PONTE, D., WALLENSTEIN, N., DUNCAN, A. (2020) - Eruptive sequences of Fogo and Furnas volcanoes between Ribeirinha and Lomba da Maia (São Miguel, Azores). Comunicações Geológicas, 107, Especial I, 17-20, ISSN: 0873-948X; e-ISSN: 1647-581X.

​The documentation of exposures of volcanic products in the north coast of São Miguel Island (Azores), between Ribeirinha and Lomba da Maia, allowed to improve the knowledge of the eruptive sequences of the northern flanks of Fogo and Furnas volcanoes. Three main volcano-stratigraphic units were defined, based on spatial-temporal criteria, and the study was mainly focused on the products of subaerial explosive eruptions. At Santa Iria port (Ribeirinha) and at Viola beach (Lomba da Maia) important ignimbrites were observed and integrated in the Base Unit. In the Intermediate Unit the new São Brás Formation was defined and new stratigraphic data allowed to complement Porto Formoso, Chã das Gatas and Coroa da Mata formations. The Chã das Gatas Formation was subdivided into Calhau do Cabo and Defeira sequences, allowing to constrain the age of the Defeira Sequence between 21,340 and 18,600 years B.P. The deposits of the last 5,000 years were included in the Recent Unit.