GISP2/GRIP Reconstructed Ages for Disturbed Bottom Sections ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: GISP2/GRIP Reconstructed Ages for Disturbed Bottom Sections LAST UPDATE: 5/2007 (Original receipt by WDC Paleo) CONTRIBUTOR: Makoto Suwa and Michael Bender, Princeton University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2007-050 SUGGESTED DATA CITATION: Suwa, M., et al. 2007. GISP2/GRIP Reconstructed Ages for Disturbed Bottom Sections. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2007-050. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Suwa, M., J.C. von Fischer, M.L. Bender, A. Landais, and E.J. Brook. 2006. Chronology reconstruction for the disturbed bottom section of the GISP2 and the GRIP ice cores: Implications for Termination II in Greenland. Journal of Geophysical Research, Vol. 111, D02101, doi:10.1029/2005JD006032. ABSTRACT: We have reconstructed chronology for the disturbed bottom parts of the GRIP and GISP2 ice cores using the combined paleoatmospheric records of CH4 concentration and d18Oatm in the trapped gases. Our reconstructed ages for basal ice samples are based on comparison of published measurements of CH4 and d18Oatm from the disturbed section of the GRIP and GISP2 cores with the same properties in the Vostok ice core. NGRIP d18Oice values are also used to constrain the chronology during the end of marine isotope stage 5e. For each sample, we assign an age that represents the unique or most probable time of gas trapping, given its gas composition. Of 157 samples with CH4 and d18Oatm data, 10 give unique ages. Twenty-five newly measured values of the triple isotope composition of O2 from the disturbed section of the GISP2 core add a third time-dependent gas property that agrees with our reconstruction. Our reconstruction supports earlier conclusions of Landais et al. (2003) that the disturbed section primarily includes ice from the last interglacial (MIS 5e) and the penultimate glacial period (MIS 6). The oldest ice in the basal layer of GISP2 and GRIP has an age >=237 ka. The climate history we derive suggests that the last interglacial at Summit, Greenland, around 127 ka was slightly warmer than the current interglacial period. Reduction of various ion concentrations in ice and thickening of the ice sheet during Termination II was similar to that in Termination I. ADDITIONAL REFERENCES FOR GAS RECORDS: Bender, M., T. Sowers, M.-L. Dickson, J. Orchardo, P. Grootes, P. Mayewski, and D. Meese. 1994. Climate connections between Greenland and Antarctica during the last 100,000 years. Nature, 372, 663-666. Chappellaz, J., E. Brook, T. Blunier, and B. Malaize. 1997. CH4 and d18O of O2 records from Antarctic and Greenland ice: A clue for stratigraphic disturbance in the bottom part of the Greenland Ice Core Project and the Greenland Ice Sheet Project 2 ice cores. Journal of Geophysical Research, 102(C12), 26,547-26,557. Landais A., J.Chappellaz, M. Delmotte, J. Jouzel, T. Blunier, C. Bourg, N. Caillon, S. Cherrier, B. Malaize, V. Masson-Delmotte, D. Raynaud, J. Schwander, and J.P. Steffensen. 