Vol. 58 No. 3 (2019)
Articles

Consideraciones sobre el sistema geotérmico de San Bartolomé de los Baños, Guanajuato (México), desde un análisis de la alteración hidrotermal y las inclusiones fluidas

Carles Canet
Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México
Augusto A. Rodríguez-Díaz
Instituto de Geofísica, Universidad Nacional Autónoma de México
Indra Daniela Bernal
Department of Geology Andean Geothermal Center of Excellence (CEGA) and Millennium Nucleus for Metal Tracing Along Subduction Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile
Teresa Pi
Instituto de Geología & LANGEM, Universidad Nacional Autónoma de México
María M. Sánchez-Córdova
Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México
Fernando Núñez-Useche
Instituto de Geología & LANGEM, Universidad Nacional Autónoma de México
Ruth Villanueva-Estrada
Instituto de Geofísica, Universidad Nacional Autónoma de México
Gabriel Molina
Facultad de Ingeniería, Universidad Nacional Autónoma de México
Martin Reich
Department of Geology Andean Geothermal Center of Excellence (CEGA) and Millennium Nucleus for Metal Tracing Along Subduction Facultad de Ciencias Físicas y Matemáticas Universidad de Chile
Berenice Peláez
Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México
Esteban Jiménez Salgado
Gerencia de Proyectos Geotermoeléctricos, Comisión Federal de Electricidad
Eduardo González-Partida
Centro de Geociencias, Universidad Nacional Autónoma de México
Fernando Sandoval Medina
Gerencia de Proyectos Geotermoeléctricos, Comisión Federal de Electricidad
Cinthya B. Carrillo-Sánchez
Facultad de Ingeniería, Universidad Nacional Autónoma de México

Published 2019-07-01

Keywords

  • Fault-controlled geothermal system,
  • steam-heated water,
  • silica sinter,
  • kaolinite,
  • fluid inclusion microthermometry
  • Sistemas geotérmicos controlados por fallas,
  • aguas calentadas por vapor,
  • sínter silícico,
  • caolinita,
  • microtermometría de inclusiones fluidas

How to Cite

Canet, C., Rodríguez-Díaz, A. A., Bernal, I. D., Pi, T., Sánchez-Córdova, M. M., Núñez-Useche, F., Villanueva-Estrada, R., Molina, G., Reich, M., Peláez, B., Jiménez Salgado, E., González-Partida, E., Sandoval Medina, F., & Carrillo-Sánchez, C. B. (2019). Consideraciones sobre el sistema geotérmico de San Bartolomé de los Baños, Guanajuato (México), desde un análisis de la alteración hidrotermal y las inclusiones fluidas. Geofísica Internacional, 58(3), 229-246. https://doi.org/10.22201/igeof.00167169p.2019.58.3.2063

Abstract

San Bartolomé de los Baños is a geothermal zone located in the southeast of the Guanajuato state in Mexico, and hosts near 150 thermal surface manifestations (hot springs), with discharge temperatures up to 92 °C and pH of 6.0?9.2. These manifestations, as well as surface hydrothermal alteration patches, are distributed along the N?S San Bartolomé fault, which in the study area has a displacement of ~100 m. This fault crosscuts a calc-alkaline volcanic sequence of Upper Miocene age that consists of a basal pyroclastic unit overlaid by basaltic lavas. Three suites of hydrothermal alteration occur at the surface: (a) silicification; (b) argillic; and (c) advanced argillic. Other hydrothermally-derived mineral assemblages are: (d) silica sinter; (e) silica- and sulfate-rich geyserite; and (f) quartz-calcite-fluorite-barite veinlets. Fluid inclusion microthermometry analysis of the veinlets show homogenization temperatures (Th) between 62 and 139 °C (with modal value at ~110 °C), and salinity between 2.4 and 10.4 % (weight NaCl equivalent). A rough correspondence between Th and salinity suggests that hydrothermal fluid mixed with meteoric surface water close to the discharge (at depths lesser than 50 m). Hydrothermal alteration assemblages indicate fluid temperature near the surface of ~100 °C and slightly alkaline pH, whereas silica sinter suggests a reservoir temperature >200 °C. Both hydrothermal alteration and hot springs are spatially restricted to the San Bartolome fault, which, along with the apparent absence of modern volcanic activity, indicates that the geothermal system is non-magmatic and fault controlled (extensional domain type).