Drury, Anna Joy; John, Cédric M; Shevenell, Amelia E (2016): Orbital-scale climate variability of high-resolution records spanning 8.0-3.5 Ma from IODP Site 321-U1338 and ODP Site 982. PANGAEA, https://doi.org/10.1594/PANGAEA.856679, Supplement to: Drury, AJ et al. (2016): Evaluating climatic response to external radiative forcing during the late Miocene to early Pliocene: New perspectives from eastern equatorial Pacific (IODP U1338) and North Atlantic (ODP 982) locations. Paleoceanography, 31(1), 167-184, https://doi.org/10.1002/2015PA002881
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Orbital-scale climate variability during the latest Miocene-early Pliocene is poorly understood due to a lack of high-resolution records spanning 8.0-3.5 Ma, which resolve all orbital cycles. Assessing this variability improves understanding of how Earth's system sensitivity to insolation evolves and provides insight into the factors driving the Messinian Salinity Crisis (MSC) and the Late Miocene Carbon Isotope Shift (LMCIS). New high-resolution benthic foraminiferal Cibicidoides mundulus d18O and d13C records from equatorial Pacific International Ocean Drilling Program Site U1338 are correlated to North Atlantic Ocean Drilling Program Site 982 to obtain a global perspective. Four long-term benthic d18O variations are identified: the Tortonian-Messinian, Miocene-Pliocene, and Early-Pliocene Oxygen Isotope Lows (8-7, 5.9-4.9, and 4.8-3.5 Ma) and the Messinian Oxygen Isotope High (MOH; 7-5.9 Ma). Obliquity-paced variability dominates throughout, except during the MOH. Eleven new orbital-scale isotopic stages are identified between 7.4 and 7.1 Ma. Cryosphere and carbon cycle sensitivities, estimated from d18O and d13C variability, suggest a weak cryosphere-carbon cycle coupling. The MSC termination coincided with moderate cryosphere sensitivity and reduced global ice sheets. The LMCIS coincided with reduced carbon cycle sensitivity, suggesting a driving force independent of insolation changes. The response of the cryosphere and carbon cycle to obliquity forcing is established, defined as Earth System Response (ESR). Observations reveal that two late Miocene-early Pliocene climate states existed. The first is a prevailing dynamic state with moderate ESR and obliquity-driven Antarctic ice variations, associated with reduced global ice volumes. The second is a stable state, which occurred during the MOH, with reduced ESR and lower obliquity-driven variability, associated with expanded global ice volumes.
Latitude: 2.507800 * Longitude: -117.969910
Datasets listed in this publication series
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table 1) New marine isotope stage identification: 7.1-7.4 Ma and long-term oxygen and carbon isotope trends of IODP Site 321-U1338 and ODP Site 162-982. https://doi.org/10.1594/PANGAEA.856725
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table S2) First order shipboard age model of IODP Site 321-U1338. https://doi.org/10.1594/PANGAEA.856730
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table S3) Oxygen and carbon isotope ratios of the epifaunal benthic foraminifera Cibicidoides mundulus of IODP Site 321-U1338. https://doi.org/10.1594/PANGAEA.856675
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table S5) Sedimentation rates of IODP Site 321-U1338. https://doi.org/10.1594/PANGAEA.856687
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table S6) Second generation match age mode of IODP Site 321-U1338. https://doi.org/10.1594/PANGAEA.856685
- Drury, AJ; John, CM; Shevenell, AE (2016): (Table S7) Resampled benthic foraminifera δ¹⁸O records of IODP Site 321-U1338. https://doi.org/10.1594/PANGAEA.856673