The Alpine orogeny was the main cause of extensive tectonic activities and it was responsible for the formation of the hydrothermal field within the region. The Chaves graben was formed by the relative motion of the block with different types of sediments being settled. The most recent formations are a sedimentary series (lacustrine, alluvial, colluvial, detritic, etc.) with variable thickness that had their origin during the Miocene. Two main faults cross and influence the tectonic activities: the north-northeast by south-southeast Chaves-Verin Fault and a fault system crossing near Faiões and Santo Estêvão. The first fault developed from late Hercynian tectonic episode occurring between 280 and 300 million years ago, that developed into an almost north-south direction into the lithosphere. Intense neotectonic activity reactivated these old fractures, originating in a complex pattern of faults in the sedimentary basin.