【摘要】 对南海西沙海槽111PC孔沉积物中的硅藻化石研究表明,硅藻以热带、亚热带浮游性种类和近岸性种类为主,可划分出6个硅藻组合带,大体对应于浮游有孔虫氧同位素6个期次。结合有地层对比意义的属种及组合,建立了里斯冰期以来本孔的硅藻生物地层框架。硅藻丰度、属种组合变化指示海区气候经历了冰期-间冰期气候旋回及不稳定性波动。晚玉木冰期硅藻丰度高,冰后期、中玉木冰期次之,里斯冰期至早玉木冰期丰度较低,这与南海西南部不同,与南海东北相似但也不尽相同。里斯冰期至里斯玉木间冰期转换阶段,硅藻属种对气候变暖的反应较快。硅藻属种特征显示中玉木冰期气候为弱暖期,且有早晚两个暖湿阶段。硅藻属种的不连续分布也表明沉积环境在部分时段极不稳定。更多还原

【Abstract】 According to diatom analysis of Core 111PC from the Xisha Trough, South China Sea (SCS), the diatom flora are dominated by tropical-subtropical plankton and coastal species and can be classified to 6 diatom assemblage zones corresponding to the foraminifer oxygen isotope stages, and the diatom biostratigraphy framework is established. Variations of diatom’s abundances and species percentage in the core coupled with the glacial and interglacial cycles and climate instability in this region. Abundances of diatom are higher in the late Wurm glacial stage, and during post-glacial (Holocene) as well as the middle Wurm glacial stage they are medium. While, they are much lower during the Riss glacial stage to early Wurm glacial stage. Diatom abundance character in northwest SCS is different to southwest SCS, and similar to the northeastern SCS. Diatom responds to climate changing abruptly during the transition between the Riss glacial stage to Riss-Wurm interglacial stage. Species characteristics reveal the early and late short warm period present during the middle Wurm glacial stage. The intermittent distribution of some diatom species in the core reflects that the marine environment is extremely unstable in some geological periods.更多还原