Weathering processes in the Indus River Basin: implications from riverine carbon, sulfur, oxygen, and strontium isotopes
Weathering processes in the Indus River Basin: implications from riverine carbon, sulfur, oxygen, and strontium isotopes
复制标题
DOI：
10.1016/s0009-2541(99)00246-6
复制
发表时间：
2000-10-01
期刊：
影响因子：
3.9
通讯作者：
Veizer, J
中科院分区：
文献类型：
--
作者：
Karim, A;Veizer, J
本研究涉及印度河流域（IRB）C、O、S和Sr的主要离子和同位素系统学。印度河及其大部分源头支流的主要离子化学为Ca 2 +> Mg 2 +>（Na+ + K+）和HCO 3->（SO 42- + Cl-）> Si。然而，在低地支流和旁遮普的一些河流中，（Na+ + K+）和（SO 42- + Cl-）占主导地位。循环盐，重要的本地Na+在稀释的源头支流，构成约5%的年度溶质输送的印度河。风化的两个岩性，沉积碳酸盐岩和结晶岩，控制溶解无机碳（DIC）的浓度和碳同位素系统学在整个印度河，但湍流和较低的温度在源头，并存储在水库中，印度河中下游促进一些平衡与大气中的二氧化碳。硫酸盐的硫和氧同位素组成的综合证据驳斥了这些矿物的溶解在IRE水化学中起重要作用的主张，并表明任何溶解的硫酸盐都是由硫化物矿物的氧化产生的。（或甚至更高的一些支流）的总Na+和K+，下降到低于40%的印度河退出造山带。相反，约三分之二的Ca ~（2+）和Mg ~（2+）在上印度河（在某些支流中为70%）和四分之三的下印度河（在下印度河）中来自沉积碳酸盐。的Sr-87/Sr-86的比例往往上升，增加比例的硅酸盐衍生的阳离子在源头支流和印度河的上部和中部，但在印度河下游的相位或逆转。在河口附近，Ca 2 + + Mg 2+和Na+ + K+的排放加权平均贡献分别约占总浓度的1/4和2/3。(C)2000 Elsevier Science B. V.保留所有权利。
This study deals with the major ions and isotope systematics for C, O, S, and Sr in the Indus River Basin (IRB). Major ion chemistry of the Indus, and most of its headwater tributaries, follow the order Ca2+> Mg2+> (Na+ + K+) and HCO3-> (SO42- + Cl-) > Si. In the lowland tributaries and in some of the Punjab rivers, however, (Na+ + K+) and (SO42- + Cl-) predominate. Cyclic salts, important locally for Na+ in dilute headwater tributaries, constitute about 5% of the annual solutes transported by the Indus. Weathering of two lithologies, sedimentary carbonates and crystalline rocks, controls the dissolved inorganic carbon (DIC) concentrations and its carbon isotope systematics throughout the Indus, but turbulent flow and lower temperatures in the headwaters, and storage in reservoirs in the middle and lower Indus promote some equlibration with atmospheric carbon dioxide. Combined evidence from sulfur and oxygen isotopic composition of sulfates refutes the proposition that dissolution of these minerals plays a significant role in the IRE hydrochemistry and suggests that any dissolved sulfates were derived by oxidation of sulfide minerals.In the upper Indus, silicate weathering contributes as much as 75% (or even higher in some tributaries) of the total Na+ and K+, declining to less than 40% as the Indus exits the orogen. In contrast, about two-thirds of Ca2+ and Mg2+ in the upper Indus lover 70% in some tributaries) and three-fourth in the lower Indus, are derived from sedimentary carbonates. The Sr-87/Sr-86 ratios tend to rise with increasing proportions of silicate derived cations in the headwater tributaries and in the upper and middle Indus, but are out of phase or reversed in the lower Indus. Finally, close to the river mouth, the discharge weighted average contribution of silicate derived Ca2+ + Mg2+ and silicate derived Na+ + K+ are, respectively, about one-fourth and two-thirds of their total concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.