干旱区生态环境知识资源中心(Arid): Chemical and isotopic evolution of groundwater through the active Andean arc of Northern Chile

Arid

DOI	10.1016/j.chemgeo.2019.04.011
	Chemical and isotopic evolution of groundwater through the active Andean arc of Northern Chile
	Godfrey, L., V 1; Herrera, C.2; Gamboa, C.2; Mathur, R.3
通讯作者	Godfrey, L., V
来源期刊	CHEMICAL GEOLOGY
ISSN	0009-2541
EISSN	1872-6836
出版年	2019
卷号	518 页码:32-44
英文摘要	The role of rock-water reactions, leakage of sedimentary brine, evaporite dissolution and variations in lithology on the chemical and isotopic evolution of groundwater draining the active arc and Preandean basins in the Antofagasta Region of northern Chile has been investigated using Li, B and Sr isotopes. The studied basin is that of the upper Loa river and its sub-basins, which is adjacent to the basin occupied by the Salar de Atacama where Li-rich brines are commercially exploited. Due to the arid climate, water draining this part of the Andes does so primarily through the subsurface. Water from a thermal source is a common component of water sampled, but its geochemical signature evolves through multiple processes including dilution, cold rock-water reactions, influxes of sedimentary brine and evaporite mineral dissolution. These processes lead to a range of Li and B concentrations in groundwater (0.01-14 mg/L and 0.18-20 mg/L) and isotope compositions (-1 to +12 parts per thousand and -6 to +14 parts per thousand). The effect of rock dissolution on delta Li-7 and delta B-11 within aquifers is apparent from their low values, but even in streams these values only undergo small increases relative to other rivers worldwide. This may be due to the weathering of ignimbrites producing water with less Al and limited clay formation, the large reservoir of thermally-sourced Li and B of which only a small component is removed, and because the streams acquire groundwater through their beds. The wider range in delta B-11 is a result of variable lithology and dissolution of evaporite minerals, which have lesser effects on delta Li-7. Our multi-isotope approach highlights the role of lithology and different processes in defining groundwater chemistry. Isotopic signatures derived from marine sediments are recognizable in some springs even though this type of rock has nearly no surface exposure due to extensive volcanic rock cover, and are acquired directly or via incorporation of these sediments into volcanic systems. These high-Cl rocks can weather to produce water with a chemical composition like that of sedimentary brine but is distinguishable through delta B-11 composition. Combination of Sr-87/Sr-86, delta Li-7 and delta B-11 also indicate that mixed salts which contribute to groundwater draining the ignimbrite covered areas of the basin did not form following cold temperature weathering, but from water where thermal contributions dominated solute budgets keeping delta Li-7 low, and Li/Cl and B/Cl high compared to other fluid reservoirs such as seawater. We propose that these saline systems lay within the confines of one of the multiple late-Miocene-Pliocene calderas following the active stage of volcanism and while heat gradients remained high.
英文关键词	Lithium isotopes Boron isotopes Strontium isotopes Water-rock interactions Northern Chile Volcanic arc
类型	Article
语种	英语
国家	USA ; Chile
收录类别	SCI-E
WOS记录号	WOS:000468423200004
WOS关键词	TATIO GEOTHERMAL-FIELD ; PUNA VOLCANIC COMPLEX ; DE-ATACAMA BASIN ; DISSOLUTION RATES ; HYDROTHERMAL SYSTEMS ; BORATE DEPOSITS ; CALAMA BASIN ; BORON ; LITHIUM ; SALAR
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/214869
作者单位	1.Rutgers State Univ, Dept Earth & Planetary Sci, Piscataway, NJ 08854 USA; 2.Univ Catolica Norte, Dept Ciencias Geol, Antofagasta, Chile; 3.Juniata Coll, Dept Geol, Huntingdon, PA 16652 USA
推荐引用方式 GB/T 7714	Godfrey, L., V,Herrera, C.,Gamboa, C.,et al. Chemical and isotopic evolution of groundwater through the active Andean arc of Northern Chile[J],2019,518:32-44.
APA	Godfrey, L., V,Herrera, C.,Gamboa, C.,&Mathur, R..(2019).Chemical and isotopic evolution of groundwater through the active Andean arc of Northern Chile.CHEMICAL GEOLOGY,518,32-44.
MLA	Godfrey, L., V,et al."Chemical and isotopic evolution of groundwater through the active Andean arc of Northern Chile".CHEMICAL GEOLOGY 518(2019):32-44.