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Radiocarbon dates for lava flows and pyroclastic deposits on Sao Miguel, Azores

January 1, 1991

We report 63 new radiocarbon analyses of samples from Sao Miguel, the largest island in the Azores archipelago. The samples are mainly carbonized tree roots and other plant material collected from beneath 20 mafic lava flows and spatter deposits and from within and beneath 42 trachytic pyroclastic flow, pyroclastic surge, mudflow, pumice-fall and lacustrine deposits and lava flows. One calcite date is reported. These dates establish ages for 48 previously undated lava flows and pyroclastic deposits, and revise three ages previously reported. These data are critical to deciphering the Holocene and late Pleistocene eruptive history of Sao Miguel and evaluating its potential volcanic hazards. Average dormant intervals during the past 3000 years are about 400 years for Sete Cidades volcano, 145 years for volcanic Zone 2, 1150 years for Agua de Pau volcano and 320 years for Furnas volcano. No known eruptions have occurred in volcanic Zone 4 during the past 3000 years. -from Authors

Citation Information

Publication Year 1991
Title Radiocarbon dates for lava flows and pyroclastic deposits on Sao Miguel, Azores
DOI
Authors R. B. Moore, M. Rubin
Publication Type Article
Publication Subtype Journal Article
Series Title Radiocarbon
Series Number
Index ID 70015018
Record Source USGS Publications Warehouse
USGS Organization