砂岩岩塊之中.於顯微鏡 下可見紋中石英顆粒呈壓坪構造,顯然受一剪切作用所造成。網狀結構與上述的片理面無方 向性且線紋皆已膠結良好,顯然為一形成於片理與剪切性仲張構造之前的結構。本丈認為伸 張構造與網狀結構可能是隱沒作用時期位於增積岩體中剪切帶與部份岩層產生高壓帶中的構 造產物。 and is oblique at a high angle to the bedding. These extension fractures are commonly accompanied by normal faulting. In light of the research of deep-sea core, it is suggested that thecrack in the sandstone represents an intensive hydrofracture that occurred in the coherent strata beneath or above the shear zone in the accretionary prism. The web structure is a network of cataclastic shear planes in snadstone that are characterized by broken and less than average grain size relative to the surrounding rocks. The web and crack structures commonly observed in sandstone blocks within the melange that exhibit some degree of lithification and healing. The fact that the extension fracture and web structures cross cut by the hybrid fracture and scaly foliation in dicates that it formed before the collision. It is suggested that these structures reflect tectonic deformation and stratigraphic disruption during the underplating process. Thus, based on the mesoscopic structure, the structural style of the Lichi Melange is best described as a tectonic melange rather than a sedimentary melange or olistostrome. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。