| 摘要: | 探討地體架構和地質演化的重要資訊就是了解研究區域內的地殼構造，尤其是對地體構造相對複雜的歐亞大陸東南邊緣的台灣造山帶地區，及其鄰近的區域。本研究結合了來自TAIGER (TAiwan Integrated GEodynamic Research) 計畫和ATSEE (Across Taiwan Strait Explosion Experiment) 計畫資料庫的資料，藉以解析中國大陸東南地區從武夷-雲開造山帶至台灣造山帶，跨越海陸交界的深部地殼地震剖面。
在結果的速度模型中，共有三個剖面被解析出來，最長的剖面可以達到850 km。與二維或三維速度層析法的初達波走時逆推不同的是，本研究不僅使用初達的折射波，同時也使用晚到的反射波訊號 (包含Pg、Pn、PcP和PmP)來進行走時模擬，以求得地殼構造與反射層邊界。在模擬過程中，共選取了40個主動性震源、2個天然地震和將近1,950個測站所產生的訊號，使得從北、中、南三條東西向的剖面上約有15,612個震波到時被擷取出來使用。
利用這些資料，本研究提出了從古生代開始福建中部地區中生代張裂盆地的閉合構造、中生代福建東南沿海由於南中國海擴張所造成的張裂構造和到目前仍在作用中的台灣造山帶碰撞構造的地球物理證據。根據結果可以整理出莫荷面的形貌大致如下所述：在福建西部約為30 km深，向東至福建中部增厚到約35 km深，至台灣海峽則減薄到約28 km深，進入台灣造山帶則又增厚到約42 km深，最後，往東至太平洋西部則又再次減薄到約10 km深。
;Knowledge of the crustal structure is important for understanding the tectonic framework and geological evolution of Taiwan orogeny and its adjacent areas in the southeastern Eurasian plate. In this study, we integrated the datasets from the TAIGER (TAiwan Integrated GEodynamic Research) and ATSEE (Across Taiwan Strait Explosion Experiment) projects to resolve onshore-offshore deep crustal seismic profiles from the Wuyi-Yunkai orogen to the Taiwan orogen in southeastern China.
Three seismic profiles were resolved, and the longest profile was 850 km. Unlike 2D and 3D first arrival travel-time tomography from previous studies, we used both refracted and reflected phases (Pg, Pn, PcP, and PmP) to model the crustal structures and the crustal reflectors. In total, data from 40 shots, 2 earthquakes, and approximately 1,950 stations were used; 15,612 arrivals were selected among three transects.
By using these data, we determined the complex crustal evolution since the Paleozoic era, involving the closed Paleozoic rift basin in central Fujian, the Cenozoic extension due to the South China Sea opening beneath the coastline of southern Fujian, and the on-going collision of the Taiwan orogen. The shape of the Moho, which also reflects the crustal evolution, can be summarized as follows: ~30 km deep to the west of Fujian, deepening toward central Fujian (~35 km), becoming shallower toward the Taiwan Strait (~28 km), deepening again toward the mountain belt of Taiwan (~42 km), and becoming shallower toward the Pacific Ocean (~10 km). |
