摘要
对汉江上游谷地归仙河口剖面的常量元素分布进行研究,结果显示：归仙河口剖面风成黄土的化学成分以SiO2、Al2O3和Fe2 O3为主,Ca、Na、Mg、Si相对于K表现为迁移淋失,Fe、Al相对富集,元素的活动性及迁移序列为Ca＞N a＞ Mg＞ Si＞ K＞ Al＞ Fe,Ca、Na、K的迁移特征说明其达到中等风化阶段.化学蚀变指数、K2O/Na2 O、SiO2/Al2O3、（CaO＋K2O＋Na2 O）/Al2O3和（Al2O3 ＋ Fe2O3）/（MgO＋ CaO＋ Na2O）等地球化学参数,说明古土壤S0形成时期的化学风化最强烈,黄土L1、Lt和L0形成时期的风化作用相对较弱;揭示汉江一级阶地抬升（18.0 ka B.P.前后）以来气候干冷,11.5 kaB.P.开始气候转向暖湿,8.5 kaB.P.开始气候最为暖湿,3.0 kaB.P.开始气候骤然恶化;并记录到4次洪水事件,分别发生在12.5～12.4 kaB.P.、7.5～7.0 ka B.P.、3.1～3.0ka B.P.和1.0～0.9 ka B.P.期间.
Abstract： The geochemical characteristics of major elements of Guixianhekou profile in the upper Hanjiang River valley are studied. Results show that： The major elements are SiO2, A12 03 and Fe203, Ca,Na,Mg,Si are leached out, while K,Fe,A1 relatively enriched in the paleosol So. The element mobility and migration ability of the major elements are ranked in the following order： Ca 〉Na 〉 Mg 〉 Si 〉 K 〉 Al 2〉 Fe. The migration of Ca, Na, K indicate that the profile had experienced a moderate degree of chemical weathering. The chemical index of alteration（CIA）,K20/ Na2 O, Si（）z/A12 03, （Ca（） q- K20 q- Na2 O）/A12 （）a and （ Alz 03 ＋ Fe2 03 ） / （ MgO ＋ CaO q- Na2 O） imply that chemical weathering was strong during the paleosol（S0） formation, while it was weak during the loess（L1, L,, L0） formation. The change of chemical weathering reveal that the first level terraces of upper Hanjiang River was formed in 18.0 ka B. P. and the climate was dry and cold. It turned to warm-humid from 11.5 ka B. P. , and the climate became the most warm and humid from 8. 5 ka B. P. , and reentered a period of relative drought since 3. 0 ka B. P.. The profile recorded four palaeoflood events,occurred during 12.5--12.4 ka B. P. ,7.5--7.0 ka B. P. ,3. 1--3.0 ka B.P. and 1.0--0.9 ka B. P. , respectively.
出处
《陕西师范大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第1期98-104,共7页
Journal of Shaanxi Normal University：Natural Science Edition
基金
国家自然科学基金资助项目(41271108
41030637)
中央高校基本科研业务费专项资金项目(GK201301003)
教育部博士点基金优先发展领域项目(20110202130002)
国家社会科学基金资助项目(11AZS009)
关键词
黄土
化学风化
元素迁移
归仙河口
汉江上游
loess
chemical weathering
element migration
Guixianhekou
the upper Hanjiang River
