Early Jurassic North Atlantic sea-surface temperatures from TEX86 palaeothermometry

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doi: 10.1111/sed.12321
Author(s): Robinson, Stuart A.; Ruhl, Micha; Astley, David Lee; Naafs, B. David A.; Farnsworth, Alexander J.; Bown, Paul R.; Jenkyns, Hugh C.; Lunt, Daniel J.; O'Brien, Charlotte; Pancost, Richard D.; Markwick, Paul J.
Author Affiliation(s): Primary:
University of Oxford, Department of Earth Sciences, Oxford, United Kingdom
University of Bristol, United Kingdom
University College London, United Kingdom
Getech, United Kingdom
Volume Title: Mesozoic climates and oceans
Volume Author(s): Robinson, Stuart A., editor; Heimhofer, Ulrich; Hesselbo, Stephen P.; Petrizzo, Maria Rose
Source: Sedimentology, 64(1), p.215-230; Workshop on Mesozoic climates and oceans, Ascona, Switzerland, July 2017, edited by Stuart A. Robinson, Ulrich Heimhofer, Stephen P. Hesselbo and Maria Rose Petrizzo. Publisher: Wiley-Blackwell, Oxford, United Kingdom. ISSN: 0037-0746 CODEN: SEDIAT
Note: In English. 56 refs.; illus., incl. 1 table, sketch maps
Summary: Early Jurassic marine palaeotemperatures have been typically quantified by oxygen-isotope palaeothermometry of benthic and nektonic carbonate and phosphatic macrofossils. However, records of Early Jurassic sea-surface temperatures that can be directly compared with general circulation model simulations of past climates are currently unavailable. The TEX86 sea-surface temperature proxy is based upon the relative abundance of glycerol dialkyl glycerol tetraethers preserved in organic-carbon-bearing sediments. This proxy has been used extensively on Cretaceous and Cenozoic materials and, in one study, on Middle and Upper Jurassic sediments. Here, TEX86 is applied, for the first time, to Lower Jurassic (Sinemurian-Pliensbachian) sediments cored at Deep Sea Drilling Project Site 547 in the North Atlantic. The abundance of glycerol dialkyl glycerol tetraethers in these sediments is very low, despite biomarker and Rock-Eval data suggesting that thermal maturity is, generally, low. Sea floor oxygenation and a high input of reworked terrestrially sourced organic matter may explain the low concentrations. For samples from which it was possible to quantify the relative abundance of glycerol dialkyl glycerol tetraethers, TEX86 values range from 0·78 to 0·88, equating to sea-surface temperatures in excess of >28°C. These temperatures are broadly comparable with new general circulation model simulations of the Sinemurian and Pliensbachian stages and support the general view of a predominantly warm climate. The new proxy data suggest that, under favourable geological conditions, it is possible to extend the record of TEX86-based sea-surface temperatures back into the Early Jurassic. Abstract Copyright (2017), John Wiley & Sons, Ltd.
Year of Publication: 2017
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Atlantic Ocean; Biomarkers; Biostratigraphy; Carbonates; Crystal chemistry; DSDP Site 547; Deep Sea Drilling Project; Geologic thermometry; Glycerol dialkyl glycerol tetraethers; IPOD; Isotope ratios; Isotopes; Jurassic; Leg 79; Lower Jurassic; Marine environment; Mass spectra; Mazagan Plateau; Mesozoic; Microfossils; Models; Nannofossils; North Atlantic; O-18/O-16; Oxygen; Paleo-oceanography; Paleotemperature; Phosphates; Plantae; Pliensbachian; Pyrolysis; Rock-Eval; Sea-surface temperature; Sedimentary rocks; Simulation; Sinemurian; Spectra; Stable isotopes; TEX 86; Thermal maturity
Coordinates: N334650 N334651 W0092058 W0092059
Record ID: 2017029946
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom