Biogenic Silica Data from the Indian Ocean sector of the Southern Ocean during the mid-Pleistocene climate transition Billups, K.; York, K.; Bradtmiller, L.I. Billups, K. York, K. Bradtmiller, L.I. earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,below sea floor) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,based on magnetostratigraphy using the ages of Ogg et al. (2012)) earth science/paleoclimate/paleoceanography (depth at sample end,null,null,centimeter,null,paleoceanography,null,null,N,depth at bottom of core section) earth science/paleoclimate/paleoceanography (sample identification,null,null,null,null,paleoceanography,null,null,C,core) earth science/paleoclimate/paleoceanography (sample identification,null,null,null,null,paleoceanography,null,null,N,section) earth science/paleoclimate/paleoceanography (sample identification,null,null,null,null,paleoceanography,null,null,C,hole) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,based on tuning of the biogenic silica to the d18O stack of Lisiecki and Raymo (2005)) earth science/paleoclimate/paleoceanography (biogenic silica,sediment,null,percent,null,paleoceanography,null,spectrophotometry,N,null) earth science/paleoclimate/paleoceanography (depth at sample start,null,null,centimeter,null,paleoceanography,null,null,N,depth at top of core section) earth science/paleoclimate/paleoceanography (sample identification,null,null,null,null,paleoceanography,null,null,N,site) earth science/paleoclimate/paleocean (ODP 745B>LATITUDE -59.616667>LONGITUDE 86.866667) We use biogenic silica (opal) mass accumulating rates (MARs) at Ocean Drilling Program Site 745B to infer upwelling, and by extension upper water column stratification, on glacial to interglacial time scales during the mid-Pleistocene climate transition (MPT; 1.2–0.6 Ma). Distinct variations in the percent biogenic silica content of the sediments parallel the global benthic foraminiferal d18O stack affording the derivation of an orbital-scale age model. Opal MARs confirm that silica production/preservation was indeed at a minimum at each of the glacial maxima during the entire MPT consistent with the late Pleistocene model that links upwelling of dissolved silica with water column stratification. A unique relationship between opal MARs and benthic foraminiferal d13C values in the South Atlantic suggests that during the midpoint of the MPT stratification may also be causally related to deep water circulation. However, there is no evidence that cooling during the MPT and the evolution of the 100 kyr climate cycle are linked to changes in water column stratification. Terrigenous sediment MARs, on the other hand, which can be inferred from the proportion of biogenic silica in the sediments at this particular site, provide evidence for increased glacial activity on Antarctica beginning with the onset of the MPT and culminating in a maximum during its midpoint (Marine Isotope Stage 22, 0.9 Ma). Thereafter, glacial activity decreases and we speculate that the evolution of the 100 kyr cycle is associated with a thickening ice sheet after reaching maximum extent somewhat analogous to the processes proposed for Northern Hemisphere ice sheets. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Billups, K. Investigator : York, K. Investigator : Bradtmiller, L.I. 2018-05-16 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/24090 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/billups2018/billups2018-745b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/billups2018/billups2018-745b.txt English https://www.ncdc.noaa.gov/paleo/study/24090 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/billups2018/billups2018-745b.txt Billups, K., K. York, and L.I. Bradtmiller2018Water column stratification in the Antarctic zone of the Southern Ocean during the mid-Pleistocene climate transitionPaleoceanography and Paleoclimatology3310.1029/2018PA003327 START YEAR: 1093000 cal yr BP * END YEAR: 643000 cal yr BP 86.866667 -59.616667 86.866667 -59.616667