10-4 Geochemical and Geophysical Characterization of a Coastal Geothermal System: Buena Vista, Baja California Sur, Mexico

Session: Geomorphological, Hydrologic, and Geothermal investigations of basin aquifers in Baja California Sur (BCS), Mexico (Posters)

Poster Booth No.: 41

Presenting Author:

Ashley Vega Donato

Authors:

Vega Donato, Ashley Natalie¹, Peiffer, Loic², Carrillo López, Jonathan ³, Inguaggiato, Claudio⁴, Gómez Treviño, Enrique⁵, Trasviña Castro, Armando⁶

(1) Departamento de Geofísica, CICESE, Ensenada, Baja California, Mexico, (2) Departamento de Geología, Unidad La Paz, CICESE, La Paz, Baja California Sur, , (3) Departamento de Geofísica Aplicada, CICESE, Ensenada, Baja California, Mexico, (4) Departamento de Geología, CICESE, Ensenada, Baja California, Mexico, (5) Departamento Geofísica Aplicada, CICESE, Ensenada, Baja California, Mexico, (6) Departamento de Oceanología, CICESE, La Paz, Baja California Sur, Mexico,

Abstract:

Geothermal systems in the Baja California Peninsula are strongly controlled by regional tectonics. Thermal manifestations commonly occur along fault-controlled pathways between highland areas and the coast, expressed as hot springs, anomalously warm shallow wells, and diffuse coastal discharge zones.

This study investigates the coastal geothermal system of Buena Vista, in southeastern Baja California Sur, using an integrated geochemical and geophysical approach. Groundwater from shallow wells was sampled in November 2025 and is currently being analyzed for major and trace elements as well as O–H isotopes to determine the origin of the thermalism, characterize water–rock interaction processes, and infer deep reservoir equilibrium temperatures. In parallel, two-dimensional electrical resistivity tomography (ERT) and magnetometric surveys were conducted during the same field campaign to identify resistivity and magnetization contrasts associated with geological structures such as faults and lithological contacts, as well as anomalies related to hydrothermal circulation and mineral alteration.

Shallow well waters exhibit predominantly alkaline pH values (up to 9.02) and temperatures ranging from 30 to 62 °C. Their spatial distribution reveals a decrease toward the southwest, suggesting strong structural and/or hydrodynamic control on geothermal fluid circulation. Geochemical and geophysical data are currently being processed and will be presented at the conference. Their integration will allow the development of a conceptual model of the Buena Vista coastal geothermal system, delineating zones of geothermal potential, their spatial extent, and the flow pathways.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

doi: 10.1130/abs/2026CD-13388

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