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Geochemistry and petrology of palaeocene coals from Spitzbergen — Part 2: Maturity variations and implications for local and regional burial models

Marshall, Chris; Uguna, Jacob.; Large, David J.; Meredith, William; Jochmann, Malte; Friis, Bjarki; Vane, Chris; Spiro, Baruch F.; Snape, Colin E.; Orheim, Alv

Authors

Chris Marshall

Jacob. Uguna

DAVID LARGE David.Large@nottingham.ac.uk
Abbott Professor of Geoscience

Malte Jochmann

Bjarki Friis

Chris Vane

Baruch F. Spiro

COLIN SNAPE COLIN.SNAPE@NOTTINGHAM.AC.UK
Professor of Chemical Technology & Chemical Eng

Alv Orheim



Abstract

The Central Tertiary Basin is an uplifted part of the North Barents Shelf and should be an ideal location to understand the thermal history, maximum burial depth and overburden thickness in this petroleum-rich area. Efforts to quantify the thermal history of the region have been hampered by reports of hyper-thermal conditions, maturity gaps and maturity inversions in the Tertiary vitrinite reflectance (Ro) record. This has been attributed to thermal insulation effects, vitrinite reflectance due to bitumen impregnation and later Tertiary volcanism. Through the use of Ro, organic maturity parameters, 13C NMR and Rock–Eval pyrolysis, this study aims to explain the unusual maturity effects observed and the implications for burial models. Within single seams, Ro % ranges from 0.5 to 0.78 with increasingly bimodal distribution up-seam. Analysis of coal aromaticity and the results of Rock–Eval analysis confirm that maturity gaps and inversions only occur where the vitrinite reflectance has been suppressed by high bitumen content (300–400 mg/g coal). Samples with the lowest hydrogen index values (< 250 mg HC / TOC) provide the most accurate estimates of the vitrinite reflectance. Results indicate maximum burial temperatures of 120 °C in the basin centre and 100 °C at the basin margins with a hyper-thermal gradient of approximately 50 °C/km. This gradient implies a total overburden of 2 km of which 1 km has been lost. Maximum burial depth and total erosional sediment load to the Barents Shelf are therefore at the lower end of current estimates.

Journal Article Type Article
Publication Date 2015-04
Journal International Journal of Coal Geology
Print ISSN 0166-5162
Electronic ISSN 1872-7840
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 143
Pages 1-10
APA6 Citation Marshall, C., Uguna, J., Large, D. J., Meredith, W., Jochmann, M., Friis, B., …Orheim, A. (2015). Geochemistry and petrology of palaeocene coals from Spitzbergen — Part 2: Maturity variations and implications for local and regional burial models. International Journal of Coal Geology, 143, 1-10. https://doi.org/10.1016/j.coal.2015.03.013
DOI https://doi.org/10.1016/j.coal.2015.03.013
Keywords Vitrinite reflectance; Oil prone coal; Maturity; Barents shelf; Spitsbergen
Publisher URL http://www.sciencedirect.com/science/article/pii/S0166516215000452
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0
Additional Information This article is maintained by: Elsevier; Article Title: Geochemistry and petrology of palaeocene coals from Spitzbergen — Part 2: Maturity variations and implications for local and regional burial models; Journal Title: International Journal of Coal Geology; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.coal.2015.03.013; Content Type: article; Copyright: Copyright © 2015 Elsevier B.V. All rights reserved.

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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