Arid
DOI10.1016/S0012-8252(03)00037-0
The origin of brines and salts in Chilean salars: a hydrochemical review
Risacher, F; Alonso, H; Salazar, C
通讯作者Risacher, F
来源期刊EARTH-SCIENCE REVIEWS
ISSN0012-8252
出版年2003
卷号63期号:3-4页码:249-293
英文摘要

Northern Chile is characterized by a succession of north-south-trending ranges and basins occupied by numerous saline lakes and salt crusts, collectively called salars. Fossil salt crusts are found to the west in the extremely arid Central Valley, while active salars receiving permanent inflows fill many intravolcanic basins to the east in the semiarid Cordillera. Sea salts and desert dust are blown eastward over the Cordillera, where they constitute an appreciable fraction of the solute load of very dilute waters (salt content < 0.1 g/l). The weathering of volcanic rocks contributes most components to inflow waters with salt content ranging from 0.1 to 0.6 g/l. However, the average salt content of all inflows is much higher: about 3.2 g/l. Chemical composition, Cl/Br ratio, and O-18-H-2 isotope contents point to the mixing of very dilute meteoric waters with present lake brines for the origin of saline inflows. Ancient gypsum in deep sedimentary formations seems to be the only evaporitic mineral recycled in present salars. Saline lakes and subsurface brines are under steady-state regime. The average residence time of conservative components ranges from a few years to some thousands years, which indicates a permanent leakage of the brines through bottom sediments. The infiltrating brines are recycled in the hydrologic system where they mix with dilute meteoric waters. High heat flow is the likely driving force that moves the deep waters in this magmatic arc region. Active Chilean salars cannot be considered as terminal lakes nor, strictly speaking, as closed basin lakes. Almost all incoming salts leave the basin and are transported elsewhere. Moreover, the dissolution of fossil salt crusts in some active salars also carries away important fluxes of components in percolating brines.


Evaporative concentration of inflow waters leads to sulfate-rich or calcium-rich, near-neutral brines. Alkaline brines are almost completely lacking. The alkalinity/calcium ratio of inflow waters is lowered by the oxidation of native sulfur (reducing alkalinity) and the deposition of eolian gypsum (increasing Ca concentration). Theoretically, SO4-rich inflow waters and their derived SO4-rich brines should be found in the intravolcanic basins of the Cordillera because of the ubiquity of native sulfur, while Ca-rich brines should prevail in sedimentary basins where Ca-rich minerals are abundant. This relation is perfectly observed in the salar de Atacama, the largest in Chile. However, several salars located within the volcanic Cordillera belong to the Ca-rich group. Inflows and brines may have acquired their Ca-rich composition in Pleistocene time when their drainage basins were mainly sedimentary. Later on, recent lava flows and ignimbrites covered the sedimentary formations. Underground waters may have kept their early sedimentary signature by continuous recycling. However, the weathering of volcanic rocks tend to slowly shift the water compositions from the Ca-rich to the SO4-rich type. (C) 2003 Elsevier Science B.V All rights reserved.


英文关键词northern Chile hydrochemistry closed basin salar salt recycling brine evolution
类型Article
语种英语
国家France ; Chile
收录类别SCI-E
WOS记录号WOS:000187032700002
WOS关键词AMORPHOUS SILICA SOLUBILITIES ; ANDEAN FORE-ARC ; NORTHERN CHILE ; NATURAL-WATERS ; ATACAMA-ALTIPLANO ; SALINE LAKES ; DE-ATACAMA ; GEOCHEMICAL EVOLUTION ; BOLIVIAN ALTIPLANO ; STABLE-ISOTOPES
WOS类目Geosciences, Multidisciplinary
WOS研究方向Geology
来源机构French National Research Institute for Sustainable Development
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/144440
作者单位(1)CNRS, IRD, Ctr Geochim Surface, F-67000 Strasbourg, France;(2)Univ Catolica Norte, Dept Quim, Angamos 0610, Antofagasta, Chile;(3)Minist Obras Publ, Direcc Gen Aguas, Santiago 248, Chile
推荐引用方式
GB/T 7714
Risacher, F,Alonso, H,Salazar, C. The origin of brines and salts in Chilean salars: a hydrochemical review[J]. French National Research Institute for Sustainable Development,2003,63(3-4):249-293.
APA Risacher, F,Alonso, H,&Salazar, C.(2003).The origin of brines and salts in Chilean salars: a hydrochemical review.EARTH-SCIENCE REVIEWS,63(3-4),249-293.
MLA Risacher, F,et al."The origin of brines and salts in Chilean salars: a hydrochemical review".EARTH-SCIENCE REVIEWS 63.3-4(2003):249-293.
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