Age model, carbonate mass accumulation rates and benthic foraminifera from IODP Site 363-U1488

The Biogenic Bloom is a paleoceanographic phenomenon marked by elevated marine biological productivity that occurred from the Late Miocene to the Early Pliocene (approximately 8 to 3.5 million years ago). We investigated the Biogenic Bloom at International Ocean Discovery Program (IODP) Site 363-U1488 in the western equatorial Pacific Ocean. Semi-quantitative analyses of calcareous nannofossils were performed on 33 samples. Calcareous nannofossil biostratigraphic data, integrated with shipboard data, were used as tie points to develop the age model of the study section. A quantitative study of benthic foraminiferal assemblages was conducted on 39 samples, identifying 90 taxa grouped into infaunal and epifaunal morphogroups. All identified species were assigned to Oxic, Suboxic, and Dysoxic groups to calculate the Enhanced Benthic Foraminifera Oxygen Index (EBFOI). We also calculated the benthic foraminiferal accumulation rates (BFAR) to estimate export productivity. The Biogenic Bloom was identified by the increase in carbonate mass accumulation rates documented between 8.1 and 4.0 million years ago. We identified four distinct intervals within the Biogenic Bloom based on paleoenvironmental changes inferred from the benthic foraminiferal assemblages.