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Foster, Gavin L; Lear, Caroline H; Rae, James William B (2012): (Table S1) Boron isotope and trace element data and reconstructed carbonate system parameters, ODP Holes 122-761B and 154-926A. PANGAEA, https://doi.org/10.1594/PANGAEA.815855, Supplement to: Foster, GL et al. (2012): The evolution of pCO2, ice volume and climate during the middle Miocene. Earth and Planetary Science Letters, 341-344, 243-254, https://doi.org/10.1016/j.epsl.2012.06.007

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Abstract:
The middle Miocene Climatic Optimum (17-15 Ma; MCO) is a period of global warmth and relatively high CO2 and is thought to be associated with a significant retreat of the Antarctic Ice Sheet (AIS). We present here a new planktic foraminiferal d11B record from 16.6 to 11.8 Ma from two deep ocean sites currently in equilibrium with the atmosphere with respect to CO2. These new data demonstrate that the evolution of global climate during the middle Miocene (as reflected by changes in the cyrosphere) was well correlated to variations in the concentration of atmospheric CO2. What is more, within our sampling resolution (~1 sample per 300 kyr) there is no evidence of hysteresis in the response of ice volume to CO2 forcing during the middle Miocene, contrary to what is understood about the Antarctic Ice Sheet from ice sheet modelling studies. In agreement with previous data, we show that absolute levels of CO2 during the MCO were relatively modest (350-400 ppm) and levels either side of the MCO are similar or lower than the pre-industrial (200-260 ppm). These new data imply the presence of either a very dynamic AIS at relatively low CO2 during the middle Miocene or the advance and retreat of significant northern hemisphere ice. Recent drilling on the Antarctic margin and shore based studies indicate significant retreat and advance beyond the modern limits of the AIS did occur during the middle Miocene, but the complete loss of the AIS was unlikely. Consequently, it seems that ice volume and climate variations during the middle Miocene probably involved a more dynamic AIS than the modern but also some component of land-based ice in the northern hemisphere.
Further details:
Horita, Juske; Zimmermann, Heide; Holland, Heinrich D (2002): Chemical evolution of seawater during the Phanerozoic. Geochimica et Cosmochimica Acta, 66(21), 3733-3756, https://doi.org/10.1016/S0016-7037(01)00884-5
Project(s):
Coverage:
Median Latitude: -6.508950 * Median Longitude: 36.313450 * South-bound Latitude: -16.737000 * West-bound Longitude: -42.908100 * North-bound Latitude: 3.719100 * East-bound Longitude: 115.535000
Date/Time Start: 1988-07-19T10:00:00 * Date/Time End: 1994-02-21T10:30:00
Minimum DEPTH, sediment/rock: 37.3 m * Maximum DEPTH, sediment/rock: 290.8 m
Event(s):
122-761B * Latitude: -16.737000 * Longitude: 115.535000 * Date/Time Start: 1988-07-19T10:00:00 * Date/Time End: 1988-07-21T09:00:00 * Elevation: -2179.0 m * Penetration: 286.7 m * Recovery: 199.08 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 286.7 m cored; 0 m drilled; 69.4 % recovery
154-926A * Latitude: 3.719100 * Longitude: -42.908100 * Date/Time Start: 1994-02-19T11:30:00 * Date/Time End: 1994-02-21T10:30:00 * Elevation: -3610.0 m * Penetration: 327 m * Recovery: 334.92 m * Location: North Atlantic Ocean * Campaign: Leg154 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 35 cores; 327 m cored; 0 m drilled; 102.4 % recovery
Comment:
Sediment depth is given in mcd. Carbonate system parameters calculated using d11B(seawater) = 37.82 per mil and ALK(surface) = 1292 mmol/kg and ALK(deep) = 1392 mmol/kg. All carbonate system calculations were carried out accounting for the effect of changing [Ca] and [Mg] on K1, K2 and Ksp.
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Event labelEvent
2Sample code/labelSample labelFoster, Gavin LODP sample designation
3DEPTH, sediment/rockDepthmGeocode
4AGEAgeka BPGeocode
5SpeciesSpeciesFoster, Gavin L
6Globigerinoides sacculifer, Magnesium/Calcium ratioG. sacculifer Mg/Cammol/molFoster, Gavin LICP-MS, Thermo Fisher Scientific, Element 2
7Cibicidoides wuellerstorfi, Magnesium/Calcium ratioC. wuellerstorfi Mg/Cammol/molFoster, Gavin LICP-MS, Thermo Fisher Scientific, Element 2
8Cibicidoides mundulus, Magnesium/Calcium ratioC. mundulus Mg/Cammol/molFoster, Gavin LICP-MS, Thermo Fisher Scientific, Element 2
9delta 11Bd11Bper mil SRMFoster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUN#1
10Standard errorStd e±Foster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUNd11B 2 se, #1
11BoronBmg/kgFoster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUN#1
12delta 11Bd11Bper mil SRMFoster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUN#2
13Standard errorStd e±Foster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUNd11B 2 se, #2
14BoronBmg/kgFoster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUN#2
15delta 11Bd11Bper mil SRMFoster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUNaverage of two repeat measurements
16delta 11B, standard deviationd11B std dev±Foster, Gavin LMC-ICP-MS, Thermo Fisher Scientific NEPTUN2 sd of average of two repeat measurements
17Temperature, calculatedT cal°CFoster, Gavin LCalculatedfrom Mg/Ca using equations and the Mg/Ca ratio of seawater from Horita et al. (2002)
18pHpHFoster, Gavin LCalculatedtotal scale
19ErrorErrorFoster, Gavin LCalculateduncertainty due to measurement uncertainty on d11B determination
20Carbonate ion[CO3]2-µmol/kgFoster, Gavin LCalculated
21Carbonate ion, standard deviation[CO3]2- std dev±Foster, Gavin LCalculatedsummed uncertainty due to ± 200 mmol/kg total alkalinity and ± uncertainty in d11B, for pCO2 this also includes an uncertainty due to temperature
22Carbon dioxide, partial pressurepCO2ppmvFoster, Gavin LCalculated
23Carbon dioxide, partial pressure, standard deviationpCO2 std dev±Foster, Gavin LCalculated+ 2 sigma
24Carbon dioxide, partial pressure, standard deviationpCO2 std dev±Foster, Gavin LCalculated- 2 sigma
Size:
342 data points

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