Estudo da atividade hidrotermal no vulcão do Fogo (Cabo Verde) através da análise geoquímica de amostras de solo

ABSTRACT: Characterizing hydrothermal systems at volcanoes is particularly important as they play a crucial role in controlling eruptive dynamics. On the long term, hydrothermal systems participate in the geochemical alteration of both rocks and soils, through hydrolysis, dissolution, mineral precipitation, and secondary mineralization contributing in the gradual destabilization of volcanic structures. Fogo volcano (Cape Verde) is the most active volcano in he eastern Atlantic. It features a fumarolic field and passive degassing in its summit crater. A total of 65 soil samples were collected and analyzed, 4 years after the 2014-2015 eruption, in the area surrounding the volcanic edifice including the last eruptive vent with the main objective of detecting and identifying the geochemical and mineralogical signature of hydrothermal activity. Preliminary results show that soil samples were enriched in Ca, Cu, Co, Fe, Na, P, and Ti, when compared to 2014-2015 lava flows, which is confirmed by principal component analysis. Distribution of geochemical elements clearly reflects the mineral phases and is discussed together with geophysical data to shed the light on hydrothermal processes taking place at Pico do Fogo.