摘要
安徽宣城向阳剖面是我国南方第四纪红土标准剖面,蕴含着丰富的古环境与古气候信息,对其进行常量元素地球化学特征及古气候的研究,对深刻理解该区红土风化成壤强度与古气候演化、充实中国南方第四纪红土的高分辨率研究具有一定意义。本文基于野外地质地貌、岩性调查与加密采样,运用ZSX PrimusIV型X射线荧光光谱仪(XRF),对该剖面进行常量元素测定,并采用地球化学风化参数指标CIA与BA、元素迁移率等分析方法,结合前人的年代数据,探讨了该剖面红土风化特征及古气候意义。研究表明:(1)向阳剖面常量元素以Fe2O3、Al2O3、SiO2为主,具有显著的富硅铝铁化特征,约916 ka以来红土堆积处于相对暖湿的古气候背景下,但是气候总体有向干凉方向变化的趋势;(2)约916 ka以来研究区古气候大致存在7次相对暖湿与相对干凉期的旋回变化;其中,阶段I至阶段II暖湿程度与风化强度较大,气候向暖湿方向发展,阶段III暖湿程度与风化强度均有所降低,阶段IV暖湿程度与风化强度达到最大,是最稳定的时期,阶段V至阶段VII气候一直向干凉方向变化;(3)在6.2 m(约534 ka前)以下部分,红土成土沉积动力强度较大,干湿变化比较强烈,沉积环境不稳定,而此后红土成土沉积动力减弱,沉积环境相对稳定。
The Xiangyang section in Xuancheng, Anhui Province is a standard section of the Quaternary red clay in southern China, which contains rich information on past paleoenvironment and paleoclimate. The study on the major elements, geochemical characteristics and paleoclimate of Xingyang section has great significance to the insights into the red clay weathering intensity and paleoclimate evolution across the region, and also the investigation about the high-resolution of quaternary red clay in South China. Based on field geological and geomorphic investigation and density-increased sampling, the ZSX Primus IV X-ray fluorescence spectrometer(XRF) was used to measure the major elements of this section. Moreover, combining with the chronological data of predecessors, the weathering characteristics and paleoclimatic significance of the red clay in this section were discussed by using combined methods of the geochemical weathering parameters(CIA and BA) and element mobility. The research results showed that:(1) The main elements of xiangyang section are Fe2O3, Al2O3 and SiO2, which have significant characteristics of ferro-silicon-aluminium. Since approximately 916 ka ago, the accumulation of the red clay was in a relatively warm and wet paleoclimate, but the climate generally changed towards the direction of dry and cool since then.(2) During the past 916 ka, the paleoclimate in the Xiangyang section had roughly 7 cycle changes of relative warm and wet periods and relative cool and dry periods. From stage I to stage II, the warm-wet degree and weathering intensity were relatively strong, and the paleoclimate developed towards the direction of warm and wet. In stageIII, both the warm-wet degree and weathering intensity decreased. In stage IV, they reached the maximum, which was the most stable period. From stage V to stage VII, the paleoclimate had a tendency of dry and cool. In stage VII, the degree of the warm-wet and weathering intensity reached the minimum;(3) Under 6.2 m(about 534 ka ago), the sedimentary dynamic str
作者
李文慧
胡春生
田景梅
曹乐
LI Wenhui;HU Chunsheng;TIAN Jingmei;CAO Le(School of Geography and Tourism,Anhui Normal University,Wuhu 241000,Anhui,China;Anhui Key Laboratory of Earth Surface Processes and Regional Response in Yangtze-Huaihe River Basin,Wuhu 241000,Anhui,China)
出处
《山地学报》
CSCD
北大核心
2020年第3期371-383,共13页
Mountain Research
基金
安徽省高校优秀青年人才支持计划项目(gxyqZD2018014)
安徽师范大学博士科研启动基金(2018 XJJ43)。
关键词
宣城向阳剖面
第四纪红土
常量元素
地球化学风化参数
古气候变化
Xiangyang section in Xuancheng
quaternary red clay
major elements
geochemical weathering parameters
paleoclimate changes
