11.5kaBP以来尕海沉积物氧化物地球化学特征及其环境意义

Geochemical Composition of Sediment in Gahai Lake Since 11.5 ka BP and Its Environmental Implication

通过对柴达木盆地尕海DG03孔沉积序列的年代学测定和沉积物分析,选取对气候环境较为敏感的SiO2,Al2O3,TiO2,Fe2O3,MgO,CaO,K2O,Na2O等作为环境代用指标,分析了尕海地区11.5kaBP以来的气候环境变化。研究表明尕海地区在11.5kaBP以来存在4个明显的气候变化期:晚冰期晚期(11.5～10.16kaBP)的气候波动较大,其中11.5～11.16kaBP是暖干气候;11.16～10.16kaBP,气候冷干,可能是新仙女木事件的反映;全新世早期(10.16～7.83kaBP)气候转暖,有短期极干冷事件的发生;中全新世适宜期(7.83～4.73kaBP),气候温暖湿润;4.73kaBP以来的全新世晚期,气候环境明显恶化,期间出现气候暖湿与干冷的多次波动变化。

On the basis of the new time scale and the analysis of oxide of Core DG03 samples from Gahai Lake in Qaidam Basin, this paper employs SiO2, Al2O3, TiO2, Fe2O3, MgO, CaO, K2O, Na2O and their ratios, which are sensitive to environmental changes, to reconstruct the palaeoenvironmental changes since 11.5 kaBP in Gahai Lake. The results show that there are four distinct climate changing periods in Gahai Lake Area since 11.5 kaBP. At the early stage of the Late Deglaciation, the climate was warm and a little bit dry in 11.5-11.16 kaBP, it soon turned to be extremely cold and dry in 11.16 - 10.16 kaBP, this dramatic changes should be correlated to the Younger Dryas events; When entering into the Holocene period, it was turned warm with some occurrence of short period of cold and dry events in 10.16-7.83kaBP; During the Mid-Holocene period （7.83 -4.73kaBP）its climate was warm and wet, which was the best climatic stage since the Late Deglaciation period. The Late Holocene period （4.73 -0 kaBP） was in the deterioration of climate which was cold and very arid.