高校地质学报2017，Vol.23Issue(4)：750-758,9.DOI:10.16108/j.issn1006-7493.2017050
末次冰期晚期半干旱环境下黄河阶地上的河流与风沙沉积交互过程
Aeolian-fluvial Interplay History Recorded by Sediment Sequences from Huanghe Terrace in Semi-arid Environment During the Late Stage of Last Glacial Period
摘要
Abstract
The interactions of fluvial and Aeolian processes are a pronounced feature in dry land environments, which can significantly change Earth surface morphology. The interactions of fluvial and Aeolian processes are common in the Lanzhou-Yinchuan reach of Huanghe river catchment at present, but it is rarely reported in the geological time. Here, we analysis the sedimentology including grain size distribution of a sediment sequence on the T2 terrace of the Huanghe River in this area. Aeolian sand dunes (2-3.8 m thickness) situated between fluvial coarse sands and floodplain silts are distinguished, which show mass structure, and mainly composed of well sorted very fine sand. The poor sorting laminar silt mixed with clay and very fine silt covers these dunes. We consider this sediment unit (laminar silt) as floodplain sediment including some aeolian dust input, settling from static water. The grain size of the aeolian dune is slightly smaller than that of the underlying horizontal fluvial sand. Both of the amounts of the coarse and fine component in the sand dunes are less than that in the underlying fluvial sand. These may indicate that the aeolian sand dunes in this region are built through the wind eroding, sorting, carrying the underlying fluvial sand and accumulating in situ. The elemental compositions of the aeolian sand dunes are consistent with the underlying fluvial sand and different from the sandy loess in this area. This also indicates that the source of the dunes on the terrace is the fluvial sand below the dunes. The OSL ages show that the aeolian dunes were deposited during 21～16 ka, and the covering floodplain silts deposited during 14～13 ka. The correlation of the deposit of dunes with climate change records in this area show the sand dunes were built during the period of strong winter monsoon with cold and dry climate during the Last Glacial Maximum (LGM). And the dunes were covered by floodloam later, when the period of strong summer monsoon with warm and wet climate during the last deglaciation. The sediment sequence composed by fluvial gravel, sand, aeolian dune, floodloam on the second terrace of the Huanghe river in this area show the interactions of fluvial and Aeolian process as a response to the climate and environment changes since LGM in this semi-arid environments.关键词
风成沙丘/河漫滩/末次盛冰期/河流-风沙交互沉积/气候变化Key words
aeolian sand dunes/floodplain deposit/Last Glacial Maximum/aeolian-fluvial interaction/climate change分类
天文与地球科学引用本文复制引用
马俊飞,王先彦,弋双文,戴岩,刘全玉,鹿化煜..末次冰期晚期半干旱环境下黄河阶地上的河流与风沙沉积交互过程[J].高校地质学报,2017,23(4):750-758,9.基金项目
国家自然科学基金项目(41522101)资助 （41522101）
