| Title | The Tulancingo-Acoculco Caldera Complex, Puebla, Mexico: the Geology and Geophysics as Key Data for a Geothermal Energy Prospect |
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| Authors | AGUIRRE-DÃAZ, Gerardo J., LOPEZ-HERNANDEZ, Aida, PEREZ-FLORES, Marco, GONZALEZ-PARTIDA, Eduardo, DIAZ-CARREÑO, Erik H., COUTIÑO-TABOADA, Mariana E., JASSO-TORRES, Katia, RAMIREZ-MONTES, Miguel |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Volcano-tectonic caldera, geothermal energy, heat source, faults, Mexico, GEMex |
| Abstract | Acoculco (Puebla) is a potential site for geothermal energy and has been studied since the 1980s by Comisión Federal de Electricidad (CFE) Mexican agency. Previous studies indicate that Acoculco is an elliptical-shaped caldera, with 18 by 15 km in diameter, nested within the 32 km in diameter Tulancingo caldera (López-Hernández et al., 2009). Our stratigraphic and structural work suggests a new geological model for this complex; there is a Tulancingo caldera, but it is graben type, as defined in Aguirre-DÃaz (2008), linked to regional fault systems in the area. This interpretation agrees with geophysical studies and with the information from two deep wells (2000 m) in the central part of the complex. The Tulancingo-Acoculco caldera complex started activity at about 2.7 Ma and finished it at about 0.8 Ma, with four caldera collapses associated to pumice fallouts and ignimbrite-forming eruptions, with emplacement of lava domes in between and at the end. The youngest rocks are scoria cones and related mafic lavas as young as Pleistocene and probably Holocene, which are aligned to the fault trends. Geothermal heat in the zone is apparently related to this mafic volcanism controlled by the regional fault systems. Assuming the existence of a post-collapse remnant of the subcaldera silicic magma body, heat in this body may have been preserved by continuous inputs of mafic magma that fed the scoria cones. But it is more probable a direct link with the mafic Pleistocene volcanism for the heat source. This hypothesis would explain the heat anomaly just beneath the Acoculco dome complex, where there is magmatic cold gas emissions and temperatures greater than 250°C at 2000 m depth, and also would explain the aligned hot springs and hot water wells observed along the SE and NE borders of the Tulancingo graben caldera. Financed by GEMex grant 268074 SENER-CONACyT |