Publication Date:
2022-02-21
Description:
This work presents hydrochemical results for groundwater and dissolved gas samples collected from a thermal
and cold aquifer in the Juchipila Basin, in southern Sierra Madre Occidental, central Mexico. Thermal springs in
the Juchipila Basin reach temperatures of 60 ◦C, these manifestations are not related to recent or active volcanism
as are all the known geothermal fields in Mexico. The thermal waters (〉32 ◦C) are Na-HCO3 and Na-SO4
type, with an anomalous concentration of F, B, Li, and As. Their chemistry likely results from water-rock
interaction processes. The cold waters (〈32 ◦C) have a Ca-HCO3 composition typical of recent infiltration and
shallow flow, but they have an anomalous concentration of NO3. The δ2H and δ18O indicate a common meteoric
source for the warm and cold water plotting along an evaporation line. The waters have higher CO2 and He
concentrations than the air-saturated water. The helium composition is mainly atmospheric and terrigenous with
a mantle helium contribution of up to 14%. This suggests that faults affecting the region are deeply rooted,
permitting mantle helium uprise. Geothermometry gives mean reservoir temperatures of 58–102 ◦C. Based on
these results, we propose a model of hydrothermal circulation in the Juchipila Basin, in which rainwater infiltrates
deeply through the graben edges fault system, dissolves ions and crustal helium, incorporates mantle
helium, while heated by the geothermal gradient, and eventually surges and mixes with the cold, shallow aquifer
along faults cutting the whole succession within the graben.
Description:
Published
Description:
102076
Description:
1TR. Georisorse
Description:
JCR Journal
Keywords:
Hydrogeochemical processes
;
Helium isotopes
;
Water stable isotopes
;
Unconventional geothermal system
;
Mexico
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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