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干旱区地理 ›› 2014, Vol. 37 ›› Issue (6): 1191-1198.

• 地表过程研究 • 上一篇    下一篇

汉江上游弥陀寺黄土-古土壤序列的化学风化特征及其环境意义

王学佳，庞奖励，黄春长，周亚利，卞鸿雁，张玉柱，高鹏坤   

  1. （陕西师范大学旅游与环境学院，陕西西安710062）
  • 收稿日期:2013-12-15 修回日期:2014-03-03 出版日期:2014-11-25
  • 通讯作者: 庞奖励（1963-）. Email:jlpang@snnu.edu.cn
  • 作者简介:王学佳，女（1988-），山西朔州人，硕士，研究方向为资源开发与环境演变. Email：wangxuejia5@163.com
  • 基金资助:

    国家自然科学基金项目（41271108；41030637；41371029）；中央高校基本科研费（GK201301003）

Chemical weathering characteristics of Mituosi’s Loess-palaeosol sequence in the upper Hanjiang River Valley and its environmental significance

WANG Xue-jia，PANG Jiang-li，HUANG Chun-chang，ZHOU Ya-li，BIAN Hong-yan，ZHANG Yu-zhu，GAO Peng-kun   

  1. （College of Tourism and Environment, Shaanxi Normal University, Xi'an 710062, Shaanxi, China）
  • Received:2013-12-15 Revised:2014-03-03 Online:2014-11-25

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摘要： 对汉江上游谷地弥陀寺黄土剖面的地层序列和常量元素进行了研究，用光释光测年法（OSL）对地层进行了断代。结果显示：剖面中Na2O、MgO、CaO 表现淋失，Fe2O3、K2O 和Al2O3则相对富集，其中在古土壤中这些元素表现淋失或富集程度更为强烈；剖面具有斜长石风化为主的初级化学风化程度，以Ca、Na 流失严重为特征；从马兰黄土L1→古土壤S0→全新世黄土L0，风化由弱变强再变弱。这些信息揭示了汉江上游地区晚更新世以来的环境尤其是气候的变化规律：18 000～11 500 a BP 气候以干冷为主，进入全新世后逐渐转暖，8 500～3 100 a BP 为全新世大暖期，气候温湿，3 100 a BP 后气候又转凉，呈现出由“冷干→转暖→暖湿→干凉”的演变过程，同时弥陀寺黄土对6 000～5 000 a BP 期间发生的气候波动冷事件也有记录响应。

关键词: 黄土, 化学风化, 气候变化, 弥陀寺, 汉江上游

Abstract: Stratigraphic sequence and constant elements were studied in Mituosi’s loess profile，Yun County，Hubei Province，China. And optically stimulated luminescence（OSL）was carried out on dating the loess sediments. The aim is to discuss the chemical weathering characteristics and the palaeoenvironmental change based on comprehensive approaches，such as Chemical Index of Alteration（CIA），A-CN-K diagram，Na/K and Fe/Mg. Results showed that the major composition of Mituosi’s loess section was made up with SiO2 and Al2O3. Na2O，MgO，CaO were performed leaching in the profile，while Fe2O3，K2O and Al2O3 were enriched. Moreover these elements behaved leaching or enriching more intensely in the palaeosol. The leaching of Na，Mg and Ca is due to the weathering of plagioclase and pyroxene. While Fe and Al’s relative enrichment is because of leaching of other elements. The K enrichment is likely to be its ion adsorpted by relevant clays. These elements’geochemical variations could reflect the pedogenic modification of loess in Mituosi. The CIA（65.41）and A-CN-K diagram showed the profile experienced the primary chemical weathering processes in which Ca，Na loss was serious，but almost no leaching of K. And it was transited to middle stage of chemical weathering. The weathering products mainly are montmorillonite and illite. It has not reac- hed kaolinite and gibbsite-based degree of weathering .The CIA，Na/K and Fe/Mg’s curves all indicated the weathering was from weak to strong degrees and then weakened，which from Malan loess to palaeosol then to Holoncene loess. This information revealed the palaeoenvironment，especially the palaeoclimate change since the late Pleistocene. The climate was characterized by cold and dry climate at about the late Pleistocene 18 000-11 500 a BP；Then that came to the Holocene，it was becoming warm. And the Holocene warm period was during 8 500-3 100 a BP，after about 3 100 a BP. The climate turned cool again. All above indicated the climate was“cold-dry→warm→ warm-wet→cool-dry”. Meanwhile the climatic cold fluctuation events at about 6 000-5 000 a BP. have been recorded and responded by Mituosi’s loess.

Key words: loess, chemical weathering, climate change, Mituosi, the upper reaches of the Hanjiang River

中图分类号: 

  • S153