New contributions into the chronostratigraphy of the Rincón de la Vieja volcano (Costa Rica) over the past 35,000 years

Abstract

We present a comprehensive geological mapping of the northern sector of the Rincón de la Vieja volcano, which includes the surveying of stratigraphic sections and new radiocarbon sampling, to provide an updated understanding of its volcanic history over the past 35,000 years. This study identifies a sequence of ancient lahars, lava flows, pyroclastic density currents (PDCs), and Plinian/sub-Plinian tephra fall deposits, with ages older than ~8,300 years BP, possibly sourced from the westernmost craters. Since then, an erosive unconformity suggests a significant period of explosive inactivity lasting at least 2,000 years. The most recent effusive event of importance occurred at around 5,300 years BP, forming the Gavilán lava field. A particularly noteworthy Plinian eruption, resulting in the Río Blanco Tephra sequence, deposited pumice to the west and southwest of the volcano and PDCs on its northern flank, extending up to at least 8.5 km. This explosive event, the largest in the last ~5,000 years, likely caused substantial modifications to the crater area, including its destruction and enlargement. Radiometric age data suggest that the Río Blanco event occurred at around 1650-1746 cal yr BP. This study enhances the understanding of the Late Pleistocene-Holocene eruption history of Rincón de la Vieja, providing valuable insights for volcanic hazard assessment and risk management.