Multidisciplinary approach for the exploration of remote geothermal fields: The Tocomar Geothermal System case study (Puna plateau, Argentina).

GIORDANO, GUIDO; AHUMADA, MARIA FLORENCIA; ALDEGA, LUCA; BÁEZ, WALTER; BECCHIO, RAUL; BIGI, SABINA; CARICCHI, CHIARA; CHIODI, AGOSTINA; CORRADO, SVEVA; DE BENEDETTI, ARNALDO; FAVETTO, ALICIA; FILIPOVICH, RUBEN; FUSARI, ALESSANDRO; GROPELLI, GIANLUCA; INVERNIZZI, CHIARA; MAFFUCCI, ROBERTA; NORINI, GIANLUCA; PINTON, ANNAMARIA; POMPOSIELLO, CRISTINA; TASSI, FRANCO; TAVIANI, SARA; VIRAMONTE, JOSE GERMAN

Strasbourg

Congreso; European Geothermal Congress 2016; 2016

European Geothermal Energy Council

The reconstruction of the stratigraphical?structuralframework and the hydrogeology andhydrogeochemistry of geothermal areas isfundamental for understanding the relationshipsbetween cap rocks, reservoir and circulation ofgeothermal fluids and for planning the exploitation ofgeothermal fields. The Tocomar geothermal volcanicarea (Puna plateau, Central Andes, NW Argentina) hasa high geothermal potential. It is crossed by the activeNW?SE trans-Andean tectonic lineament known asthe Calama?Olacapato?Toro (COT) fault system,which favours a high secondary permeability testifiedby the presence of numerous springs.This study presents new stratigraphic, structural andhydrogeological data on the geothermal field, togetherwith preliminary geochemical and magnetotelluricdata.Our data suggest that the main geothermal reservoir islocated within the Pre-Palaeozoic?Ordovicianbasement units, characterised by unevenly distributedsecondary permeability. The reservoir is recharged bymeteoric waters via infiltration in the ridges above4500 m a.s.l. The reservoir is covered by Miocene?Quaternary units that allow a local circulation ofshallow groundwater. Geothermal fluids upwell inareas with more intense fracturing, especially wheremain regional structures, particularly NW?SE COTparallellineaments, intersect with secondary structuresassociated with the development of the Tocomarbasin. Preliminary data indicate a reservoirtemperature of ~ 200 °C and a local geothermalgradient of ~ 130°C/km associated with theQuaternary volcanic activity in the Tocomar area.The integration of field-based and geophysicalanalyses proved to be effective in approaching theexploration of remote geothermal fields, and indeepening the conceptual model for geothermalcirculation.