Shallow anatomy of hydrothermal systems controlled by the Liquiñe-Ofqui Fault System and the Andean Transverse Faults: Geophysical imaging of fluid pathways and practical implications for geothermal exploration

Pérez‐Estay, Nicolás; Molina, Eduardo; Roquer, Tomás; Aravena, Diego; Vargas, Jaime Araya; Morata, Diego; Arancibia, Gloria; Valdenegro, Pablo; García, Karin; Elizalde, Daniel

doi:10.1016/j.geothermics.2022.102435

Cited by 8 publications

(5 citation statements)

References 72 publications

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“…Thermal springs are clustered at the borders of tectonic blocks A and B (Liquiñe fault) and between blocks B and C (Río Lindo fault) (Figures 2 and 12a–12c). Geophysical imaging of geothermal resources across strands of the LOFS reveals N‐striking, steeply dipping conduits which likely represent fractured zones in the shallow crystalline bedrock (<30 m depth; Pérez‐Estay et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

Fault‐Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe‐Ofqui Fault System, Southern Andes (39°S)

et al. 2023

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Crustal deformation in transpressive tectonic settings is partitioned across fault‐bounded tectonic blocks whose borders may represent ideal loci for enhanced rock exhumation. Field and petrographic analysis, geothermobarometry, zircon U‐Pb geochronology, and zircon and apatite (U‐Th)/He thermochronology were applied to intrusive and metamorphic rocks to investigate exhumation patterns of fault blocks delimited by the Liquiñe‐Ofqui Fault System (LOFS), Southern Andes (39°S). Our integrated analyses document the relative influences of magmatism, fault‐driven differential exhumation, and fault‐controlled geothermal flow along the LOFS. Magmatism was concentrated in the Early to Late Jurassic (∼182–151 Ma), Early Cretaceous (∼116–104 Ma), and Miocene (∼17–6 Ma). Dextral mylonitic deformation was most likely coeval with the Miocene pulse of magmatism. Tectonic exhumation occurred across a positive flower structure during the Late Miocene to Early Pleistocene (∼6–2 Ma), and affected kilometric‐scale tectonic blocks bound by N‐striking, steeply dipping faults of the LOFS. Fault‐controlled geothermal flow occurred from the Early Pleistocene to the present‐day (∼1.5 Ma‐present). Our results suggest that individual faults not only facilitate exhumation of tectonic blocks but also act as pathways for long‐term hydrothermal fluid flow.

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Section: Discussionmentioning

confidence: 99%

Fault‐Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe‐Ofqui Fault System, Southern Andes (39°S)

et al. 2023

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“…Reconstruction of the geological setting of a thermal system is one of the steps necessary for assessing the potential of a geothermal resource. Geophysical investigations have been profitably used to address this topic since their results can be used to indirectly reconstruct the geometry of the reservoir and of the fault systems driving the fluid circulation [19,[22][23][24]39,[61][62][63]71,72]. These methods are particularly applicable in areas where the geological data are limited to a few stratigraphic logs or where the alluvial cover conceals the subsurface structure.…”

Section: Discussionmentioning

confidence: 99%

“…The resistivity generally depends on the mineralogical composition of the subsurface, its porosity, the water content, and the physical and chemical properties of the water [60]. ERT has been profitably applied in hydrogeological and structural investigations in many geothermal systems [22][23][24][61][62][63].…”

Section: Electrical Resistivity Tomographymentioning

confidence: 99%

“…Based on the research objectives and the geological and hydrogeological settings of the study area, different geophysical approaches can be applied. For the exploration of geothermal resources [21][22][23][24][25][26], they can be used to: (i) assess the distribution of lithologies, (ii) reconstruct the geometry of the aquifer, and (iii) reconstruct the geometry of faults and their damage zones. Among them, electrical resistivity tomography (ERT) and seismic methods can provide a detailed 3D local scale reconstruction of the subsurface.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of Fault Architecture in the Natural Thermal Spring Area of Daruvar Hydrothermal System Using Surface Geophysical Investigations (Croatia)

