青藏高原东部长江河流溶质载荷主要离子地球化学研究

Major ion geochemistry of the dissolved loads from the Changjiang River on eastern Qinghai-Xizang Plateau

关键词:  青藏高原东部  长江  河流溶质载荷  主要离子  地球化学

Key words:  eastern Qinghai-Xizang Plateau  Changjiang River  dissolved load  major ion  geochemistry

摘要:

作者于2000年和2002年对青藏高原东部长江河流溶质载荷进行了较为系统的野外取样工作,并对主要离子地球化学特征进行了分析研究。数据分析表明,长江水系TZ⁺高于世界河流1250μ Eq的平均值,主要介于2000~3000μ Eq之间,其次为1000~2000μ Eq。总体上,高原东部长江水系TZ⁺可以与世界上其它造山带相比较。高原东部长江水系主要阴离子的相对丰度和分布表现出HCO₃^- > Si+Cl^-+SO₄^2-,河水富含HCO₃^-;阳离子主要表现为Ca²⁺ > Mg²⁺+Na⁺+K⁺,表明河水富含Ca离子特征。河水中富含HCO₃^-和Ca²⁺,说明高原东部长江水系流域盆地中碳酸盐岩(主要是灰岩)应是河流中主要离子的风化源岩。

Abstract:

The examination of major ion geochemistry is based on the field sampling of the dissolved loads from the Changjiang River on eastern Qinghai-Xizang Plateau in the years of 2000 and 2002. The analysis of the data has disclosed that the TZ⁺ values for the Changjiang River are higher than the mean values (1250 μ Eq)for all the rivers in the world, ranging mostly between 2000 and 3000 μ Eq and subordinately between 1000 and 2000 μ Eq. By and large, the abovementioned TZ⁺ values may be compared with those for other orogenic belts in the world. The river water is characterized by enriched HCO₃^-HCO₃^- > Si +Cl^-+SO₄^2-, Ca²⁺ > Mg²⁺ +Na⁺+ K⁺, implying that the river water is rich in Ca²⁺. The enrichment of HCO₃^- and Ca²⁺ in the river indicates that the carbonate rocks (especially limestone)should be interpreted as the weathered source rocks in the Changjiang drainage areas.