南海扩张过程及海陆变迁:菲律宾巴拉望-民都洛陆块地层沉积记录

南海南、北共轭陆缘盆地的对比研究是深入了解南海扩张过程的重要途径。但由于历史因素，目前我国对南海南缘盆地构造-沉积演化研究还非常薄弱，极大地限制了对南海扩张及海陆变迁等基础地质问题的整体认识。由于南海洋壳俯冲，巴拉望-民都洛陆块与菲律宾活动带碰撞造山，沉积于巴拉望-民都洛陆块的始新世-中新世海相层序得以完整出露，成为唯一可以直接对南海南缘盆地沉积层序进行详细研究的陆上窗口。本项目以海陆结合的研究思路，在对巴拉望-民都洛陆块的沉积层序、碎屑组成及生物化石等进行系统分析的基础上，对关键层位进行详细的地球化学、碎屑锆石U-Pb年龄谱及Hf同位素分析，建立巴拉望-民都洛新生代地层格架、示踪地层沉积物的来源及时空演化。通过与南海南、北缘盆地已有成果的对比，深入探讨：(1)南海扩张与南、北缘盆地演化的关系；(2)南海扩张前(始新世-早渐新世)古地理格局；(3)渐新世/中新世构造-沉积事件的整体响应。

The surface uplift of the Tibetan Plateau and the onset of seafloor spreading of the South China Sea have had a remarkable influence on the tectonism, landforms, drainage systems and climate in this area during the Cenozoic. When and how, however, the changes happened remain debated. The spreading history of the South China Sea, which is still disputed, is mainly based on the comparison of magnetic anomalies lineaments. The southern South China Sea and its relevant research are of great importance for understanding seafloor spreading of the South China Sea and paleogeographical environment. However because of few seismic profiles and exploration wells we know a little about the tectonic and sedimentary evolution of the basins in the southern South China Sea. The relationship of the two conjugate continental margins are unclear and therefore the tectonic evolution history of the South China Sea is not well constrained. The Eocene-Miocene marine sequences in Palawan-Mindoro, Philippines were exposed by eastward subduction of the South China Sea oceanic lithosphere beneath the Philippine Sea Plate since the Middle Miocene and following arc-continent collision. Therefore, Palawan-Mindoro Island provides one of the best geological windows looking into the detailed geological information about the rifting event, stratigraphy, sedimentology, paleoclimate and paleogeography in the southern margin of the South China Sea. Petrographic and marine micropalentological analysis is applied in this study to the Eocene-Miocene sequences in the Palawan-Mindoro, Philippines to constrain the provenance and sedimentation. In addition, we also determine detrital zircon U-Pb geochronology and Hf isotopic values to test if they were derived from the SE China mainland or southwestern provenance (Indochina-Sunda Shelf and possibly northwestern Borneo). In particular we address：(1) the relationship between the basins in the conjugate continental margins and seafloor spreading of the South China Sea; (2) the provenance and its implication to paleogeographical evolution; (3) the Oligocene-Miocene regional transition of tectonic and landform framework.