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The use of newly formed minerals to characterize geothermal reservoirs and their cap rock: examples from intracontinental extensional basins and volcanic islands in subduction context
Ledésert, B.A. Application of Minerals for the Characterization of Geothermal Reservoirs and Cap Rock in Intracontinental Extensional Basins and Volcanic Islands in the Context of Subduction. Minerals2024, 14, 263.
Ledésert, B.A. Application of Minerals for the Characterization of Geothermal Reservoirs and Cap Rock in Intracontinental Extensional Basins and Volcanic Islands in the Context of Subduction. Minerals 2024, 14, 263.
Ledésert, B.A. Application of Minerals for the Characterization of Geothermal Reservoirs and Cap Rock in Intracontinental Extensional Basins and Volcanic Islands in the Context of Subduction. Minerals2024, 14, 263.
Ledésert, B.A. Application of Minerals for the Characterization of Geothermal Reservoirs and Cap Rock in Intracontinental Extensional Basins and Volcanic Islands in the Context of Subduction. Minerals 2024, 14, 263.
Abstract
Geothermal energy aims at harnessing the heat of the Earth to produce energy, from the near-surface to great depths. Emphasis is put on geothermal reservoirs in crystalline rocks, hence vol-canic islands and crystalline basements of sedimentary basins based on three examples world-wide. Hot brines circulate in those rocks and are responsible for their hydrothermal alteration because of fluid-rock interactions. This includes dissolution of preexisting minerals and crystal-lization of newly formed ones which provide many information of crucial importance for a better exploration of those reservoirs. For example, the crystallization of clay minerals results from the dissolution of preexisting minerals (feldspar and ferro-magnesian minerals in plutonic, volcanic or metamorphic rocks) or from the direct precipitation from geothermal brines, in specific condi-tions. Clay minerals are found in both the geothermal reservoirs and in the clay-cap found above them. Other newly formed minerals such as quartz, carbonates or sulfates have also recorded the conditions of temperature and salinity encountered by fossil reservoirs which can be evaluated thanks to the study of fluid inclusions trapped during their crystallization. This paper presents results from several geothermal deep sites and surface analogues to pinpoint the role played by newly-formed minerals in the characterization of geothermal reservoirs and their cap-rock.
Environmental and Earth Sciences, Geochemistry and Petrology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
