摘要
台灣島位於歐亞大陸板塊與菲律賓海板塊的交界帶，晚中新世時因呂宋島弧與歐亞大陸板塊的大陸邊緣碰撞而抬升，在碰撞的過程中，造山帶因抬升剝蝕的沉積物被保存在弧前盆地之中並形成現今海岸山脈的一部分。 本研究利用熱定年對海岸山脈的沉積岩以及現生河砂分析，並結合前人在熱定年以及沉積學上的研究，探討中央山脈的剝蝕狀態，以及海岸山脈沉積岩層的沉積物來源變化。 本研究的熱定年結果顯示在海岸山脈中段1 Ma附近的地層鋯石核飛跡約為3.3 Ma，相同沉積年代的南段地層為6 Ma，而現生河砂在中南兩地區的核飛跡年代皆約為1.5 Ma，顯示在1 Ma以來中央山脈處於加速剝蝕的狀態，中段的磷灰石核飛跡的延遲時間亦顯示加速剝蝕趨勢。而鋯石鈾-鉛年代的結果指出海岸山脈沉積層的年代從蕃薯寮層到八里灣層都有相似的年代群分佈，表示海岸山脈所接收到的沉積物來源相當固定。
並列摘要
Taiwan orogenic belt results from the collision between the Philippine Sea plate and Eurasia plate that results in rapid exhumation of mountain belt since the late Miocene.Taiwan orogenic belt can be divided four NE trending units from west to east: the Coastal Range, the Center Range, the Hsuehshan Range, and the Western Foothills. The Coastal Range is composed of Luzon arc, forearc basin deposit, and the suturezone. The forearc basin deposit is composed of pre- to syn-collision sediments and the provenances come from the eastern Center Range (eastern Eurasia continental margin) and Luzon arc and sedimentation rate increases from ca. 1Ma with 8-11 km/myr. Here we combined with detrital Zircon U-Pbages and fission track ages of forearc basin to study the provenance of forearc basin sediment and exhumation rate of the Center Range. Most of the detrital zircon U-Pb ages of the FanshuliaoFormation are Mesozoic to Proterozoic ages which indicatesof most sedimentcomes from the Eurasia continental margin rather than Luzon arc. Both the Fanshuliao Formation and the Paliwan Formation have similar U-Pb ages spectrum also infers they have similar sources. In center segment of forearc basin the reset age of detrital zircon fission track is ca. 3.3Ma and 1.5 Ma in 1Ma strata and river sand, respectively. In southern segment of the forearc basin the reset detrital zircon fission track ages is ca. 6Ma and 1.5Ma in 1Ma strata and rive sand. Considering decreasing the lag time in forearc basin that indicates the exhumation rate of Center Range increases with time.The lag time of apatite fission track age also shows accelerating the exhumation rate in Center Range. The acceleration of exhumation rate in Center Range is the similar with the increasing the sedimentation rate in forearc basin since ca. 1Ma.