【摘要】：通過對黃河晉陜峽谷壺口至龍門段開展廣泛細(xì)致的野外考察,發(fā)現(xiàn)了典型的晚更新世以來黃土—土壤層夾古風(fēng)成沙層剖面—北桑峪剖面(BSY)。結(jié)合不同類型沉積物的野外宏觀特征、磁化率、粒度成分、石英顆粒表面特征和地球化學(xué)元素的對比分析,確定黃河晉陜峽谷壺口至龍門段BSY剖面中所夾古風(fēng)成沙層的性質(zhì)為中沙質(zhì)細(xì)沙,是在干旱多風(fēng)環(huán)境下形成的沙質(zhì)沉積物�；诠忉尮�(OSL)測年數(shù)據(jù),確定其沉積年代為12.5-11.6 ka,記錄了黃河中游發(fā)生在末次冰消期的極端干旱事件,其與相鄰區(qū)域沙漠/黃土過渡帶中湖沼沉積和風(fēng)成黃土—古土壤剖面記錄的新仙女木事件相對應(yīng)。該剖面中古風(fēng)成沙沉積物的物質(zhì)來源,主要來自黃河晉陜峽谷的古河床相沙層物質(zhì)。這是因?yàn)樵摵佣翁幱诟珊蛋敫珊导撅L(fēng)氣候區(qū),在新仙女木時(shí)期,黃河晉陜峽谷處于極端干冷的環(huán)境之中,冬季風(fēng)強(qiáng)盛、夏季風(fēng)衰弱,黃河水位下降明顯,河漫灘和江心洲將大面積出露,大量的沙物質(zhì)在風(fēng)力作用下向岸邊輸移,成為河谷兩側(cè)緩坡臺地上古風(fēng)成沙沉積層出現(xiàn)的主要沙源地。這個(gè)研究成果對于進(jìn)一步揭示黃河中游流域極端干旱事件發(fā)生的時(shí)間性規(guī)律及其與季風(fēng)氣候變化的關(guān)系,具有重要的科學(xué)意義。
[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.
【作者單位】： 西北大學(xué)城市與環(huán)境學(xué)院;西北大學(xué)地質(zhì)系;陜西師范大學(xué)旅游與環(huán)境學(xué)院;西安工程大學(xué)環(huán)境與化學(xué)工程學(xué)院;
【基金】：國家自然科學(xué)基金項(xiàng)目(41471071,41401602) 中國博士后科學(xué)基金項(xiàng)目(2016M59289) 陜西省重點(diǎn)科技創(chuàng)新團(tuán)隊(duì)計(jì)劃(2014KCT-27)~~
【分類號】：P534.63;P931.3
，

本文編號：2203932