Gastaldello, Maria Elena; Agnini, Claudia; Westerhold, Thomas; Drury, Anna Joy; Alegret, Laia (2024): Age model, carbonate mass accumulation rates and benthic foraminifera from ODP Site 175-1085 [dataset bundled publication]. PANGAEA, https://doi.org/10.1594/PANGAEA.962075

We conducted a study on the Late Miocene-Early Pliocene Biogenic Bloom, a phase of increased marine biological productivity that occurred approximately between 9 and 3.5 Ma. This phenomenon was observed worldwide in various ocean locations and was attributed to either a rise in nutrient input or a significant reorganization of nutrients within the oceans. Our focus was on the Biogenic Bloom at Ocean Drilling Program (ODP) Site 1085 in the Atlantic Ocean. We provided new biostratigraphic data to develop an updated age model and subsequently examined the variations observed in benthic foraminiferal assemblages throughout the Biogenic Bloom. At Site 1085, the Biogenic Bloom occurred between 8.1 and 3.0 Ma and we studied it employing various proxies, including linear sedimentation rates, carbonate mass accumulation rates, benthic foraminifera assemblage data and associated indexes (such as benthic foraminifera accumulation rate and diversity). We identified four distinct intervals within the Biogenic Bloom based on paleoenvironmental changes inferred from the benthic foraminiferal assemblages. Two intervals within the Biogenic Bloom, spanning from 8.1 to 5.2 Ma and from 3.8 to 3.0 Ma, indicated oligotrophic conditions with highly seasonal phytoplankton blooms. Between 5.2 and 4.8 Ma, we observed short-term fluctuations between well-oxygenated oligotrophic conditions and phases of low-oxygen eutrophic conditions. From 4.8 to 3.8 Ma, we noted a transition to a higher input of food supply to the seafloor. Our findings indicate that the onset of the Biogenic Bloom coincided with well-dated global records and its conclusion aligned with other records from the Atlantic Ocean. Furthermore, our research supports the hypothesis that the Biogenic Bloom should not be viewed as a single productivity event but rather as a complex occurrence comprising several shorter-lived high-productivity periods driven by different factors.