A cool, nutrient-enriched eastern equatorial Pacific during the mid-Pleistocene transition

noaa-ocean-27050 Eastern Equatorial Pacific Nitrogen Data during the mid-Pleistocene Transition Robinson, R.S. Eastern Equatorial Pacific Nitrogen Data during the mid-Pleistocene Transition 2019-06-24 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/27050 Investigator R.S. Robinson earth science paleoclimate paleoceanography sample identification,null,null,null,null,paleoceanography,null,null,C,ODP sample identifier earth science paleoclimate paleoceanography delta 15N,sediment,null,per mil AIR,null,paleoceanography,null,isotope ratio mass spectrometry,N,null earth science paleoclimate paleoceanography nitrogen,sediment,null,percent,null,paleoceanography,null,elemental analysis,N,total nitrogen; weight percent earth science paleoclimate paleoceanography depth,null,null,meter,null,paleoceanography,null,null,N,meters composite depth; depth based on composite depth scale from Lawrence et al.(2006) earth science paleoclimate paleoceanography depth,null,null,meter,null,paleoceanography,null,null,N,meters below seafloor; depth based on shipboard depth scale earth science paleoclimate paleoceanography age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,age based on Lawrence et al. (2006) chronology earth science paleoclimate paleocean nitrogen isotopes geoscientificInformation 1234770 cal yr BP 59790 cal yr BP Complete -3.095 -3.095 -90.81833 -90.81833 -3296 -3296 Ocean Pacific Ocean South Pacific Ocean ODP 846>LATITUDE -3.095>LONGITUDE -90.81833 None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Robinson, R.S., C.A. Jones, R.P. Kelly, P. Rafter, J. Etourneau, and P. Martinez 2019 A cool, nutrient-enriched eastern equatorial Pacific during the mid-Pleistocene transition Geophysical Research Letters 46 10.1029/2018GL081315 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL081315

The emergence of high-amplitude, low-frequency glacial-interglacial cycles during the mid-Pleistocene climate transition (MPT; 800-1,200 ka) is associated with global cooling. In the eastern equatorial Pacific, sea surface temperatures cooled, and the upwelling-induced cold tongue expanded significantly during the MPT. Here we use sedimentary records of iron, biogenic silica, and nutrient-nitrogen consumption to evaluate biogeochemical changes hypothesized to accompany the cold tongue expansion. Our results suggest that the eastern equatorial Pacific of the MPT hosted surface waters with higher nitrate contents and biogenic silica production relative to the last 600 ka. Increased production occurred despite low iron supply. We attribute this to enhanced upwelling and nutrient enrichment of thermocline waters, both likely related to the northward migration of Southern Ocean fronts. The return of these fronts to their southward positions after the MPT may be associated with stronger drawdown of nutrients and, potentially, atmospheric CO2 in the Southern Ocean. STUDY NOTES: Measurement precision- %TN: 0.01%; d15N: 0.3 per mil. Provided Keywords: equatorial Pacific, upwelling, nitrogen isotopes, mid-Pleistocene transition

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2019/robinson2019-odp846.txt NOAA Template File; ODP 846 d15N and Total Nitrogen Data USA/NOAA DIF Version 9.8.4 2019-06-28 2019-06-28