【摘要】 对长江三峡大宁河流域双堰塘剖面的粒度、磁化率和氧化物进行了综合分析 ,揭示了该区 30 0 0 a来的沉积环境变化 ,并对全新世第 1寒冷期的风尘堆积作了初步探讨。该区 30 0 0 a来的风尘堆积是在全新世第 1寒冷期 (10 0 0～ 85 0 BC) ,即是亚北方期又是新冰期时形成的。而此寒冷期又存在次一级的气候波动。风尘堆积下层是在干凉气候下形成的原始风尘堆积 ,而上层气候趋于冷湿 ,流水作用增强 ,原始风尘堆积被流水搬运 ,在此形成次生黄土。由于所受水动力条件和风化程度的不同 ,本区风尘堆积与长江下游地区的风尘堆积以及北方黄土之间存在着明显的差异之处更多还原

【Abstract】 Synthetic analyses of grain size,susceptibility and oxide of Shuangyantang profile in Daning valley,the Three Gorges of the Yangtze River reveal sedimentary environment changes and eolian deposits since 3 kaBP ago in this area.There was Holocene warm humid climate in the region,but eolian deposits are formed since 3 000 a ago during the first cold period of the Holocene(1000～850 B.C.)in this area,that was the Subboreal Phase or Neoglaciation Age of the Holocene.During this stage,there were short climatic oscillations according to susceptibility and oxide research.The lower layer of the eolian deposits was primary dust accumulation in cold arid climate,but the upper loess layer was formed in cool humid climate.Strong running water transported primary eolian deposit to form secondary loess.Different water powers and weathering levels made great differences between eolian deposits in this area and those in the Yangtze River and North Loess of the Pleistocene.更多还原