俞何興2006-07-252018-06-282006-07-252018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/14864約在五佰萬年前，台灣造山帶形 成由北而南，沿著中國大陸邊緣與呂 宋島弧斜向碰撞帶發育。晚上新世期 間台灣造山帶的荷重使得歐亞板塊最 東緣向下撓曲，而形成台灣造山帶西 側之前陸盆地。南海接近台灣西南海 域處的地体構造呈現一種向北過渡的 現象，南海板塊沿著馬尼拉海溝北部 向東隱沒，向北接近台灣西南海域處 則進入了初期碰撞，歐亞板塊過渡帶 地殼向東隱沒至菲律賓海板塊之下。 北緯廿一度以北，班氏隱沒帶的下傾 角度增加至80 度，在台灣西南海域初 期碰撞區域，馬尼拉海溝變淺而且失 去了海溝形貌的特徵，其最北端逐漸 連結近乎南北走向的澎湖海底峽谷最 南端。 在台灣西南海域初期碰撞區 域，聚合地体構造的特徵就是中國大 陸邊緣開始撓曲，而台灣造山帶向西 前進，形成两個截然不同的海洋盒 地。中國大陸邊緣一側為邊緣海盆 地，南海大陸斜坡成為其盆地底部， 而相鄰台灣西南海域可以視為一個楔 形體上部盆地，位於海下台灣造山楔 形體之上，接受來自台灣的沈積物。 造山帶沈積物逐漸堆覆在西側中國大 陸被動邊緣之上，同時使得楔形體上 部盆地的沈積物厚度增加，盆地變 淺。沈積相顯示深海泥質沈積物逐漸 被淺海沈積物覆蓋。楔形體上部盆地 的沈積物正被擠壓變形成泥貫入体及 一系列向西聚合的斷層及褶皺，伴随 著猪背盆地，使得海床呈現交互的海 脊及海槽。中國大陸邊緣的上新世及 第四紀沈積物則少構造變形，來自弧 陸碰撞的擠壓，影響不大。中國大陸 邊緣的斜坡呈現S 型曲度，代表原始 堆積的沈積環境。海底峽谷主要發生 在上部斜坡區域，切割成不規則的海 床形貌，展現海底侵蝕作用。The Taiwan orogen has formed by oblique collision from north to south between the Luzon Arc and the Chinese margin since about 5 Ma. West of the Taiwan orogen the western Taiwan foreland basin has formed during the Late Pliocene as the flexural response of the Eurasian plate to loading of the Taiwan orogen. Tectonics of the South China Sea near southern Taiwan exhibits a progressive northward transition from oceanic subduction along the Manila Trench to the incipient collision zone offshore southern Taiwan where the continental crust of the Eurasian plate subducts beneath the Philippine Sea plate. North of 21 N, dip angles of the Benioff zone incease up to 80 degrees in the incipient collision zone where the Manila Trench becomes shallower and gradually loses its morphological identify and finally mergers into the nearly N-S trending Penghu Submarine Canyon. Convegent tectonics in the initial collision mainly represented by the beginning of flexure of the Chinese margin with westward migrating overthrust belt of Taiwan, forming two distinct basins. On the 3 Chinese side, the marginal sea basin becomes smaller and is underlain by the South China Sea Slope but on the Taiwan margin a wedge-top basin has formed above the frontal thrust sheets of the Taiwan orogenic wedge. Sediments derived from the Taiwan orogen progressively overlie strata of the Chinese margin, resulting in increasing sediment thickness and shallowing of the floor of the wedge-top basin from south to north. Sedimentary facies shows that offshore deep-water mud is gradationally overlain by sahllow marine sediments. Sediments of the wedge-top basin are being actively deformed into mud diapiric intrusions and a series of west-vergent thrusts and folds and associated piggyback basins, resulting in irregular topography of sea floor with alternating sea ridges and troughs. Pliocene-Quaternary strata of the Chinese margin are little deformed by the westward compression induced by the arc-continent collision in the southern Taiwan. The slope profile of the Chinese margin is characterized by a sigmoidal curvature, representing a typical primary depositional setting of the passive margin. Slope canyons occur mainly on the upper slope and cut sea floor, resulting in irregular topography and representing effects of erosion.application/pdf113088 bytesapplication/pdfzh-TW國立臺灣大學海洋研究所台灣聚合地体構造弧陸碰撞前陸沈積南海Taiwanconvergent tectonicsarc-continent collisionforeland sedimentationSouth China Sea[SDGs]SDG14reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/14864/1/932611M002006.pdf