Subantarctic Atlantic 1.1Ma Dust, Iron and Productivity Reconstructions Martínez-Garcia, A.; Rosell-Melé, A.; Geibert, W.; Gersonde, R.; Masqué, P.; Gaspari, V.; Barbante, C. Martínez-Garcia, A. Rosell-Melé, A. Geibert, W. Gersonde, R. Masqué, P. Gaspari, V. Barbante, C. Sea Surface Temperature Reconstruction sensitivity earth science/paleoclimate/paleoceanography (232Th,sediment,null,parts per million,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (iron,sediment,null,milligram per square meter per year,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (alkenone,sediment,null,parts per billion,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (230Th excess,sediment,null,disintegration per minute per gram,null,paleoceanography,null,null,N,excess fraction) earth science/paleoclimate/paleoceanography (iron,sediment,null,milligram per square meter per year,null,paleoceanography,null,null,N,mass accumulation rate) earth science/paleoclimate/paleoceanography (uranium,sediment,null,disintegration per minute per gram,null,paleoceanography,null,null,N,authigenic) earth science/paleoclimate/paleoceanography (n-alkane,sediment,null,parts per billion,null,paleoceanography,null,null,N,C23 - C33 alkanes) earth science/paleoclimate/paleoceanography (n-alkane,sediment,null,microgram per square meter per year,null,paleoceanography,null,null,N,mass accumulation rate) earth science/paleoclimate/paleoceanography (iron,sediment,null,parts per million,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (iron,sediment,null,percent,null,paleoceanography,null,null,N,iron fraction in dust) earth science/paleoclimate/paleoceanography (mineral matter,sediment,null,gram per square meter per year,null,paleoceanography,null,null,N,dust flux) earth science/paleoclimate/climate reconstructions|paleoceanography (sea surface temperature,alkenone unsaturation index,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (alkenone,sediment,null,microgram per square meter per year,null,paleoceanography,null,null,N,mass accumulation rate) earth science/paleoclimate/paleoceanography (rhenium,sediment,null,parts per million,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (mineral matter,sediment,null,percent,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (aluminum,sediment,null,parts per million,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean (PS2489-2>LATITUDE -42.8733>LONGITUDE 8.9733) (ODP 1090>LATITUDE -42.908333>LONGITUDE 8.9) Paleoclimatic reconstructions have provided a unique data set to test the sensitivity of climate system to changes in atmospheric CO2 concentrations. However, the mechanisms behind glacial/interglacial (G/IG) variations in atmospheric CO2 concentrations observed in the Antarctic ice cores are still not fully understood. Here we present a new multiproxy data set of sea surface temperatures (SST), dust and iron supply, and marine export productivity, from the marine sediment core PS2489-2/ODP Site 1090 located in the subantarctic Atlantic, that allow us to evaluate various hypotheses on the role of the Southern Ocean (SO) in modulating atmospheric CO2 concentrations back to 1.1 Ma. We show that Antarctic atmospheric temperatures are closely linked to changes in SO surface temperatures over the last 800 ka and use this to synchronize the timescales of our marine and the European Project for Ice Coring in Antarctica (EPICA) Dome C (EDC) records. The close correlation observed between iron inputs and marine export production over the entire interval implies that the process of iron fertilization of marine biota has been a recurrent process operating in the subantarctic region over the G/IG cycles of the last 1.1 Ma. However, our data suggest that marine productivity can only explain a fraction of atmospheric CO2 changes (up to around 40–50 ppmv), occurring at glacial maxima in each glacial stage. In this sense, the good correlation of our SST record to the EDC temperature reconstruction suggests that the initial glacial CO2 decrease, as well as the change in the amplitude of the CO2 cycles observed around 400 ka, was most likely driven by physical processes, possibly related to changes in Antarctic sea ice extent, surface water stratification, and westerly winds position. STUDY NOTES: Sea surface temperature (SST), dust, iron and marine export production reconstructions from the Subantarctic Atlantic covering the past 1.1 million years. Proxies include alkenones, n-alkanes, Fe, Al, Re and Uranium and Thorium isotopes. Two cores from the central part of the Subantarctic Zone (ODP Site 1090 and PS2489-2) were sampled in order to obtain a continuous record of the Pleistocene following the approach described by Becquey and Gersonde [2002]. Alkenones and n-alkanes were analyzed by GC-FID, and the UK37 paleotemperature index was used to estimate SST. Fe, Al, 232Th/230Th, U isotopes, and Re concentrations were determined by Inductively Coupled Plasma Sector-Field Mass Spectrometry. 230Thex was calculated using a 232Th/238U activity ratio of 0.4, and a 234U/238U activity ratio in the lithogenic end-member of 0.9. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Martínez-Garcia, A. Investigator : Rosell-Melé, A. Investigator : Geibert, W. Investigator : Gersonde, R. Investigator : Masqué, P. Investigator : Gaspari, V. Investigator : Barbante, C. 2011-01-12 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10353 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.xls English https://www.ncdc.noaa.gov/paleo/study/10353 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/martinez-garcia2009/martinez-garcia2009.xls Martínez-Garcia, A., A. Rosell-Melé, W. Geibert, R. Gersonde, P. Masqué, V. Gaspari, and C. Barbante. 2009. Links between iron supply, marine productivity, sea surface temperature, and CO2 over the last 1.1 Ma. Paleoceanography, 24, PA1207, doi:10.1029/2008PA001657. START YEAR: 1085940 cal yr BP * END YEAR: 0 cal yr BP 8.9 -42.908333 8.9733 -42.8733