2003. A tentative reconstruction of the last interglacial and glacial inception in Greenland based on new gas measurements in the Greenland Ice Core Project (GRIP) ice core. Journal of Geophysical Research, 108 (D18), 4563, doi: 10.1029/2002JD003147. GEOGRAPHIC REGION: Greenland PERIOD OF RECORD: 248 - 102 KYrBP FUNDING SOURCES: Gary Comer Foundation, US National Science Foundation Office of Polar Programs. DESCRIPTION: GISP2/GRIP Reconstructed Ages for Disturbed Bottom Sections Summit, Greenland. Core locations: GISP2 72o35'N 38o28'W GRIP 72o35'N 37o38'W DATA: 1. GISP2 Ice core Column 1: Core depth (m) Column 2: CH4 (ppbv) Column 3: d18O of paleoatmospheric O2 (permil) Column 4: d18O of ice (permil) Column 5: Best estimate ages - ice age (ka) Column 6: Best estimate ages - gas age (ka) Column 7: *u indicates that is is an uniquely dated sample Depth CH4 d18Oatm d18Oice IceAge GasAge Uniq. 2754 584.8 0.01 -38.0 234.6 234.2 2756 496.9 0.11 -39.0 168.0 167.5 2758 569.5 0.01 -36.1 233.7 233.3 2764 444.3 0.58 -38.8 148.4 147.9 2772 506.4 0.58 -36.1 108.0 107.7 2780 476.8 0.68 -38.0 113.0 112.6 2788 497.8 0.54 -38.5 187.6 187.1 2796 491.1 0.68 -37.8 112.3 111.8 2804 632.6 0.53 -39.4 238.3 237.7 *u 2808 495.0 0.64 -40.3 228.5 227.7 2818 634.0 0.43 -36.9 237.7 237.3 2826 619.0 0.23 -37.2 105.3 105.0 2834 630.0 0.24 -38.9 105.7 105.2 2842 638.0 0.23 -33.2 202.7 202.4 2849.9 545.0 0.49 -37.8 115.1 114.6 2858 536.5 0.51 -37.4 115.2 114.8 2866 566.5 0.41 -37.2 116.0 115.7 2874 579.5 0.31 -37.9 179.1 178.7 2882 556.0 0.56 -37.7 114.8 114.4 2890 488.0 0.35 -39.0 165.1 164.5 2898 473.0 0.84 -40.0 156.5 155.8 2906 466.0 0.88 -41.2 154.0 153.0 2913.9 460.5 0.65 -39.6 163.5 162.9 2926 517.0 0.71 -39.7 186.8 186.1 2927.9 527.2 0.72 -40.7 186.7 185.9 2930 456.5 0.69 -40.1 163.5 162.7 2931.9 411.5 0.79 -40.5 160.7 159.9 2933.9 442.7 0.31 -40.3 165.1 164.3 2937.9 417.8 0.89 -39.8 137.5 136.8 2940 336.5 0.96 -40.7 139.3 138.4 *u 2942 431.7 0.60 -39.6 148.4 147.7 2944.01 473.5 0.58 -40.1 188.0 187.3 2946 468.5 0.36 -39.1 191.3 190.7 2947.9 429.5 0.50 -39.7 248.1 247.5 2950 609.0 0.04 -35.8 104.3 104.0 2952 642.5 0.18 -33.0 127.2 126.9 2955.9 668.8 -0.24 -32.0 122.2 122.0 2958 648.5 0.18 -32.1 127.1 127.0 2960 713.5 -0.17 -33.2 125.9 125.7 *u 2962 679.5 0.21 -35.0 127.3 127.1 2964 490.0 0.72 -40.3 163.6 162.8 2966 527.0 0.47 -39.4 208.4 207.8 2968 492.5 0.63 -40.3 163.8 163.0 2970 605.5 0.29 -37.0 105.7 105.4 2972 421.0 0.22 -39.6 165.4 164.8 2974 462.0 0.18 -35.5 165.7 165.4 2975.9 622.5 0.02 -32.3 213.6 213.4 2978 623.0 0.06 -32.0 200.9 200.7 2980 729.5 -0.24 -31.7 125.7 125.6 *u 2982 644.0 0.16 -32.3 127.1 126.9 2983.9 659.3 0.04 -32.3 126.9 126.7 2986 629.0 0.18 -33.8 117.7 117.5 2988 627.0 0.05 -32.5 200.9 200.7 2990 670.0 0.02 -33.8 126.9 126.7 2992 692.5 -0.05 -32.4 126.6 126.4 *u 2993.9 636.5 0.20 -33.2 127.2 127.0 2996 518.0 0.36 -39.0 210.5 209.9 2997.95 641.4 -0.16 -31.6 120.7 120.6 3000 613.0 0.27 -33.6 116.9 116.7 3002 689.5 -0.11 -31.6 126.5 126.4 *u 3004 540.5 0.26 -35.6 178.0 177.7 3006 692.5 0.56 -36.5 238.4 238.0 *u 3008 569.0 0.51 -34.8 114.8 114.5 3009.9 632.7 0.33 -34.4 116.9 116.7 3012 627.5 0.45 -36.2 237.7 237.4 3013.9 449.6 0.56 -38.3 247.6 247.2 3016 632.0 0.67 -36.6 238.7 238.4 3020 633.0 0.43 -36.3 237.6 237.3 3021.91 697.4 0.46 -35.8 128.3 128.0 3024 639.0 0.51 -36.5 237.9 237.6 *u 3026 629.0 0.40 -33.8 116.3 116.0 3027.9 598.1 0.61 -36.7 180.8 180.5 3030 604.0 0.50 -38.5 180.5 180.0 3032 503.5 0.55 -37.7 