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Lithium, uranium, and noble gas Salar de Atacama


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Created: Mar 07, 2026 at 5:30 a.m. (UTC)
Last updated: May 13, 2026 at 2:14 p.m. (UTC) (Metadata update)
Published date: May 13, 2026 at 2:14 p.m. (UTC)
DOI: 10.4211/hs.b0b884a33f9b40c685c424cca5f6c36e
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Sharing Status: Published
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Abstract

Lithium (Li) rich brines in arid continental basins are critical resources for the global energy transition, yet the processes governing extreme Li enrichment remain debated. Evaporative concentration is widely invoked as the dominant mechanism, but the role of long-term crustal residence has not been quantitatively constrained. Here, we integrate Li concentrations and isotopes (δ⁷Li), uranium activity ratios (²³⁴U/²³⁸U), noble gas systematics (³He/⁴He, ⁴He, ²⁰Ne, ⁴⁰Ar), and chlorofluorocarbon tracers from recharge waters, transitional aquifers, and central brines of the Salar de Atacama, Chile. Radiogenic ⁴He concentrations exceed 2 × 10⁻⁶ ccSTP g⁻¹ in evolved brines, while R/Ra values decrease to <0.03, indicating dominant crustal helium accumulation and negligible mantle input. Assuming upper crust production rates of 1–3 × 10⁻¹² ccSTP g⁻¹ yr⁻¹, these concentrations imply apparent residence times of ~0.5–2 Myr. Uranium activity ratios progressively approach secular equilibrium along basin flow paths, recording sustained water–rock interaction. Li concentrations increase by more than two orders of magnitude toward hydrologically isolated brine domains, yet δ⁷Li remains comparatively restricted, indicating early-stage fractionation followed by conservative concentration. The decoupling of Li enrichment from mantle helium signatures and the conservative behavior of ²⁰Ne demonstrate that Li rich brines form through multimillion-year crustal storage within a structurally open but hydrologically closed basin. Evaporation concentrates solutes, but time integrated crustal interaction governs the magnitude of enrichment. These results provide quantitative temporal constraints on mineral resource formation in continental salars.

Subject Keywords

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
North Latitude
-22.5000°
East Longitude
-67.5000°
South Latitude
-24.3000°
West Longitude
-69.0000°

Temporal

Start Date:
End Date:

Content

How to Cite

Dar, T. (2026). Lithium, uranium, and noble gas Salar de Atacama, HydroShare, https://doi.org/10.4211/hs.b0b884a33f9b40c685c424cca5f6c36e

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

Comments

Tanveer Dar 2 months, 3 weeks ago

Lithium, Uranium, and Noble Gas Dataset – Salar de Atacama
Description

This dataset contains dissolved lithium concentrations and isotopes (δ⁷Li), uranium concentrations and activity ratios (²³⁴U/²³⁸U), noble gas concentrations (He, Ne, Ar, Kr, Xe), and chlorofluorocarbon (CFC) measurements from groundwater, surface water, transitional aquifers, and brine samples collected in the Salar de Atacama basin, Chile.

Variables and Units

Li (mg/L) – Dissolved lithium concentration

δ⁷Li (‰, relative to L-SVEC) – Lithium isotope composition

²³⁸U (ng/g) – Uranium concentration

²³⁴U/²³⁸U – Uranium activity ratio (dimensionless)

³He, ⁴He, ²⁰Ne, ²²Ne, ³⁶Ar, ⁴⁰Ar, ⁸⁴Kr, ¹³⁰Xe (ccSTP g⁻¹) – Dissolved noble gas concentrations

R/Rₐ – Helium isotope ratio relative to air (Rₐ = 1.39 × 10⁻⁶)

Specific Conductivity (mS/cm)

Temperature (°C)

DO (%) – Dissolved oxygen

CH₄, CO₂ (ccSTP/g)
bbreviations

GW – Groundwater

SW – Surface water

TPB – Transition zone brine

ASW – Air-saturated water

⁴He* – Radiogenic helium (atmospheric component removed using ²⁰Ne correction)

Analytical Notes

Radiogenic helium (⁴He*) was calculated by subtracting atmospheric contributions using measured ²⁰Ne concentrations. Residence times were estimated assuming upper continental crust production rates of (1–3) × 10⁻¹² ccSTP g⁻¹ yr⁻¹.

Contact

Tanveer Dar
Department of Earth, Geographic and Climatic Sciences
University of Massachusetts Amherst

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