Descent toward the icehouse; Eocene sea surface cooling inferred from GDGT distributions

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doi: 10.1002/2014PA002723
Author(s): Inglis, Gordon N.; Farnsworth, Alexander; Lunt, Daniel; Foster, Gavin L.; Hollis, Christopher J.; Pagani, Mark; Jardine, Phillip E.; Pearson, Paul N.; Markwick, Paul; Galsworthy, Amanda M. J.; Raynham, Lauren; Taylor, Kyle W. R.; Pancost, Richard D.
Author Affiliation(s): Primary:
University of Bristol, Organic Geochemistry Unit, Bristol, United Kingdom
Other:
University of Southampton, United Kingdom
GNS Science, New Zealand
Yale University, United States
Open University, United Kingdom
Cardiff University, United Kingdom
Getech UK, United Kingdom
Volume Title: Paleoceanography
Source: Paleoceanography, 30(7), p.1000-1020. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 130 refs.; illus.
Summary: The TEX86 proxy, based on the distribution of marine isoprenoidal glycerol dialkyl glycerol tetraether lipids (GDGTs), is increasingly used to reconstruct sea surface temperature (SST) during the Eocene epoch (56.0-33.9 Ma). Here we compile published TEX86 records, critically reevaluate them in light of new understandings in TEX86 palaeothermometry, and supplement them with new data in order to evaluate long-term temperature trends in the Eocene. We investigate the effect of archaea other than marine Thaumarchaeota upon TEX86 values using the branched-to-isoprenoid tetraether index (BIT), the abundance of GDGT-0 relative to crenarchaeol (%GDGT-0), and the Methane Index (MI). We also introduce a new ratio, %GDGTRS, which may help identify Red Sea-type GDGT distributions in the geological record. Using the offset between TEX86H and TEX86L (ΔH-L) and the ratio between GDGT-2 and GDGT-3 ([2]/[3]), we evaluate different TEX86 calibrations and present the first integrated SST compilation for the Eocene (55 to 34 Ma). Although the available data are still sparse some geographic trends can now be resolved. In the high latitudes (>55°), there was substantial cooling during the Eocene (∼6°C). Our compiled record also indicates tropical cooling of ∼2.5°C during the same interval. Using an ensemble of climate model simulations that span the Eocene, our results indicate that only a small percentage (∼10%) of the reconstructed temperature change can be ascribed to ocean gateway reorganization or paleogeographic change. Collectively, this indicates that atmospheric carbon dioxide (pCO2) was the likely driver of surface water cooling during the descent toward the icehouse. Abstract Copyright (2015), . The Authors.
Year of Publication: 2015
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Arctic Coring EXpedition; Arctic Ocean; Atlantic Ocean; Australasia; Campbell Plateau; Caribbean Sea; Ceara Rise; Cenozoic; Climate change; DSDP Site 277; DSDP Site 511; Deep Sea Drilling Project; East Africa; East Pacific; Eocene; Equatorial Atlantic; Equatorial Pacific; Expedition 318; IODP Site U1356; IPOD; Icehouse effect; Integrated Ocean Drilling Program; Leg 101; Leg 130; Leg 151; Leg 154; Leg 165; Leg 189; Leg 199; Leg 29; Leg 71; Lipids; Little Bahama Bank; Marine environment; New Zealand; North Atlantic; North Pacific; Northeast Pacific; Northwest Pacific; Norwegian Sea; ODP Site 1172; ODP Site 1218; ODP Site 628; ODP Site 803; ODP Site 913; ODP Site 925; ODP Site 929; ODP Site 998; Ocean Drilling Program; Ontong Java Plateau; Organic compounds; Pacific Ocean; Paleoclimatology; Paleoenvironment; Paleogene; Paleotemperature; Sea-surface temperature; South Atlantic; South Pacific; Southern Ocean; Southwest Pacific; Statistical analysis; Tanzania; Tasman Sea; Tertiary; West Pacific
Coordinates: N273139 N273139 W0781857 W0781857
N055834 N055834 W0434423 W0434423
S521326 S521325 E1661129 E1661128
S510017 S510017 W0465818 W0465818
Record ID: 2015099150
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom