Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard
The organic-rich shales of the Middle Triassic Botneheia Formation in Svalbard and its correlative units offshore are considered important source rock intervals for oil and gas generation in the Norwegian Barents Shelf region. Detailed investigation of these intervals is essential to better understa...
Published in: | Marine and Petroleum Geology |
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Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2021
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Subjects: | |
Online Access: | http://hdl.handle.net/10852/87938 http://urn.nb.no/URN:NBN:no-90580 https://doi.org/10.1016/j.marpetgeo.2021.105168 |
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ftoslouniv:oai:www.duo.uio.no:10852/87938 |
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Open Polar |
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Universitet i Oslo: Digitale utgivelser ved UiO (DUO) |
op_collection_id |
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language |
English |
description |
The organic-rich shales of the Middle Triassic Botneheia Formation in Svalbard and its correlative units offshore are considered important source rock intervals for oil and gas generation in the Norwegian Barents Shelf region. Detailed investigation of these intervals is essential to better understand the intra source rock variations and thus to improve exploration models. As source rocks are rarely cored during exploration campaigns, outcrop studies of analogue source rocks onshore Svalbard are of great importance for gaining a comprehensive understanding of the Triassic petroleum system offshore. This integrated sedimentological and geochemical study of the Botneheia Formation investigates the intricate relationship between mudstone facies, total sulfur, total organic/inorganic carbon, and the absolute and relative abundance of bulk bitumen content. Both the Muen Member (Anisian) and the overlying Blanknuten Member (mostly Ladinian) of the Botneheia Formation were densely sampled and analyzed from three outcrop localities on Edgeøya, eastern Svalbard. The results show that total sulfur, total organic carbon, bitumen richness, and relative and absolute aromatic hydrocarbon content increase from bioturbated, gray-colored shales in the lower to middle Muen Member upwards into non-bioturbated, phosphogenic black shales in the middle part of the Blanknuten Member. From here, organic carbon and bulk bitumen richness subsequently decrease upwards in concert with the occurrence of bioturbated, calcareous mudstones and impure limestones towards the top of the Blanknuten Member. Optical vitrinite reflectance variations do not suggest significant maturity variations with depth in the sample profiles, highlighting that the total organic carbon and bulk bitumen content are dominantly coupled with the developing source facies. These facies and chemostratigraphic trends mirror the implied marine vs. terrigenous organic matter sedimentation and benthic preservation potential, which were at a maximum in the middle Blanknuten Member. These processes appear to be closely related to the supply of nutritious upwelled waters that are further linked with an evolving pan-Arctic 2nd order Middle Triassic transgressive–regressive sequence. Facies and multivariate analyses of the geochemical data show that the lower to middle Muen Member are comparable to the pro-delta mudstones of the younger Tschermakfjellet Formation (Carnian), and that both units are clearly distinct from the increased source rock potential and richness in the upper part of the Muen Member and the entire Blanknuten Member. This provides evidence of genetically different paleo-depositional environments and source rock properties that are confined to the lower and upper parts of the Middle Triassic Botneheia Formation, and may have wide applications for Triassic source rock assessment in the offshore Norwegian Barents Sea |
format |
Article in Journal/Newspaper |
author |
Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard |
spellingShingle |
Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
author_facet |
Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard |
author_sort |
Wesenlund, Fredrik |
title |
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
title_short |
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
title_full |
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
title_fullStr |
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
title_full_unstemmed |
Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard |
title_sort |
linking facies variations, organic carbon richness and bulk bitumen content – a case study of the organic-rich middle triassic shales from eastern svalbard |
publishDate |
2021 |
url |
http://hdl.handle.net/10852/87938 http://urn.nb.no/URN:NBN:no-90580 https://doi.org/10.1016/j.marpetgeo.2021.105168 |
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ENVELOPE(21.263,21.263,77.987,77.987) ENVELOPE(16.500,16.500,78.300,78.300) ENVELOPE(22.500,22.500,77.750,77.750) ENVELOPE(21.479,21.479,77.810,77.810) ENVELOPE(15.290,15.290,78.514,78.514) |
geographic |
Arctic Barents Sea Blanknuten Botneheia Edgeøya Muen Svalbard Tschermakfjellet |
geographic_facet |
Arctic Barents Sea Blanknuten Botneheia Edgeøya Muen Svalbard Tschermakfjellet |
genre |
Arctic Barents Sea Edgeøya Svalbard |
genre_facet |
Arctic Barents Sea Edgeøya Svalbard |
