首页|玛曲谷地晚全新世风成黄土化学风化程度与气候变化

玛曲谷地晚全新世风成黄土化学风化程度与气候变化

扫码查看
本文以若尔盖盆地玛曲黄河一级阶地覆盖的老桥西(LQX)剖面为研究对象,对其粒度、磁化率、元素含量及地球化学参数进行研究,用光释光方法进行测年断代,在构建剖面地层年代框架基础上,试图揭示晚全新世以来风成黄土的化学风化特征及记录的环境变化特征.结果显示:①LQX剖面地层年代框架为:河流相砂层FS(>3.0ka)→风沙层AS(3.0~2.5 ka)→下部黄土层L02(2.5~2.3 ka)→ 土壤层MS1(2.3~1.6 ka)→上部黄土层L01(1.6~0.4 ka)→表土层 MS0(0.4 ka~至今).②LQX剖面处于以斜长石风化为主的低等化学风化阶段,且不同地层单元风化成壤强度顺序为L02较弱→MS1最强→L01略有减弱→MS.增强.③玛曲谷地晚全新世以来经历了冷干期(3.0~2.5 ka)—凉干期(2.5~2.3 ka)—暖湿期(2.3~1.6 ka)—冷干期(1.6~0.4 ka)—暖湿期(0.4 ka~至今)的气候变化,与青藏高原及其他地区古气候信息记录吻合度较高.
Chemical weathering degree of the Late Holocene aeolian loess and climate change in Maqu Valley
After extensive and detailed field investigation in the Zoige Basin,a Late Holocene aeolian loess-paleosol section at Laoqiaoxi(LQX)site on the first river terrace(T1)of the Yellow River in the Maqu reach was selected for research.The grain-size distribution,magnetic susceptibility,the distribution characteristics of major elements and the geochemical behavior of the loess surface(such as CIA,alkali degradation coefficient,leaching coefficient,residual coefficient,calcium magnesium ratio,sodium potassium ratio,rubidium strontium ratio,etc.)are studied.Based on the stratigraphic-chronological framework by using OSL dating of aeolian loess in the first order terrace of the Yellow River,this paper attempts to reveal the characteristics of chemical weathering processes of aeolian loess and recorded environmental changes since the Late Holocene.The results showed that:(1)LQX section was formed in the Late Holocene,and its stratigraphic-chronological framework is:Fluvial sand(FS,>3.0 ka)→Aeolian sand(AS,3.0-2.5 ka)→ Lower loess(L02,2.5-2.3 ka)→Lower soil(MS1,2.3-1.6 ka)→ Upper loess(L01,1.6-0.4 ka)→ Surface soil(MS0,0.4 ka-present).(2)LQX profile is in the lower chemical weathering stage dominated by the weathering of plagioclase,and the order of intensity of weathering and pedogenesis in different stratigraphic units is:AS is the weakest layer → L02 gets weaker →MS1 is the strongest layer → L01 slightly gets weaker → MS0 gets stronger.(3)Since the Late Holocene,the Maqu Valley has experienced the climatic changes:cold and dry period(3.0-2.5 ka),cool and dry period(2.5-2.3 ka),warm and wet period(2.3-1.6 ka),cold and dry period(1.6-0.4 ka),warm and wet period(0.4 ka-present),which is in good agreement with the paleoclimatic information records of the Tibetan Plateau and other areas.This findings provide the first evidence for constructing the trajectory of climate evolution in the region since the Late Holocene,and further enrich the paleoclimate research content in the northeastern Tibetan Plateau.

the first river terrace of the Yellow Rivermajor elementsLate Holoceneclimate changeLQX profile

王忻宇、庞奖励、黄春长、周亚利、查小春、李瑜琴、赵晓康、翟颖、孙雪晴

展开 >

陕西师范大学地理科学与旅游学院,西安 710119

黄河一级阶地 常量元素 晚全新世 气候变化 LQX剖面

国家自然科学基金项目国家自然科学基金项目国家自然科学基金项目国家自然科学基金项目

42271046422774494197111642071112

2024

地理研究
中国科学院地理科学与资源研究所

地理研究

CSTPCDCSSCICHSSCD北大核心
影响因子:2.214
ISSN:1000-0585
年,卷(期):2024.43(7)