Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity
The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK...
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Geological Society of London
2020
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ftdatacite:10.6084/m9.figshare.c.5087313 2023-05-15T14:56:47+02:00 Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity Morton, Nicol Mitta, Vasily V. Underhill, John 2020 https://dx.doi.org/10.6084/m9.figshare.c.5087313 https://geolsoc.figshare.com/collections/Ammonite_occurrences_in_North_Sea_Cores_Implications_for_Jurassic_Arctic-Mediterranean_marine_seaway_connectivity/5087313 unknown Geological Society of London https://dx.doi.org/10.1144/sjg2019-030 Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 CC-BY Geology FOS Earth and related environmental sciences Collection article 2020 ftdatacite https://doi.org/10.6084/m9.figshare.c.5087313 https://doi.org/10.1144/sjg2019-030 2021-11-05T12:55:41Z The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and Sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain “Boreal Bathonian” ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide Zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense Zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and Submediterranean Realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the Submediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi Zones) Amoeboceras in wells 211/21-1 and 9/13b-19, are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A, and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus Zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth. Article in Journal/Newspaper Arctic DataCite Metadata Store (German National Library of Science and Technology) Arctic |
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Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
Geology FOS Earth and related environmental sciences |
spellingShingle |
Geology FOS Earth and related environmental sciences Morton, Nicol Mitta, Vasily V. Underhill, John Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
topic_facet |
Geology FOS Earth and related environmental sciences |
description |
The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and Sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain “Boreal Bathonian” ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide Zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense Zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and Submediterranean Realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the Submediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi Zones) Amoeboceras in wells 211/21-1 and 9/13b-19, are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A, and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus Zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth. |
format |
Article in Journal/Newspaper |
author |
Morton, Nicol Mitta, Vasily V. Underhill, John |
author_facet |
Morton, Nicol Mitta, Vasily V. Underhill, John |
author_sort |
Morton, Nicol |
title |
Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
title_short |
Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
title_full |
Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
title_fullStr |
Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
title_full_unstemmed |
Ammonite occurrences in North Sea Cores: Implications for Jurassic Arctic-Mediterranean marine seaway connectivity |
title_sort |
ammonite occurrences in north sea cores: implications for jurassic arctic-mediterranean marine seaway connectivity |
publisher |
Geological Society of London |
publishDate |
2020 |
url |
https://dx.doi.org/10.6084/m9.figshare.c.5087313 https://geolsoc.figshare.com/collections/Ammonite_occurrences_in_North_Sea_Cores_Implications_for_Jurassic_Arctic-Mediterranean_marine_seaway_connectivity/5087313 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_relation |
https://dx.doi.org/10.1144/sjg2019-030 |
op_rights |
Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode cc-by-4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.c.5087313 https://doi.org/10.1144/sjg2019-030 |
_version_ |
1766328850450481152 |