汉江上游黄土堆积有机质稳定碳同位素揭示的古人类生存环境

Abundant lithic artifacts of hominines lived in early to late Pleistocene have been discovered from loess deposits along Upper Hanjiang River, showing this region is an very important place for understanding the early human behaviors and evolution. To study the deposit record is a key to know the vegetation and climate when the hominin lived in this region. But, this work is largely not undertaken. In the Chinese Loess Plateau which in the north of Qinling Mountains, the stable carbon isotopic composition of organic matter (δ13C) in loess deposit has been widely used in the paleovegetation and paloeclimatic reconstruction. While in the south of Qinling Mountains, the paleovegetaion and paleoclimate implications of the δ13C may be different from that in the North. In this project, we will sampling five representative loess sections in the Upper Hanjiang River to systematically survey the loess organic δ13C and the vegetation changes. On the basis of relationship between the modern soil organic matter δ13C and the vegetation, we will reveal the paleovegetation and apleoclimatic implications of the loess δ13C; combined with investigations of pollen, magnetic susceptibility we will reconstruct the paleovegetation and paleoenvironmental changes since the early Pleistocene and to reconstruct the climate and vegetation when the hominines lived there, this would provide new observations to understand the subtropical ecological environmental changes and its impact on hominines activities in Pleistocene in the south of Qinling Mountains.

在汉江上游地区的黄土沉积中已经发现了大量更新世古人类遗留的旧石器制品。对汉江上游黄土-环境记录的深入研究，有助于理解更新世人类活动与环境变化之间的关系。在秦岭以北的黄土高原，黄土有机质稳定碳同位素组成（δ13C）已经被广泛应用于古土壤形成时期的植被和气候重建。而在秦岭以南的黄土沉积区，由于气候带和植被类型的变化，黄土有机质δ13C所代表的植被和气候意义可能不同。本项目拟选取秦岭南麓汉江上游的5个代表性黄土剖面，全面测试黄土有机质δ13C。在认识现代土壤有机碳同位素与植被关系的基础上，揭示汉江上游黄土地层有机质δ13C 的植被意义。结合孢粉、磁化率等环境指标分析，建立早更新世以来的环境变化序列，重建古人类活动时的气候和植被状况，为研究更新世我国北亚热带地区生态环境变化及其对人类活动的影响提供科学依据。

汉江上游及其周边的山间盆地黄土沉积中已经发现了大量更新世古人类遗留的旧石器制品。对这些地区的黄土-环境记录的深入研究，有助于理解更新世人类活动与环境变化之间的关系。本项目取秦岭南麓汉江上游的龙岗寺、刘湾、上百川、龙牙洞、张豁口等5个代表性黄土剖面，全面测试黄土有机质δ13C及其它环境指标。并在现代土壤有机碳同位素与植被关系的基础上，揭示汉江上游黄土地层有机质δ13C 的植被意义。研究表明，汉江上游的秦岭山间盆地和河流阶地部位在更新世以来植被为以C3和C4混合的草地植被和C3为主的林地植被呈斑块状镶嵌结构。植被的多样性为古人类生存提供了丰富的生存资源。东秦岭地区在中更新世可能作为古人类生存的避难所，是人类在间冰期向北方扩散和迁移的源区之一。为认识东亚地区如人类生存与环境，尤其是植被变化之间的关系提供了依据。