Hydrothermal alteration of the surface volcanic rocks at the Acoculco geothermal field, Mexico: a multi-parametric approach
Por:
García-Soto, AY, Pandarinath, K, Santoyo, E, Gonzalez-Partida, E
Publicada:
1 dic 2024
Ahead of Print:
1 abr 2024
Categoría:
Geochemistry and petrology
Resumen:
The studies on hydrothermal alteration-induced effects in surface and subsurface rocks provide useful information in the characterization and exploitation of a geothermal reservoir. Generally, these studies are based on traditional, and reliable methods like petrography (primary and secondary minerals, and grade of alteration), and geochemistry (mobility of elements, changes in mass and concentration of elements, and fluid inclusions). Recently, apart from these established methods, some methods based on the geochemical (Chemical Index of Alteration, CIA; Weathering Index of Parkar, WIP; Loss on Ignition, LOI; and Sulfur, S) and rock magnetic properties (magnetic susceptibility, chi lf; and percentage frequency-dependent susceptibility, chi fd%) are also being applied in the identification of whether a rock is an altered or a fresh one. The Acoculco Geothermal Field (AGF), Mexico, is characterized by high temperature and very low permeability, and it is considered a promissory Enhanced Geothermal System. The following changes are observed in the rocks as a result of an increase in hydrothermal alteration: (1) an increase in CIA, LOI, and S values, and a decrease in WIP; (2) an increase in quartz and quartz polymorph minerals (silicification), and clay minerals (argillization); and (3) decrease in chi lf values. At AGF, the most altered surface acid rocks are characterized by entirely quartz and its polymorphs, and clay minerals. The present study also indicates the applicability of the binary plots of major elements (felsic vs mafic component) and rock magnetic parameters (chi lf vs. chi fd%). The rock with chi fd% value of 2-10 and chi lf value < 0.5 x 10(-6 )m(3) kg(-1) indicate the presence of single domain and stable single domain grains, which in turn suggests that it is an altered rock. These methods are simple to apply, rapid, reliable, and have the potential to become effective tools for the identification of hydrothermally altered rocks during the initial stage of geothermal exploration.
Filiaciones:
García-Soto, AY:
Univ Nacl Autonoma Mexico, Inst Energias Renovables, Apartado postal 34, Temixco 62580, Morelos, Mexico
Pandarinath, K:
Univ Nacl Autonoma Mexico, Inst Energias Renovables, Apartado postal 34, Temixco 62580, Morelos, Mexico
Santoyo, E:
Univ Nacl Autonoma Mexico, Inst Energias Renovables, Apartado postal 34, Temixco 62580, Morelos, Mexico
Gonzalez-Partida, E:
UNAM, Ctr Geociencias, Apartado Postal 1-742, Queretaro 76001, Queretaro, Mexico
hybrid, All Open Access
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