Mg/Ca Temperature Calibration for the Benthic Foraminifer Cibicidoides pachyderma ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: Mg/Ca Temperature Calibration for the Benthic Foraminifer Cibicidoides pachyderma LAST UPDATE: 2/2007 (Original receipt by WDC Paleo) CONTRIBUTOR: Tom Marchitto, University of Colorado IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2007-014 SUGGESTED DATA CITATION: Marchitto, T.M.,et al. 2007. Mg/Ca Temperature Calibration for the Benthic Foraminifer Cibicidoides pachyderma. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2007-014. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Marchitto, T.M., S.P. Bryan, W.B. Curry, and D.C. McCorkle. 2007. Mg/Ca temperature calibration for the benthic foraminifer Cibicidoides pachyderma. Paleoceanography, Vol. 22(1), PA1203, doi:10.1029/2006PA001287. ABSTRACT: The recent development of foraminiferal Mg/Ca as a paleotemperature proxy has enabled the extraction of global ice volume and local salinity from the more traditional paleotemperature proxy d18O. The benthic foraminiferal genus Cibicidoides is widely used in paleoceanographic reconstructions because of its epifaunal habitat and cosmopolitan distribution, and it has received early attention in Mg/Ca work. However, existing temperature calibrations for Cibicidoides rely heavily on C. pachyderma core top data from one location, Little Bahamas Bank, where authigenic processes and/or reworking may result in elevated warm water Mg/Ca values. Here we present new C. pachyderma Mg/Ca data from a series of 29 high quality multicore tops collected in the Florida Straits, spanning a temperature range of 5.8 to 18.6°C. In contrast to previous calibrations, we find no evidence for a strongly exponential response to temperature. The data are best explained by a linear relationship, with a sensitivity of 0.12 mmol/mol per °C. GEOGRAPHIC REGION: Florida Straits PERIOD OF RECORD: Holocene/modern FUNDING SOURCES: US National Science Foundation (OCE-0096469, OCE-0550271, OCE-0425522, OCE-0550150) DESCRIPTION: New C. pachyderma Mg/Ca data from a series of 29 high-quality multicore tops collected in the Florida Straits, spanning a temperature range of 5.8–18.6°C. Mg/Ca measured by ICP-MS using "Cd" cleaning procedures. Mg/Ca precision: 0.54% DATA: Table 1. KNR166-2 multicore locations, hydrographic data, C. pachyderma Mg/Ca, and G. ruber radiocarbon ages. Core Latitude Longitude Depth Temperature Salinity DCO32- Mg/Ca Conventional 14C NOSAMS# (°N) (°W) (m) (°C) (psu) (mmol/kg) (umol/mol) age (yr BP) 5 24.4 83.38 447 8.5 35.02 54 2.05 ±0.06 11 24.22 83.3 751 5.8 34.91 55 1.34 355 ±35 OS-399582 13 24.37 83.24 348 9.7 35.17 62 2.39 ±0.08 3040 ±35 OS-460322 16 24.4 83.23 248 10.8 35.32 66 2.34 ±0.09 19 24.42 83.21 173 12.7 35.6 82 2.41 ±0.45 1320 ±50 OS-399672 22 24.41 83.37 398 9 35.08 54 2.56 ±0.10 28 24.28 83.27 648 6.3 34.91 50 1.48 ±0.09 2980 ±40 OS-460372 50 24.41 83.22 198 12.1 35.51 76 2.43 ±0.06 1080 ±45 OS-416462 53 24.38 83.23 302 10 35.21 61 2.28 ±0.12 1800 ±30 OS-399692 55 24.38 83.27 359 9.1 35.1 55 2.29 ±0.06 62 24.33 83.26 547 7 34.91 46 2.19 Fm>1 OS-399711 68 23.61 79.08 431 16.6 36.24 129 3.34 ±0.07 72 23.75 79.43 542 10.8 35.31 70 2.85 ±0.03 76 23.59 79.42 539 11 35.33 67 2.83 ±0.06 79 23.26 79.27 486 12.1 35.5 77 3.25 ±0.14 84 24.37 79.45 638 10.5 35.27 58 2.48 89 24.56 79.24 353 17.8 36.48 149 3.44 2280 ±35 OS-402432 92 24.55 79.26 478 15.7 36.13 124 3.19 94 24.57 79.23 259 18.5 36.57 161 3.41 ±0.09 215 ±35 OS-402442 97 24.56 79.23 303 18.6 36.58 158 3.26 ±0.02 103 24.44 79.48 683 9.3 35.11 53 2.32 ±0.02 110 24.58 79.24 390 17.3 36.39 141 3.31 Fm>1 OS-460392 112 24.64 79.24 404 17.1 36.35 138 2.92 118 24.59 79.27 531 14.5 35.91 104 2.68 Fm>1 OS-399733 121 24.77 79.25 578 11.9 35.48 76 2.58 ±0.13 123 24.76 79.27 632 10.6 35.3 65 2.54 ±0.15 125 24.76 79.29 694 9.4 35.13 57 2.48 Fm>1 OS-399753 134 24.84 79.22 441 17.2 36.37 139 3.04 ±0.14 Fm>1 OS-460432 138 24.83 79.23 484 16.8 36.29 135 2.56 Bottom temperatures were estimated by matching bottle (or estimated) salinities to nearby CTD casts. Italicized salinity and DCO32- data were estimated as described in text. Superscripts on NOSAMS sample numbers indicate source of radiocarbon ages: (1) Lund and Curry (2004); (2) Lund (2005); and (3) Lund and Curry (in press). Fm>1 refers to fraction modern >1, indicating the presence of 14C from nuclear weapons testing. 2. Individual Mg/Ca Core Mg/Ca 5mc 2.09 5mc 2.00 11mc 1.34 13mc 2.33 13mc 2.44 16mc 2.40 16mc 2.27 19mc 2.09 19mc 2.73 22MC-G 2.63 22MC-G 2.49 28mc 1.42 28mc 1.54 50mc 2.39 50mc 2.47 53mc 2.37 53mc 2.20 55mc 2.34 55mc 2.24 62MC-G 2.19 68mc 3.29 68mc 3.39 72MC-G 2.88 72MC-G 2.83 76MC-D 2.87 76MC-D 2.78 79MC-G 3.35 79MC-G 3.15 84mc 2.48 89MC-G 3.44 92MC-E 3.19 94MC-G 3.34 94MC-G 3.47 97MC-G 3.27 97MC-G 3.25 103mc 2.31 103mc 2.34 110mc 3.31 112mc 2.92 118mc 2.68 121mc 2.48 121mc 2.67 123mc 2.44 123mc 2.65 125mc 2.48 134mc 2.94 134mc 3.14 138mc 2.56