Fault-controlled geothermal fluids of the northern Trans-Mexican Volcanic Belt: A geochemical and isotopic study of the Los Geysers field (Valley of Queretaro, Mexico)
Por:
González-Guzmán R., Inguaggiato C., Peiffer L., Weber B., Kretzschmar T.
Publicada:
1 ene 2019
Resumen:
This study focuses on the geochemical and isotopic composition of natural spring waters and gases discharging at Los Geysers thermal area (northern Trans-Mexican Volcanic Belt, TMVB) and its relations to the regional tectonic framework. Water is of Na-HCO3 type and samples were collected at temperatures ranging from 48 °C to 98 °C and pH from 6.8 to 9.3. Stable isotope compositions (-10.0 to -8.0‰ for d18O and -75.6 to -69.7‰ for dD) deviate from the global and local meteoric lines suggesting fractionation by steam loss The 87Sr/86Sr values of the thermal waters range from 0.70664 to 0.70698 indicating that most of the strontium comes from the dissolution of carbonate belonging to the late Berriasian to early Valanginian in the Guanajuato conglomerate group and a minor component of less radiogenic Sr from Paleogene–Neogene volcano-sedimentary and volcanic rocks. Solute geothermometers reveal a reservoir temperature around 164 °C. A mixture between air and hydrothermal CO2 composes the bubbling gases. Helium isotopes data (R/Ra = 0.96–1.71) and 4He/20Ne ratios (0.53–9.41) reveal that helium is dominated by a radiogenic component with a considerable mantle-He contribution (up to 20.8%). Since there is no active volcanism at the northern TMVB, mantle-He is best explained by transport of volatiles along active faults reaching the crust-mantle boundary. The conceptual hydrogeochemical model involves a thermal aquifer at ~1000 m depth which is recharged by regional meteoric water flow, a high thermal gradient (~153 °C/km) and fast fluid upflow to the surface along discontinuities related to regional horst and graben tectonics. © 2019 Elsevier B.V.
Filiaciones:
González-Guzmán R.:
Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carretera Ensenada-Tijuana 3918, Zona Playitas, Ensenada, Baja California 22860, Mexico
Inguaggiato C.:
Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carretera Ensenada-Tijuana 3918, Zona Playitas, Ensenada, Baja California 22860, Mexico
Peiffer L.:
Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carretera Ensenada-Tijuana 3918, Zona Playitas, Ensenada, Baja California 22860, Mexico
Weber B.:
Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carretera Ensenada-Tijuana 3918, Zona Playitas, Ensenada, Baja California 22860, Mexico
Kretzschmar T.:
Departamento de Geología, División de Ciencias de la Tierra, CICESE, Carretera Ensenada-Tijuana 3918, Zona Playitas, Ensenada, Baja California 22860, Mexico
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