Williscroft, K, Grasby, SE, Beauchamp, B et al. (5 more authors) (2017) Extensive Lower Cretaceous (Albian) methane seepage on Ellef Ringnes Island, Canadian High Arctic. Geological Society of America Bulletin, 129 (7-8). pp. 788-805. ISSN 0016-7606
Abstract
During field mapping of Ellef Ringnes Island, Canadian Arctic Archipelago, 139 isolated Lower Cretaceous methane seep deposits were found from 75 field sites. Stable isotopes of the carbonates have values of δ13C= -47‰ to -35‰ and δ18O= -4.0‰ to +0.7‰. Isoprenoids in organics from one of the seeps are significantly depleted in 13C, with the most negative δ13C of = -118 ‰ and -113 ‰ for PMI and phytane/crocetane, respectively. These values indicate an origin through methane oxidation, consistent with biomarkers that are characteristic for anaerobic methanotrophic archaea within the seep deposits, accompanied by terminally-branched fatty acids sourced by sulphate-reducing bacteria, showing similar 13C values (-92‰). The seep deposits contain a moderate diversity macrofaunal assemblage containing ammonites, bivalves, gastropods, scaphopods, ‘vestimentiferan’ worm tubes and brachiopods. The assemblage is dominated numerically by species that probably had chemosymbionts. The seep deposits formed in the subsurface with strong redox zones, in an otherwise normal marine setting, characterised by oxic waters at high paleolatitudes. While geographically widespread, over an area of ~10,000 km2, seep deposits on Ellef Ringnes Island occur in a narrow stratigraphic horizon, suggesting a large release of biogenic methane occurred over a brief period of time. This gas release was coincident with a transition from a cold to warm climate during the latest Early Albian, and we hypothetize that this may relate to gas hydrate release.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Geological Society of America. This is an author produced version of a paper published in Geological Society of America Bulletin. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 10 Feb 2017 15:55 |
Last Modified: | 07 Apr 2018 00:38 |
Status: | Published |
Publisher: | Geological Society of America |
Identification Number: | 10.1130/B31601.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:112175 |