Late Miocene to Pliocene calcareous nannofossil assemblage records and paleotemperature gradients from the NW Australian shelf (IODP Sites U1463, U1464)

IODP Expedition 356 drilled on the northwestern (NW) Australian shelf, recovering Miocene-Pleistocene sediments in an area where climate archives are scarce. In this work we investigated cores from two sites that are situated in two adjacent basins (IODP Site U1463 and U1464). Our analysis includes astronomically tuned records of relative abundance (%) and accumulation rates (N/cm² kyr) of the most common calcareous nannofossil species, estimates of the Shannon diversity index, as well as a ratio between dominant taxonomic groups termed the nannofossil stratification index (NSI) . Additionally, paleotemperature gradients between the NW Australian shelf area and the eastern Indian Ocean were calculated from previously published records. All the above records were used to reconstruct regional ocean circulation patterns, the relative intensity of seasonally flowing boundary currents, as well as changes in paleoproductivity and species dominance in the area between 6-3.5 million years ago (Ma).