107.7 107.3 2. GRIP Ice core Column 1: Core depth (m) Column 2: CH4 (ppbv) Column 3: d18O of paleoatmospheric O2 (permil) Column 4: d18O of ice (permil) Column 5: Best estimate ages - ice age (ka) Column 6: Best estimate ages - gas age (ka) Column 7: *u indicates that is is an uniquely dated sample Depth CH4 d18Oatm d18Oice IceAge GasAge Uniq. 2751.46 511.6 0.03 -38.5 102.7 102.2 2763.09 430.6 0.72 -38.0 113.0 112.6 2773.21 424.0 0.67 -38.7 113.1 112.6 2780.98 434.7 0.67 -38.8 113.0 112.5 2783.65 459.7 0.78 -38.7 111.8 111.3 2785.15 446.2 0.81 -37.8 113.0 112.6 2786.47 471.9 0.67 -37.6 109.1 108.7 2789 556.5 0.46 -34.1 180.0 179.8 2789.1 552.2 0.52 -34.2 114.7 114.5 2791.99 545.6 0.36 -34.3 116.2 116.0 2793.63 541.3 0.46 -34.3 114.8 114.5 2795.6 565.2 0.44 -32.4 203.7 203.5 2796.35 637.0 0.16 -32.6 127.2 127.0 2799.13 533.4 0.46 -34.7 116.1 115.8 2800.14 479.9 0.69 -35.3 109.3 109.0 2800.79 480.3 0.64 -35.3 109.0 108.7 2803.54 534.7 0.50 -35.3 114.8 114.5 2804.95 452.4 0.86 -37.3 182.1 181.7 2806.76 440.4 0.61 -38.2 107.9 107.4 2808 456.5 0.75 -38.1 112.4 111.9 2809.58 589.3 0.02 -32.1 212.2 212.0 2810.1 603.8 -0.02 -32.6 117.9 117.7 2811.55 578.5 0.18 -32.1 202.7 202.5 2812 608.9 -0.03 -32.2 126.8 126.6 2815.95 516.5 0.61 -35.2 114.5 114.2 2817.29 543.2 0.55 -34.5 114.7 114.4 2819.49 508.1 0.60 -35.7 109.2 108.9 2822 458.3 0.72 -37.1 113.0 112.6 2822.23 469.2 0.62 -37.0 108.3 108.0 2824.75 455.7 0.60 -36.4 107.9 107.6 2826.66 460.4 0.74 -36.7 111.5 111.2 2829.93 467.6 0.64 -36.3 108.5 108.2 2832.59 445.6 0.80 -37.2 112.9 112.6 2834.1 444.7 0.80 -37.4 113.0 112.6 2835.35 440.4 0.72 -37.8 113.0 112.6 2837.63 595.3 0.06 -32.2 201.5 201.3 2838.5 595.0 -0.02 -31.7 214.3 214.2 2838.7 600.9 -0.05 -31.8 126.8 126.6 2839.6 613.2 -0.10 -32.5 126.6 126.5 2839.94 680.6 -0.03 -32.2 N/A N/A 2840.25 598.6 -0.05 -32.0 201.3 201.1 2841.48 575.0 0.26 -32.5 203.2 203.0 2842 556.0 0.25 -32.0 203.4 203.2 2843.06 587.3 0.14 -31.9 201.7 201.5 2843.7 594.1 0.07 -31.7 201.5 201.3 2844.18 610.2 -0.03 -31.7 126.8 126.6 2844.78 594.8 0.02 -32.0 214.0 213.8 2845.2 570.6 0.05 -32.0 200.9 200.7 2846.1 598.5 -0.12 -32.1 120.6 120.5 2848.4 604.0 0.00 -31.6 126.8 126.6 2848.5 603.8 0.07 -31.7 202.1 201.9 2850.05 607.0 -0.13 -31.8 120.5 120.4 2850.75 607.3 0.03 -32.1 202.0 201.8 2851.59 637.6 -0.16 -33.9 126.5 126.3 2853.35 608.5 0.04 -34.8 104.5 104.3 2854.14 639.7 0.56 -35.3 238.3 238.0 *u 2856.1 606.5 -0.01 -31.8 126.8 126.6 2856.31 615.5 -0.01 -32.0 126.8 126.6 2857.1 607.9 -0.09 -32.0 126.7 126.5 2857.44 605.4 -0.04 -32.9 117.9 117.7 2859.95 613.6 -0.21 -32.1 122.2 122.0 2860.4 648.9 -0.17 -31.8 126.0 125.9 *u 2860.6 615.6 -0.06 -31.7 126.7 126.5 2861.15 618.2 0.13 -32.4 127.1 126.9 2864.45 521.7 0.41 -35.8 116.0 115.7 2866.55 615.5 0.31 -38.2 105.6 105.2 2880.85 414.4 0.11 -39.3 166.1 165.5 2882.2 373.8 0.65 -41.1 143.5 142.5 2897.55 477.6 0.83 -40.3 184.1 183.3 2900.87 364.4 0.69 -40.1 142.6 141.9 2904.6 427.1 0.18 -39.1 166.0 165.4 2915.05 432.7 0.15 -38.5 166.2 165.7 2916.06 642.1 0.11 -32.0 127.1 126.9 2930.56 579.9 0.07 -33.8 201.0 200.7 2937.6 490.9 0.35 -37.4 178.5 178.1 2948.6 539.6 0.51 -37.2 114.9 114.5 2969.51 537.0 0.52 -36.0 114.8 114.5 2982.6 533.0 0.60 -37.6 114.9 114.4 2993.7 522.7 0.69 -37.2 113.8 113.4 3005.15 483.4 0.66 -35.4 109.2 108.9