Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway
We reconstruct spatial variations in grain size in the sediment routing system of the data-rich Middle Jurassic Brent Group of the northern North Sea, using published stratigraphic, thickness, palaeogeographic, provenance and age constraints combined with representative core and wireline-log data....
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Bibliothèque de l'Université de Genève
2025-01-01
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| Series: | Sedimentologika |
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| Online Access: | https://oap.unige.ch/journals/sdk/article/view/1336 |
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| author | Ikenna C. Okwara Gary J. Hampson Alexander C. Whittaker Gareth G. Roberts |
| author_facet | Ikenna C. Okwara Gary J. Hampson Alexander C. Whittaker Gareth G. Roberts |
| author_sort | Ikenna C. Okwara |
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We reconstruct spatial variations in grain size in the sediment routing system of the data-rich Middle Jurassic Brent Group of the northern North Sea, using published stratigraphic, thickness, palaeogeographic, provenance and age constraints combined with representative core and wireline-log data. Facies associations provide a textural proxy for gravel, sand and mud grain-size fractions, and their distributions define spatio-temporal variations in grain size within four stratigraphic intervals (J22, J24, J26, J32 genetic sequences). Sediment was sourced from the west (Shetland Platform), east (Norwegian Landmass) and south (Mid-North Sea High). The associated sediment routing systems were geographically distinct in the oldest (J22) and youngest (J32) genetic sequences, but combined to feed a large wave-dominated delta (‘Brent Delta’) in genetic sequences J24 and J26. Few of the Brent Group sediment routing systems exhibit the downsystem-fining grain-size trend predicted by sediment mass balance theory. Deviations from this reference trend reflect: (1) sparse sampling of channelised fluvial and fluvio-tidal sand bodies in upsystem locations; (2) preferential trapping of sand in underfilled antecedent and syn-depositional, half-graben depocentres in genetic sequences J22 and J32; and (3) nearshore retention of sand by shoaling waves in wave-dominated shoreface and barrier-strandplain systems. This third type of deviation reveals that spatial facies partitioning due to shallow-marine process regime distorts the simple downsystem-fining reference trend, and supports the interpretation that large volumes of predominantly muddy sediment were bypassed beyond the ‘Brent Delta’ into neighbouring basins. Our analysis demonstrates a practical approach to interpret sediment supply and sediment dispersal in the stratigraphic record.
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| format | Article |
| id | doaj-art-6dd4fe4cc99e4ec2a67b42b435e98d13 |
| institution | Kabale University |
| issn | 2813-415X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Bibliothèque de l'Université de Genève |
| record_format | Article |
| series | Sedimentologika |
| spelling | doaj-art-6dd4fe4cc99e4ec2a67b42b435e98d132025-01-27T02:37:56ZengBibliothèque de l'Université de GenèveSedimentologika2813-415X2025-01-013110.57035/journals/sdk.2025.e31.1336Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and NorwayIkenna C. Okwara0Gary J. Hampson1https://orcid.org/0000-0003-2047-8469Alexander C. Whittaker2Gareth G. Roberts3https://orcid.org/0000-0002-6487-8117Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK and Department of Geology, University of Nigeria, Nsukka, NigeriaDepartment of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UKDepartment of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UKDepartment of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK We reconstruct spatial variations in grain size in the sediment routing system of the data-rich Middle Jurassic Brent Group of the northern North Sea, using published stratigraphic, thickness, palaeogeographic, provenance and age constraints combined with representative core and wireline-log data. Facies associations provide a textural proxy for gravel, sand and mud grain-size fractions, and their distributions define spatio-temporal variations in grain size within four stratigraphic intervals (J22, J24, J26, J32 genetic sequences). Sediment was sourced from the west (Shetland Platform), east (Norwegian Landmass) and south (Mid-North Sea High). The associated sediment routing systems were geographically distinct in the oldest (J22) and youngest (J32) genetic sequences, but combined to feed a large wave-dominated delta (‘Brent Delta’) in genetic sequences J24 and J26. Few of the Brent Group sediment routing systems exhibit the downsystem-fining grain-size trend predicted by sediment mass balance theory. Deviations from this reference trend reflect: (1) sparse sampling of channelised fluvial and fluvio-tidal sand bodies in upsystem locations; (2) preferential trapping of sand in underfilled antecedent and syn-depositional, half-graben depocentres in genetic sequences J22 and J32; and (3) nearshore retention of sand by shoaling waves in wave-dominated shoreface and barrier-strandplain systems. This third type of deviation reveals that spatial facies partitioning due to shallow-marine process regime distorts the simple downsystem-fining reference trend, and supports the interpretation that large volumes of predominantly muddy sediment were bypassed beyond the ‘Brent Delta’ into neighbouring basins. Our analysis demonstrates a practical approach to interpret sediment supply and sediment dispersal in the stratigraphic record. https://oap.unige.ch/journals/sdk/article/view/1336Sediment grain sizeSediment mass-balanceSediment routing systemSource-to-sinkBrent Group |
| spellingShingle | Ikenna C. Okwara Gary J. Hampson Alexander C. Whittaker Gareth G. Roberts Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway Sedimentologika Sediment grain size Sediment mass-balance Sediment routing system Source-to-sink Brent Group |
| title | Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway |
| title_full | Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway |
| title_fullStr | Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway |
| title_full_unstemmed | Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway |
| title_short | Downsystem grain-size trends and mass balance of an ancient wave-influenced sediment routing system: Middle Jurassic Brent Delta, northern North Sea, offshore UK and Norway |
| title_sort | downsystem grain size trends and mass balance of an ancient wave influenced sediment routing system middle jurassic brent delta northern north sea offshore uk and norway |
| topic | Sediment grain size Sediment mass-balance Sediment routing system Source-to-sink Brent Group |
| url | https://oap.unige.ch/journals/sdk/article/view/1336 |
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