Database for reconstruction of atmospheric CO2 in the Milankovitch Chron: Readme file ----------------------------------------------------------------------- NOAA Paleoclimatology Program and World Data Center A for Paleoclimatology ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Database for reconstruction of atmospheric CO2 in the Milankovitch Chron CONTRIBUTOR: W. H. Berger, Scripps Institution of Oceanography, UCSD, wberger@ucsd.edu IGBP PAGES/WDCA Data Contribution Series #: 96-031 SUGGESTED DATA CITATION: Berger, W.H., 1996, Database for reconstruction of atmospheric CO2 in the Milankovitch Chron, IGBP PAGES/World Data Center-A for Paleoclimatology Data Contribution Series # 96-031. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: W.H.Berger, T.Bickert, M.K.Yasuda, G.Wefer, 1996. Reconstruction of atmospheric CO2 from ice-core data and the deep-sea record of Ontong Java plateau: the Milankovitch chron. Geologische Rundschau 85:466-495. See also bibliography in file CO2REFS.TXT. LAST UPDATE: 12/96 (Original Receipt at WDCA Paleo) GEOGRAPHIC REGION: Global PERIOD OF RECORD: 3-750KYrBP LIST OF FILES: Text and Microsoft Excel files, Berger1996.Readme (this file), mila1000.txt, barnjoux.txt, co2refs.txt, 806isotp.txt, 806isotp.xls, ojc13p96.txt, ojc13p96.xls, sac18dat.txt, sac18dat.xls, co2recon.txt, co2recon.xls, ojsl96.txt, ojsl96.xls, ojsox96p.txt, ojsox96p.xls. DESCRIPTION: Data base for reconstruction of atmospheric CO2 in the Milankovitch Chron Data from the following cores were used in this study: ODP806B [1H, 2H, 3H] (00¯19.1'N, 159¯21.7'E, 2520m), ODP805C [1H, 2H] (01¯13.7'N, 160¯31.8'E, 3188m), DSDP586 [1H, 2H, 3H] (00¯29.8'S, 158¯29.9'E, 2218m), ERDC84p/pg (01¯25.3'N, 157¯15.3'E, 2339m), ERDC89p (00¯00.2'S, 155¯51.9'E, 1936m), ERDC93p (02¯14.5'S, 157¯00.5'E), ERDC113p (01¯38.1'S, 159¯13.2'E, 2158m), RNDB74 (00¯20.4'N, 159¯22.7'E, 2604m). There are seven tables, containing the following information: 1. Files Mila1000.txt and Mila1000.xls Milankovitch template Mila1000, for dating of deep-sea Î18O records, by correlation. Mila1000 is derived from numerical integration of Equation (1) which tracks ice volume through time: SL/t = GRO - INS**a * ICE**b * MEM[L]**c Here SL/t describes sealevel change, GRO is maximum ice buildup (which is taken to be constant), INS is the insolation in July, at 65¯N, ICE is the current ice mass subject to destruction, MEM is the average of such ice mass taken over time period L, and a, b, c, are exponents set for best fit. Calculations are in normalized space (0 to 1). Mila1000 is two thirds the model with the settings gro=0.025, a=4, b=1, c=4[L=57] and one third the model with gro=0.03, a=4, b=4, c=0. (The latter model emphasizes information in the precessional band.) 2. Files sac18dat.txt and sac18dat.xls Oxygen isotope records from Ontong Java Plateau (G. sacculifer, 350-420 Êm). Sources: 806B, Berger et al. (1993a) (analyses Bremen); RNDB74, this work (analyses Bremen); ERDC84, ERDC89, ERDC113, Schiffelbein (1984) (analyses S.I.O.); ERDC93, Wu and Berger (1991) (analyses S.I.O.). All records are here re- dated using template Mila1000 (Table A1). 3. Files OJsox96p.txt and OJsox96p.xls Oxygen isotope record OJsox96: stack for Ontong Java Plateau (G. sacculifer, late Quaternary). Sources as for Table A2, with the addition of information from ODP805C (Berger et al., 1993b), DSDP586 (unpublished), and ODP807 (Prentice et al., 1993). All records re-dated using template Mila1000 (Table A1). Stacked record Fourier filtered to exclude periods < 8 kyr. 4. Files OJsl96.txt and OJsl96.xls Sea level model OJsl96, for the Brunhes Chron. Based on Mila1000 (Table A1) and OJsox96 (Table A3), standardized, averaged, and re-set to the sealevel range of the last 20 kyr (taken as 123 m). 5. Files 806isotp.txt and 806isotp.xls Isotope stratigraphy of ODP806B, with data from Berger et al. (1993a), Bickert et al. (1993), Schmidt et al. (1993), and additions from unpublished analyses, for filling gaps, and for extending coverage. Extended coverage refers to P. wuellerstorfi, for depths below 14 mbsf (analyses in Bremen). 6. Files ojc13p96.txt and ojc13p96.xls Carbon isotope stratigraphy for Ontong Java Plateau, based on merging data from ODP806B, ODP805, DSDP586, and RNDB74. Data sources: Schmidt et al. (1993) for planktonic foraminifers in ODP806B (with some additions), Bickert et al. (1993) for benthic foraminifers in ODP806B and ODP805C (with extension beyond Milankovitch Chron). Data for DSDP586 and RNDB74: unpublished. 7. Files co2recon.txt and co2recon.xls Reconstructed values for atmospheric CO2 using multiple regression derived from comparing deep-sea data with the Vostok CO2 record published in Barnola et al. (1987), after re-dating the Vostok record by correlating ice-core deuterium to deep-sea Î18O, or by correlating ice-core atmospheric Î18O to deep-sea Î18O, as appropriate for each transform equation. Each equation has the form CO2 = constant + a*x1 + b*x2 + ... Four transforms were used, containing the following terms in addition to a constant: 1) oj**2, oj'**2; 2) imb**2, imb'**2; 3) oj**2, [p13-w13]**2; 4) oj**3, oj'**2, ir', ir'**2. Parameter oj is sea level model OJsl96, set for positive Î18O values, imb is the SPECMAP series for the last 650 kyr, set similarly, [p13-w13] is Î13C between P. obliquiloculata and P. wuellerstorfi, and ir is insolation in May at 65¯N, set to an average of 0.75 and std.dev. of 0.25 (data from Berger and Loutre, 1991). The average of four estimates is re-regressed on the Vostok data, using ages derived from correlating ice-core deuterium with OJsl96. The local range of the estimate is taken as 2 standard deviations centered on the original mean of the four estimates.