新仙女木期黄河晋陕峡谷古风成沙层年代及其物质来源
发布时间：2018-08-25 19:54
【摘要】：通过对黄河晋陕峡谷壶口至龙门段开展广泛细致的野外考察,发现了典型的晚更新世以来黄土—土壤层夹古风成沙层剖面—北桑峪剖面(BSY)。结合不同类型沉积物的野外宏观特征、磁化率、粒度成分、石英颗粒表面特征和地球化学元素的对比分析,确定黄河晋陕峡谷壶口至龙门段BSY剖面中所夹古风成沙层的性质为中沙质细沙,是在干旱多风环境下形成的沙质沉积物。基于光释光(OSL)测年数据,确定其沉积年代为12.5-11.6 ka,记录了黄河中游发生在末次冰消期的极端干旱事件,其与相邻区域沙漠/黄土过渡带中湖沼沉积和风成黄土—古土壤剖面记录的新仙女木事件相对应。该剖面中古风成沙沉积物的物质来源,主要来自黄河晋陕峡谷的古河床相沙层物质。这是因为该河段处于干旱半干旱季风气候区,在新仙女木时期,黄河晋陕峡谷处于极端干冷的环境之中,冬季风强盛、夏季风衰弱,黄河水位下降明显,河漫滩和江心洲将大面积出露,大量的沙物质在风力作用下向岸边输移,成为河谷两侧缓坡台地上古风成沙沉积层出现的主要沙源地。这个研究成果对于进一步揭示黄河中游流域极端干旱事件发生的时间性规律及其与季风气候变化的关系,具有重要的科学意义。
[Abstract]:Through extensive and meticulous field investigation of Hukou to Longmen section of the Jinshan Gorge of the Yellow River, the typical (BSY). Profile of loess, soil layer, paleo-aeolian sand bed and Beisangyu section has been found since the late Pleistocene. Combining with the field macroscopical characteristics, magnetic susceptibility, particle size composition, surface characteristics of quartz particles and geochemical elements of different types of sediments, The properties of the paleolian sand layer in the BSY section of Hukou to Longmen section of the Jinshan Gorge of the Yellow River are determined to be medium sand fine sand and sandy sediment formed in arid and windy environment. Based on the (OSL) dating data, it was determined that the sedimentary age was 12.5-11.6 ka,. The extreme drought events occurred in the last ice extinction period in the middle reaches of the Yellow River were recorded. It corresponds to the neo-fairy events recorded in the adjacent desert / loess transitional zone between the lake-marsh deposits and the aeolian loess paleosol profile. The material source of paleo-aeolian sediment in this section mainly comes from the sand layer of ancient river bed in Jinshan valley of the Yellow River. This is because the reach of the river is in the arid and semi-arid monsoon climate area. During the period of the new fairy tree, the Jinshan Valley of the Yellow River was in an extremely dry and cold environment. The winter monsoon was strong, the summer monsoon was weak, and the water level of the Yellow River had dropped obviously. A large area of floodplain and Jiangxinzhou will be exposed, and a large amount of sand will be transported to the shore under the action of wind force, which will become the main sand source of paleo-eolian sand deposits on the gentle slope platform of both sides of the river valley. This study is of great scientific significance for further revealing the temporal regularity of extreme drought events in the middle reaches of the Yellow River and their relationship with monsoon climate change.
【作者单位】： 西北大学城市与环境学院;西北大学地质系;陕西师范大学旅游与环境学院;西安工程大学环境与化学工程学院;
【基金】：国家自然科学基金项目(41471071,41401602) 中国博士后科学基金项目(2016M59289) 陕西省重点科技创新团队计划(2014KCT-27)~~
【分类号】：P534.63;P931.3
，
本文编号：2203932
[Abstract]:Through extensive and meticulous field investigation of Hukou to Longmen section of the Jinshan Gorge of the Yellow River, the typical (BSY). Profile of loess, soil layer, paleo-aeolian sand bed and Beisangyu section has been found since the late Pleistocene. Combining with the field macroscopical characteristics, magnetic susceptibility, particle size composition, surface characteristics of quartz particles and geochemical elements of different types of sediments, The properties of the paleolian sand layer in the BSY section of Hukou to Longmen section of the Jinshan Gorge of the Yellow River are determined to be medium sand fine sand and sandy sediment formed in arid and windy environment. Based on the (OSL) dating data, it was determined that the sedimentary age was 12.5-11.6 ka,. The extreme drought events occurred in the last ice extinction period in the middle reaches of the Yellow River were recorded. It corresponds to the neo-fairy events recorded in the adjacent desert / loess transitional zone between the lake-marsh deposits and the aeolian loess paleosol profile. The material source of paleo-aeolian sediment in this section mainly comes from the sand layer of ancient river bed in Jinshan valley of the Yellow River. This is because the reach of the river is in the arid and semi-arid monsoon climate area. During the period of the new fairy tree, the Jinshan Valley of the Yellow River was in an extremely dry and cold environment. The winter monsoon was strong, the summer monsoon was weak, and the water level of the Yellow River had dropped obviously. A large area of floodplain and Jiangxinzhou will be exposed, and a large amount of sand will be transported to the shore under the action of wind force, which will become the main sand source of paleo-eolian sand deposits on the gentle slope platform of both sides of the river valley. This study is of great scientific significance for further revealing the temporal regularity of extreme drought events in the middle reaches of the Yellow River and their relationship with monsoon climate change.
【作者单位】： 西北大学城市与环境学院;西北大学地质系;陕西师范大学旅游与环境学院;西安工程大学环境与化学工程学院;
【基金】：国家自然科学基金项目(41471071,41401602) 中国博士后科学基金项目(2016M59289) 陕西省重点科技创新团队计划(2014KCT-27)~~
【分类号】：P534.63;P931.3
，
本文编号：2203932
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