| Abstract |
The Pico Alto Geothermal Field (PAGF) is emplaced on a high volcanological complexity area in the central part of Terceira Island (Azores archipelago, Portugal), where Pico Alto and Guilherme Moniz silicious polygenetic volcanoes with caldera and the Basaltic Fissural Zone formations outcrop and interact. At depths, the geothermal system interacts also with the Santa Bárbara central volcano with nested caldera formations that outcrop further east. Through information from a detailed 1:10,000 geological mapping and new insights on the associated surface geology, volcanostratigraphy, morpho-tectonics and absolute ages on the PAGF and its surrounding areas, this work presents relevant geologic and volcanological inputs to the building up of a comprehensive and robust conceptual model to the Pico Alto Geothermal Field, where a pilot geothermal power plant 3.5 MW is under construction and should be running in the first semester of 2017. To built up a well constrained and robust conceptual model, the geologic mapping and interpretative profiles produced were coupled with temperature distribution, AMT anomalies, geophysic (e.g. microgravimetric), boreholes data (cuttings, lithological logs) and hydrogeological characterization of the deep geothermal system. This integrated, multi-disciplinary approach to understand the “plumbing” of the Pico Alto Geothermal Field also raised relevant key issues about the deep geology of Terceira Island and the evolution of its active central volcano systems, Santa Bárbara and Pico Alto, the latest silicious in composition and the younger volcanic centre of Terceira Island. The geosciences data gathered about the PAGF are considered essential information within the framework of the IMAGE Project (Integrated Methods for Advanced Geothermal Exploration) to built a 3D model representation and visualization of this geothermal system. |