地理科学进展 ›› 2015, Vol. 34 ›› Issue (7): 909-917.doi: 10.18306/dlkxjz.2015.07.012

• 地貌与第四纪 • 上一篇    下一篇

亚热带季风区湖沼流域表生地球化学元素研究——以江西定南大湖为例

魏志强, 钟巍*(), 陈永强, 谭玲玲   

  1. 华南师范大学地理科学学院,广州 510631
  • 收稿日期:2014-11-01 修回日期:2015-04-01 出版日期:2015-07-10 发布日期:2015-07-10
  • 通讯作者: 钟巍 E-mail:dl06@scnu.edu.cn
  • 作者简介:

    作者简介:魏志强(1989-),男,广东梅州人,硕士生,主要从事全球变化与环境信息系统研究,E-mail: 15626457088@163.com

  • 基金资助:
    国家自然科学基金项目(40671189);广东省自然科学基金项目(06025042,031522,2014A0303-13435);教育部霍英东基金项目(91021)

Supergene geochemical elements of swampy basin in the subtropical monsoon region: a case study of Dingnan Dahu in Jiangxi Province

Zhiqiang WEI, Wei ZHONG*(), Yongqiang CHEN, Lingling TAN   

  1. School of Geography Science, South China Normal University, Guangzhou 510631, China
  • Received:2014-11-01 Revised:2015-04-01 Online:2015-07-10 Published:2015-07-10
  • Contact: Wei ZHONG E-mail:dl06@scnu.edu.cn

摘要:

湖沼沉积物地球化学元素对地球气候环境变化敏感性强。本文以江西定南大湖湖沼沉积物地球化学元素为研究对象,使用主成分分析法,并结合总有机碳(TOC)、有机碳同位素(δ13Corg)、中值粒径(Md)、化学蚀变指数(CIA)等相关气候代用指标,以元素组对的形式阐释不同地化元素响应不同气候环境下的地球化学行为和迁移规律。研究结果显示:第一主成分(PC1)包括Al2O3、TiO2、SiO2、Nb、Rb、Ga、Ba、S等元素,曲线变化与CIA相似,指示湖泊流域的化学风化强度,气候暧湿,PC1含量高;第二主成分(PC2)包括Co、Zr、Hf元素,曲线变化与中值粒径较为一致,指示湖泊流域的水动力条件,气候冷干,PC2含量高;第三主成分(PC3)包括Sc、Cu、U、V元素,曲线变化与TOC、δ13Corg含量变化一致。大湖沉积物的物质来源为:在气候暧湿、流域化学风化作用强的条件下,地表径流冲刷流域周边花岗岩风化壳物质并搬运至湖盆沉积,但不排除在冷干时期,风力携带粉尘物质堆积的影响,粉尘物质可能主要源于周边的风化碎屑物。

关键词: 定南大湖, 地化元素, 主成分分析, 气候变化, 沉积物源

Abstract:

Geochemical elements of the lacustrine-swamp sediments are very sensitive to climate change. This study focused on the geochemical elements of the Dingnan Dahu swamp, Jiangxi Province and extracted three main component groups by using the principal component analysis method combined with related climate proxies, such as total organic carbon (TOC), organic carbon isotope (δ13Corg), median grain size (Md) and chemical index of alteration (CIA). Base on these element groups, we interpret how different geochemical elements respond to variant climate conditions and their behavior patterns. The result shows that the first principal component (PC1), includes the elements of Al2O3, TiO2, SiO2, Nb, Rb, Ga, Ba, S, and so on, indicates the weathering intensity of the lake basin; the second principal component (PC2), includes the elements of Co, Zr, and Hf, indicates hydrodynamic conditions of the Dingnan Dahu swamp; and the third principal component (PC3), includes the elements of Sc, Cu, U, and V, is heavily affected by the organic matter of the marshland. The curve of PC1 is similar to CIA, and higher loadings of PC1 suggests a warm and wet climate. The variation trends of PC2 and PC3 are similar to Md and TOC(and δ13Corg), respectively, and the higher loadings of PC2 and PC3 both suggest a cold and dry climate. The origin of this lacustrine deposit was mainly the local weathered products washed by surface runoff under the condition of warm and wet climate and strong chemical weathering. However, during the cold and dry periods, strong winter monsoon might have carried dust from local weathered products and deposited to the basin as well.

Key words: Dingnan Dahu, geochemical elements, principal component analysis, climate change, sedimentary source