noaa-ocean-5909 Dean and Arthur 1999 Atlantic DSDP L.Cretaceous CaCO3 Geochemistry Data Dean, W.E.; Arthur, M.A. Dean and Arthur 1999 Atlantic DSDP L.Cretaceous CaCO3 Geochemistry Data 1999-05-25 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/5909 Investigator W.E. Dean Investigator M.A. Arthur earth science paleoclimate paleocean geoscientificInformation 142000000 cal yr BP 112000000 cal yr BP Complete 12.4833 35.5 -75.6167 -20.05 -5117 -4633 Ocean Arctic Ocean DSDP 367>LATITUDE 12.4833>LONGITUDE -20.05 Ocean Atlantic Ocean North Atlantic Ocean DSDP 391C>LATITUDE 28.2333>LONGITUDE -75.6167 Ocean Atlantic Ocean North Atlantic Ocean DSDP 387>LATITUDE 32.3167>LONGITUDE -67.6667 Ocean Atlantic Ocean North Atlantic Ocean DSDP 105>LATITUDE 34.9>LONGITUDE -69.16 Ocean Atlantic Ocean North Atlantic Ocean DSDP 603B>LATITUDE 35.5>LONGITUDE -70.0333 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 Walter E. Dean and Michael A. Arthur 1999 Journal of Foraminiferal Research 29 4 465-486 http://jfr.geoscienceworld.org/content/29/4/465.abstract?sid=be70f778-6d57-480e-b0b5-d11154e61534 Tracy D. Frank, Michael A. Arthur and Walter E. Dean Journal of Foraminiferal Research 29 4 340-351 http://jfr.geoscienceworld.org/content/29/4/340.abstract

The stable isotope and minor element geochemistry of Neocomian (Lower Cretaceous) pelagic carbonates of the North Atlantic Basin (Deep Sea Drilling Project Sites 105, 367, 387, 391, and 603) was examined to develop a diagenetic model for pelagic limestones. In particular, we hoped to test the fidelity of whole-rock geochemical records as paleoceanographic indicators for pelagic deposits of pre-Aptian age, in which individual microfossils are not available for analysis. Data indicate that in addition to depth of burial, rhythmic variations in primary carbonate content have strongly controlled diagenetic patterns and associated geochemical signatures in these Neocomian sequences. Samples become increasingly depleted in Sr and delta 18 O with increasing CaCO 3 content. Within individual sedimentary sections, substantial decreases in Sr/Ca ratios and delta 18 O values are evident over a range of 4 to 98% CaCO 3 . However, even over a relatively narrow range of 50 to 98% CaCO 3 a 2.5 per mil variation in delta 18 O values and a change of a factor of 1.7 in Sr/Ca ratios are observed. Carbon isotope compositions do not vary as extensively with CaCO 3 content, but carbonate-rich intervals tend to be relatively depleted in 13 C. Petrographic analysis reveals that these geochemical patterns are related to the transfer of CaCO 3 from carbonate-poor intervals (calcareous shales and marlstones) to adjacent carbonate-rich intervals (limestones) during burial compaction and pressure solution. This process results in the addition of diagenetic cement to carbonate-rich intervals to produce a bulk composition that is relatively depleted in Sr and 18 O and, at the same time, enables the retention of more-or-less primary carbonate that is relatively enriched in Sr and 18 O in adjacent carbonate-poor intervals. Thus, although cyclic variations in CaCO 3 content are primary in the Neocomian sequences examined, measured variations in Sr/Ca ratios and delta 18 O values are not and, as such, do not provide reliable proxies for past variations in climate, oceanographic conditions, or global ice volume.

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