Models of organic enrichment in epicontinental basins: Applications of a large organic geochemical dataset from the Cretaceous Western Interior Seaway
Models of organic enrichment in epicontinental basins: Applications of a large organic geochemical dataset from the Cretaceous Western Interior Seaway
This study provides a new data synthesis and interpretation of organic enrichment models within the Cretaceous Western Interior Seaway (WIS), an archetypal restricted epicontinental seaway. This study draws from 323 unique published resources (e.g., government datasets, journal articles, theses, reports) containing organic geochemical data (Rock-Eval and lipid biomarkers) to construct a database of over 18,000 samples at 994 locations across the WIS. Through rigorous standardisation techniques, quality control checks and the inclusion of complementary culture data, maps of paleogeography, thermal maturity, Total Organic Carbon and Hydrogen Index were created for nine key sea-level cycles across the Cretaceous. In addition, we provide an analysis of more specific paleoenvironmental proxies based on lipid biomarkers. Collated data show that the WIS is an organic-rich basin during all sea-level cycles studied herein, and organic enrichment generally increases both during high sea-levels and at distal locations away from the influence of higher clastic inputs. A tipping point is identified between the Mowry and Graneros sea-level cycles whereby water depth becomes sufficient to allow for prolonged stratification, and Gammacerane Index suggests heightened stratification across the WIS through the Graneros and Greenhorn cycles. Organic enrichment correlates with abundance of C28 steranes, a proxy for prasinophytes and indicator of anoxic waters, further suggesting that anoxia drives organic enrichment in the WIS. The reported oceanographic overturning and oxygenation events within the high sea-levels of the Greenhorn and Niobrara cycles do not appear to have resulted in a significant decrease of overall organic matter preservation.
Organic geochemistry, Organic matter, Paleoceanography, Rock-Eval
Robinson, Libby J.
67deebbb-0394-4d4a-9aba-4f2b0f0982c3
Whiteside, Jessica
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
June 2022
Robinson, Libby J.
67deebbb-0394-4d4a-9aba-4f2b0f0982c3
Whiteside, Jessica
5d9ad7aa-eba3-4ad9-9f6f-81be71b6829b
Robinson, Libby J. and Whiteside, Jessica
(2022)
Models of organic enrichment in epicontinental basins: Applications of a large organic geochemical dataset from the Cretaceous Western Interior Seaway.
Cretaceous Research, 105160 (0195-6671), [105160].
(doi:10.1016/j.cretres.2022.105160).
Abstract
This study provides a new data synthesis and interpretation of organic enrichment models within the Cretaceous Western Interior Seaway (WIS), an archetypal restricted epicontinental seaway. This study draws from 323 unique published resources (e.g., government datasets, journal articles, theses, reports) containing organic geochemical data (Rock-Eval and lipid biomarkers) to construct a database of over 18,000 samples at 994 locations across the WIS. Through rigorous standardisation techniques, quality control checks and the inclusion of complementary culture data, maps of paleogeography, thermal maturity, Total Organic Carbon and Hydrogen Index were created for nine key sea-level cycles across the Cretaceous. In addition, we provide an analysis of more specific paleoenvironmental proxies based on lipid biomarkers. Collated data show that the WIS is an organic-rich basin during all sea-level cycles studied herein, and organic enrichment generally increases both during high sea-levels and at distal locations away from the influence of higher clastic inputs. A tipping point is identified between the Mowry and Graneros sea-level cycles whereby water depth becomes sufficient to allow for prolonged stratification, and Gammacerane Index suggests heightened stratification across the WIS through the Graneros and Greenhorn cycles. Organic enrichment correlates with abundance of C28 steranes, a proxy for prasinophytes and indicator of anoxic waters, further suggesting that anoxia drives organic enrichment in the WIS. The reported oceanographic overturning and oxygenation events within the high sea-levels of the Greenhorn and Niobrara cycles do not appear to have resulted in a significant decrease of overall organic matter preservation.
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Accepted/In Press date: 19 January 2022
e-pub ahead of print date: 31 January 2022
Published date: June 2022
Additional Information:
Funding Information:
LJR would like to thank Rachel Round and Mike Simmons (Halliburton) for their helpful discussions and suggestions. This work was supported by the Natural Environmental Research Council (grant number NE/L002531/1 ) and AAPG Foundation Grant-in-Aid (Marta S. Weeks Named Grant). We would like to thank Judith Parrish, Mark Leckie and James Eldrett for thoughtful comments that improved the manuscript during the review process.
Funding Information:
LJR would like to thank Rachel Round and Mike Simmons (Halliburton) for their helpful discussions and suggestions. This work was supported by the Natural Environmental Research Council (grant number NE/L002531/1) and AAPG Foundation Grant-in-Aid (Marta S. Weeks Named Grant). We would like to thank Judith Parrish, Mark Leckie and James Eldrett for thoughtful comments that improved the manuscript during the review process.
Publisher Copyright:
© 2022 Elsevier Ltd
Keywords:
Organic geochemistry, Organic matter, Paleoceanography, Rock-Eval
Identifiers
Local EPrints ID: 455162
URI: http://eprints.soton.ac.uk/id/eprint/455162
ISSN: 0195-6671
PURE UUID: 6b9ca99f-8129-4420-9818-3ad37e808098
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Date deposited: 10 Mar 2022 20:16
Last modified: 16 Mar 2024 16:06
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Author:
Libby J. Robinson
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