Astronomical pacing and abrupt changes in North Atlantic biogenic sedimentation during the latest Miocene and Early Pliocene: the IODP Site U1562 case study

Abstract

The latest Miocene and Early Pliocene (7-3.6 Ma) include key paleoclimatic and paleoceanographic events such as the Messinian Salinity Crisis (MSC), the late Miocene to Pliocene biogenic bloom (hereafter referred as “biogenic bloom”) and its potential termination, as well as the warm early Pliocene, a commonly used analogue for future global warming. Limited information exists regarding how these events impacted North Atlantic ocean circulation and carbonate sedimentation, mainly due to the lack of continuous, high-resolution records in high latitudes. During the summers of 2021 and 2023, the International Ocean Discovery Program (IODP) Expeditions 395C and 395 drilled a transect of five sites in the North Atlantic (at ~60°N). Preliminary results indicate that IODP Site U1562 has continuous sediment recovery, significant variations in carbonate content, as well as good preservation of calcareous fossils across the latest Miocene to Pliocene, making it a suitable candidate for high-resolution paleoclimatic reconstructions. Here, we estimate carbonate sedimentation and paleoproductivity for this site using high-resolution X-Ray fluorescence (XRF) records, derived from elemental intensities measured in core half-sections. Ratios between biogenically derived and detrital elements reveal the orbitally controlled pacing of carbonate production/deposition, as well as a stepwise, sustained decrease in biogenic sedimentation that occurred during the early Pliocene. The latter shift could have been linked to ocean current reorganizations related to the termination of the MSC or the “biogenic bloom”. Finally, we use a cyclostratigraphic approach to explore the possibility of building an astronomically tuned age model for this site using the XRF records.