班公湖‒怒江缝合带中西段白垩纪放射虫生物地层研究及其对古海洋演化的约束

班公湖-怒江缝合带是拉萨和羌塘地块之间已经消亡的特提斯洋的遗迹，其记录了班公湖-怒江特提斯洋俯冲-消亡和拉萨-羌塘地块碰撞的关键信息。重建该大洋的演化过程，可为研究冈瓦纳古陆的解体和青藏高原的隆升等地球动力学过程提供支撑。然而，相较于邻区的雅鲁藏布江缝合带，该缝合带中白垩纪生物地层的研究仍稍显薄弱。放射虫化石在海洋沉积物中广泛保存，尤其是在缝合带等其他化石不易保存或易遭破坏的构造复杂区，放射虫生物地层的研究在恢复缝合带复杂的地层层序、古海洋盆地演化及海洋古地理等关键问题方面具有得天独厚的优势。本项目拟以班公湖-怒江缝合带中西段白垩纪海相沉积记录为切入点，①通过放射虫生物地层学研究，定量化建立高分辨率生物-年代地层格架；②通过对放射虫生物古地理分区和古生态特征研究，结合含放射虫硅质岩地球化学指标，揭示古海洋演化过程。研究结果有望通过生物年代学的证据对大洋消亡这一地球动力学过程进行约束。

The Bangong-Nujiang suture zone represents the remnants of the Tethyan Ocean and records the transition from Bangong-Nujiang Tethyan oceanic subduction to Lhasa-Qiangtang continental collision. Reconstructing the evolution of the Bangong-Nujiang Tethyan Ocean plays an indispensable role in understanding the linkage between Gondwana dispersion and Tibetan Plateau accretion. Compared to the Yarlung-Zangbo suture zone, however, the Cretaceous biostratigraphic study in the Bangong-Nujiang suture zone is relatively poor. Radiolarian fossils are widely preserved in the marine sediments. In regions with high tectonic intensity, where other diagnostic fossils are absent, radiolarian assemblages play an important role in restoring the stratigraphic sequence of the suture zone, the evolution of the oceanic basin, and the paleogeography of the paleo-ocean. Therefore, this project focuses on the Cretaceous marine sediments in the central and western segments of the Bangong-Nujiang suture zone and intends to establish a high-resolution quantitative bio-chronostratigraphic framework based on radiolarian biostratigraphy. The study of biopaleogeographical zoning and paleoecological characteristics, combined with radiolarian-containing siliceous rock geochemical indicators, will reveal the evolution of the paleo-ocean. The results of this study have the potential to constrain the geodynamic process of ocean demise through biochronological evidence.