珠江口外大陆坡钻孔揭示的MIS8期以来陆缘植被演变及海-陆变化周期性特征

The variation of vegetation is crucial of the global natural environmental evolution, and research of that is significant to understand the human activities as also explore climate-vegetation response. The northeastern continental slope of SCS nearly the south-east continental shelf and Pearl River mouth basin have richly deposited deep ocean pollen sediments, which detailed record glacial/interglacial cycles of continent and ocean environment change. This study has planned to carry out the pollen analysis combining with the oxygen isotope stratigraphy and AMS 14C dating results of a long core from the northern slope nearby the Pear River estuary, to reveal the detail of terrestrial vegetation change and ocean-continental cycles. As a result, The core pollen results and the ocean -continental surface pollen distribution as well as the modern original vegetation has been analyzed to detect the glacial pollen source and variation. In addition, the model of shoreline migration and sea level change between glacial and interglacial can set up by core pollen concentration comparing with the surface pollen concentration of SCS. Moreover, the vegetation change in South China and continental shelf during glacial periods can reconstruct according with the detail information of pollen analysis since MIS8 from ocean and continent, revealing continental slope depositional environment and sea-level change as well as global climate evolution.

植被演化是地球自然环境变率的重要过程，研究植被演替对深入认识人类活动对地球环境的影响以及探索植被-气候响应具有重大意义；南海北部陆坡靠近东南部大陆架以及珠江口流域，拥有丰富的深海孢粉沉积，详细记录了冰期-间冰期旋回的陆地-海洋生态环境变迁。本项申请拟利用对珠江口外的北部陆坡海域所获取的钻孔开展长尺度的孢粉分析，结合氧同位素地层和AMS14C测年结果，探讨MIS8期以来孢粉记录的陆源植被演变以及海陆变化周期性特征。通过陆坡钻孔孢粉、海陆现代孢粉分布以及陆地植被进行类比来追踪珠江口外北部陆坡的冰期孢粉物质来源及其变化；对钻孔花粉浓度与海洋表层花粉浓度进行对比分析，建立冰期/间冰期花粉沉积浓度与海岸线迁移，海平面下降关系的模型；根据MIS8期以来孢粉主要特征，进行海陆孢粉对比研究，定量重建华南地区和大陆架冰期植被变化过程，进一步深入认识陆坡沉积环境与海平面变化、全球气候演变的关系。

南海北部陆坡靠近中国大陆架沿岸以及珠江口流域，拥有丰富的深海孢粉沉积，详细记录了冰期-间冰期旋回的陆地-海洋生态环境变迁。孢粉作为研究过去植被演化的有效指标，是深入认识冰期与间冰期海岸带及陆架植被环境变迁的重要手段之一。本研究通过对珠江口外的陆坡海域所获取的钻孔开展长尺度的孢粉分析研究，结合氧同位地层和AMS14C测年结果，揭示了冰期以来孢粉记录的陆源植被演变以及海陆变化周期性特征。本研究主要得出以下结果：一是对珠江口外大陆坡钻孔中孢粉组合特征所指示的环境意义有了充分认识。二是对南海东北部的表层孢粉传播有了更加系统的认识，充分理解和掌握了南海东北部陆源物质的传输模式以及南海海洋孢粉所指示的植被和环境意义。三是对珠江口岸的陆地钻孔孢粉所指示的环境意义有了充分的认识，得出海侵期和全新世晚期的植被组合面貌，对研究珠江口外陆坡钻孔的孢粉沉积具有很好的指导意义。四是对南海东北部陆架区域的全新世钻孔进行了孢粉分析，判别了晚全新世孢粉物质来源的改变，以及对沿岸沉积环境演变的指示意义。

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