BAEZ Walter Ariel
Structural control on geothermal circulation in the Cerro Tuzgle Tocomar geothermal volcanic area (Puna plateau, Argentina).
GUIDO GIORDANO; ANNAMARIA PINTON; PAOLA CIANFARRA; WALTER BAEZ; AGOSTINA CHIODI; JOSÉ VIRAMONTE; GIANLUCA NORINI; GIANLUCA GROPPELLI
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
ELSEVIER SCIENCE BV
Lugar: Amsterdam; Año: 2013 vol. 249 p. 77 - 94
The reconstruction of the stratigraphical?structural framework and the hydrogeology of geothermal areas is fundamental for understanding the relationships between cap rocks, reservoir and circulation of geothermal ﬂuids and for planning the exploitation of the ﬁeld. The Cerro Tuzgle?Tocomar geothermal volcanic area (Puna plateau, Central Andes, NW Argentina) has a high geothermal potential. It is crossed by the active NW?SE trans-Andean tectonic lineament known as the Calama?Olacapato?Toro (COT) fault system, which favours a high secondary permeability testiﬁed by the presence of numerous springs.This study presents new stratigraphic and hydrogeological data on the geothermal ﬁeld, together with the analysis from remote sensed image analysis of morphostructural evidences associated with the structural framework and active tectonics. Our data suggest that the main geothermal reservoir is located within or below the Pre-Palaeozoic?Ordovicianbasement units, characterised by unevenly distributed secondary permeability. The reservoir is recharged by inﬁltration in the ridges above 4500 m a.s.l., where basement rocks are in outcrop. Below 4500 m a.s.l., the reservoir is covered by the low permeable Miocene?Quaternary units that allow a poor circulation of shallow groundwater. Geothermal ﬂuids upwell in areas with more intense fracturing, especially where main regional structures, particularly NW?SE COT-parallel lineaments, intersect with secondary structures, such as at the Tocomar ﬁeld. Away from the main tectonic features, such as at the Cerro Tuzgle ﬁeld, the less developed network of faults and fractures allows only a moderate upwelling of geothermal ﬂuids and a mixing between hot and shallow cold waters. The integration of ﬁeld-based and remote-sensing analyses at the Cerro Tuzgle?Tocomar area proved to be effective in approaching the prospection of remote geothermal ﬁelds, and in deﬁning the conceptual model for geothermal circulation.