et al. 2023

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The sustainable utilization of geothermal energy mostly depends on the characteristics of the geothermal resource from which it is extracted. Among others, detailed geological modeling is a key factor for estimating the potential of a geothermal resource. This research focuses on the modeling and reconstruction of the geological setting of the Daruvar thermal spring area using geophysical techniques. An integrated geophysical approach based on electrical resistivity tomography (ERT) and both active and passive seismic (MASW and HVSR) methods was used. Based on ERT results and the stratigraphic logs of the wells in Daruvar, three resistivity layers/geological units were identified. The deepest layer with resistivity < 150 Ωm is the Triassic carbonate that constitutes the thermal aquifer. Sharp lateral variations in the resistivity distributions within the bedrock were interpreted as fault damage zones saturated with thermal waters. Integrating the results of the seismic methods, the thickness of the first seismic layer that corresponds to the Quaternary cover was estimated from 5 to 20 m. Here, results of the geophysical investigations were combined into a 3D geological model highlighting the occurrence of subvertical N-S and E-W trending faults in the Daruvar spring area. The N-S-trending fault was interpreted as a fault plane parallel to the regionally mapped Daruvar fault. This fault juxtaposes the Triassic carbonate complex of the thermal aquifer with a Neogene sedimentary sequence of significantly lower permeability. Neogene–Quaternary tectonic activity further increased the fracturing and the permeability field in the Daruvar spring area, as proven by the smaller scale E-W faults and the well logs. This fracture network permits a quick upwelling of thermal fluids resulting in thermal springs with temperatures up to 50 °C. This work proves that the construction of a detailed geological model is crucial for assessing the reservoir and fault geometries in thermal systems hosted in fractured carbonate rocks.

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“…Electrical resistivity tomography (ERT) is a non-invasive and fast geophysical method, usually applied to obtain high-resolution 2D images of the subsurface resistivity. This method can be used to define the geometry of an aquifer, delineate the structural and lithological setting of the subsurface, and determine the geometry of faults and the width of the connected, water-saturated fault zones [64][65][66].…”

Section: Geophysical Investigationsmentioning

confidence: 99%

Multidisciplinary Research of Thermal Springs Area in Topusko (Croatia)

et al. 2023

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Topusko is the second warmest natural thermal water spring area in Croatia, located at the southwest edge of the Pannonian Basin System. Due to favourable geothermal properties, these waters have been used for heating and health and recreational tourism since the 1980s. Thermal springs with temperatures up to 50 °C are the final part of an intermediate-scale hydrothermal system. However, systematic research on the Topusko spring area has not been conducted to lay the foundation for sustainable resource utilisation. Multidisciplinary research including the hydrogeochemical characterisation of naturally emerging thermal water, an electrical resistivity tomography (ERT) investigation conducted to reconstruct the subsurface geology, and hydrogeological parametrisation of the geothermal aquifer was carried out to refine the existing local conceptual model. The results show Ca-HCO3 facies of Topusko thermal waters, which get heated in a Mesozoic carbonate aquifer. The water equilibrium temperature in the geothermal aquifer is estimated to be 78 °C based on the SiO2-quartz geothermometer. The fault damage zone, which enables the upwelling of thermal water, was identified by ERT investigations. The transmissivity values of the aquifer derived from the results of step-drawdown tests range from 1.8 × 10−2 to 2.3 × 10−2 m2/s. Further multidisciplinary research is necessary to improve the existing conceptual model of the Topusko hydrothermal system.

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Shallow anatomy of hydrothermal systems controlled by the Liquiñe-Ofqui Fault System and the Andean Transverse Faults: Geophysical imaging of fluid pathways and practical implications for geothermal exploration

Cited by 8 publications

References 72 publications

Fault‐Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe‐Ofqui Fault System, Southern Andes (39°S)

Fault‐Driven Differential Exhumation in a Transpressional Tectonic Setting: A Combined Microstructural and Thermochronologic Approach From the Liquiñe‐Ofqui Fault System, Southern Andes (39°S)

Reconstruction of Fault Architecture in the Natural Thermal Spring Area of Daruvar Hydrothermal System Using Surface Geophysical Investigations (Croatia)

Multidisciplinary Research of Thermal Springs Area in Topusko (Croatia)

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