晚冰期以来大柴旦盐湖沉积记录的古气候演变及其尘暴事件

摘要

选择大柴旦盐湖DCD03沉积剖面柱硼镁石矿层下伏土黄色淤泥质粉砂层为研究对象,基于AMS 14C年代学、岩性地层学、矿物学以及地球化学等研究方法,旨在探讨土黄色湖相淤泥质粉砂沉积记录的尘暴事件,以及重建晚冰期以来西风环流显著影响区的水文气候变化.研究结果表明,DCD03沉积剖面的淤泥质粉砂样品粒度频率曲线呈现为双峰态,主峰(均值10μm)反映了河流作用携带入湖的细粒组分,次峰(＞32μm)则反映了风力作用以及河流作用等携带入湖的粗粉砂粒组分.大于64μm的砂砾组分可能代表外源风尘物质的输入,由尘暴天气携带入湖.大柴旦地区晚冰期以来依次出现了博令和阿勒罗德暖期(12.94～12.17 cal.ka BP)、新仙女木冷期(12.17～11.37 cal.ka BP)、不稳定的早全新世气候(11.37～8.64 cal.ka BP)以及趋于偏冷干的中全新世早期(8.64～7.39 cal.ka BP).%The paper focused on the study of muddy silt from sediment profile DCD03 of Da Qaidam Salt Lake, based on AMS 14C chronologic, lithostratigraphic, mineralogical and geochemical methods, aimed to discuss the dust storm event recorded by earthy yellow muddy silt, and reconstruct the hydro-climate changes of Da Qaidam region since Late Glacial period.The results showed that the grain-size distribution curve appeared double kurtosis, the main peak (10 μm) reflected fine-grained component by fluvial action, and the secondary peak (＞32 μm) reflected coarse-grained component by aeolian and fluvial action.The gravel component (＞64 μm) may record the dust storm event.Da Qaidam region underwent B?lling/Aller?d warm period (12.94-12.17 cal.ka BP), Younger Dryas cold period (12.17-11.37 cal.ka BP), unstable early Holocene period (11.37-8.64 cal.ka BP) and relatively cold-dry early mid-Holocene period (8.64-7.39 cal.ka BP) in sequence since Late Glacial period.