op_source |
0264-8172 |
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NFR/228107 http://urn.nb.no/URN:NBN:no-90580 Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard . Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard. Marine and Petroleum Geology. 2021, 132 http://hdl.handle.net/10852/87938 1931035 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Marine and Petroleum Geology&rft.volume=132&rft.spage=&rft.date=2021 Marine and Petroleum Geology 132 https://doi.org/10.1016/j.marpetgeo.2021.105168 URN:NBN:no-90580 Fulltext https://www.duo.uio.no/bitstream/handle/10852/87938/1/1-s2.0-S0264817221002713-main.pdf |
op_rights |
Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/j.marpetgeo.2021.105168 |
container_title |
Marine and Petroleum Geology |
container_volume |
132 |
container_start_page |
105168 |
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1766349807697264640 |
spelling |
ftoslouniv:oai:www.duo.uio.no:10852/87938 2023-05-15T15:19:36+02:00 Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard 2021-09-03T09:17:42Z http://hdl.handle.net/10852/87938 http://urn.nb.no/URN:NBN:no-90580 https://doi.org/10.1016/j.marpetgeo.2021.105168 EN eng NFR/228107 http://urn.nb.no/URN:NBN:no-90580 Wesenlund, Fredrik Grundvåg, Sten-Andreas Engelschiøn, Victoria Sjøholt Thießen, Olaf Pedersen, Jon Halvard . Linking facies variations, organic carbon richness and bulk bitumen content – A case study of the organic-rich Middle Triassic shales from eastern Svalbard. Marine and Petroleum Geology. 2021, 132 http://hdl.handle.net/10852/87938 1931035 info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Marine and Petroleum Geology&rft.volume=132&rft.spage=&rft.date=2021 Marine and Petroleum Geology 132 https://doi.org/10.1016/j.marpetgeo.2021.105168 URN:NBN:no-90580 Fulltext https://www.duo.uio.no/bitstream/handle/10852/87938/1/1-s2.0-S0264817221002713-main.pdf Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ CC-BY 0264-8172 Journal article Tidsskriftartikkel Peer reviewed PublishedVersion 2021 ftoslouniv https://doi.org/10.1016/j.marpetgeo.2021.105168 2021-09-15T22:31:51Z The organic-rich shales of the Middle Triassic Botneheia Formation in Svalbard and its correlative units offshore are considered important source rock intervals for oil and gas generation in the Norwegian Barents Shelf region. Detailed investigation of these intervals is essential to better understand the intra source rock variations and thus to improve exploration models. As source rocks are rarely cored during exploration campaigns, outcrop studies of analogue source rocks onshore Svalbard are of great importance for gaining a comprehensive understanding of the Triassic petroleum system offshore. This integrated sedimentological and geochemical study of the Botneheia Formation investigates the intricate relationship between mudstone facies, total sulfur, total organic/inorganic carbon, and the absolute and relative abundance of bulk bitumen content. Both the Muen Member (Anisian) and the overlying Blanknuten Member (mostly Ladinian) of the Botneheia Formation were densely sampled and analyzed from three outcrop localities on Edgeøya, eastern Svalbard. The results show that total sulfur, total organic carbon, bitumen richness, and relative and absolute aromatic hydrocarbon content increase from bioturbated, gray-colored shales in the lower to middle Muen Member upwards into non-bioturbated, phosphogenic black shales in the middle part of the Blanknuten Member. From here, organic carbon and bulk bitumen richness subsequently decrease upwards in concert with the occurrence of bioturbated, calcareous mudstones and impure limestones towards the top of the Blanknuten Member. Optical vitrinite reflectance variations do not suggest significant maturity variations with depth in the sample profiles, highlighting that the total organic carbon and bulk bitumen content are dominantly coupled with the developing source facies. These facies and chemostratigraphic trends mirror the implied marine vs. terrigenous organic matter sedimentation and benthic preservation potential, which were at a maximum in the middle Blanknuten Member. These processes appear to be closely related to the supply of nutritious upwelled waters that are further linked with an evolving pan-Arctic 2nd order Middle Triassic transgressive–regressive sequence. Facies and multivariate analyses of the geochemical data show that the lower to middle Muen Member are comparable to the pro-delta mudstones of the younger Tschermakfjellet Formation (Carnian), and that both units are clearly distinct from the increased source rock potential and richness in the upper part of the Muen Member and the entire Blanknuten Member. This provides evidence of genetically different paleo-depositional environments and source rock properties that are confined to the lower and upper parts of the Middle Triassic Botneheia Formation, and may have wide applications for Triassic source rock assessment in the offshore Norwegian Barents Sea Article in Journal/Newspaper Arctic Barents Sea Edgeøya Svalbard Universitet i Oslo: Digitale utgivelser ved UiO (DUO) Arctic Barents Sea Blanknuten ENVELOPE(21.263,21.263,77.987,77.987) Botneheia ENVELOPE(16.500,16.500,78.300,78.300) Edgeøya ENVELOPE(22.500,22.500,77.750,77.750) Muen ENVELOPE(21.479,21.479,77.810,77.810) Svalbard Tschermakfjellet ENVELOPE(15.290,15.290,78.514,78.514) Marine and Petroleum Geology 132 105168 |