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The southern margin of the Rockall Plateau: stratigraphy, Tertiary volcanism and plate tectonic evolution

The southern margin of the Rockall Plateau: stratigraphy, Tertiary volcanism and plate tectonic evolution
The southern margin of the Rockall Plateau: stratigraphy, Tertiary volcanism and plate tectonic evolution
The geological evolution of the southwest Rockall Plateau in the area of Edoras Bank has been clarified using seismic reflection, gravity and magnetic data. Four principal reflectors are observed within the Tertiary sedimentary sequence: I, Late Miocene; 11, latest Early Miocene; 111, Late Eocene; IV, earliest Eocene. A period of pronounced sediment drift accumulation marks the interval 1-11. Reflector 111, the top of a sediment wedge prograding southward from Edoras Bank, marks a change from terrigenous to pelagic sedimentation that is probably related to subsidence of the Rockall Plateau following the separation of Greenland from Eurasia in the earliest Eocene. Reflector IV marks the top of a wedge-shaped seismically transparent layer that also thins southward away from Edoras Bank. On the basis of its seismic attributes and magnetic signature, this layer is interpreted as a volcanic sheet, formed as part of the North Atlantic Tertiary Volcanic Province during rifting of Greenland from Eurasia. The recognition of voluminous volcanic rocks south of Edoras Bank extends the known area of the Tertiary volcanic province several hundred kilometres to the south. Gravity anomaly modelling and continental reconstructions suggest that the region south of Edoras Bank is underlain by thinned continental crust. A four stage geological evolution for this region is indicated. (i) Initial rifting associated with the separation of Labrador from Greenland in the late Cretaceous is characterized by enhanced crustal thinning and subsidence in the region of a rift triple junction. (ii) Passive subsidence and accumulation of late Cretaceous and earliest Tertiary sediments followed the initiation of seafloor spreading in the Labrador Sea. (iii) Blanketing of the area by Palaeocene volcanic rocks masked pre-existing magnetic lineations, providing an explanation for some of the problems in earlier interpretations based mainly on magnetic data. (iv) Post-volcanic sedimentation, continuing to the present day.
0016-7649
601-612
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45

Bull, Jonathan M. and Masson, Douglas G. (1996) The southern margin of the Rockall Plateau: stratigraphy, Tertiary volcanism and plate tectonic evolution. Journal of the Geological Society, 153 (4), 601-612. (doi:10.1144/gsjgs.153.4.0601).

Record type: Article

Abstract

The geological evolution of the southwest Rockall Plateau in the area of Edoras Bank has been clarified using seismic reflection, gravity and magnetic data. Four principal reflectors are observed within the Tertiary sedimentary sequence: I, Late Miocene; 11, latest Early Miocene; 111, Late Eocene; IV, earliest Eocene. A period of pronounced sediment drift accumulation marks the interval 1-11. Reflector 111, the top of a sediment wedge prograding southward from Edoras Bank, marks a change from terrigenous to pelagic sedimentation that is probably related to subsidence of the Rockall Plateau following the separation of Greenland from Eurasia in the earliest Eocene. Reflector IV marks the top of a wedge-shaped seismically transparent layer that also thins southward away from Edoras Bank. On the basis of its seismic attributes and magnetic signature, this layer is interpreted as a volcanic sheet, formed as part of the North Atlantic Tertiary Volcanic Province during rifting of Greenland from Eurasia. The recognition of voluminous volcanic rocks south of Edoras Bank extends the known area of the Tertiary volcanic province several hundred kilometres to the south. Gravity anomaly modelling and continental reconstructions suggest that the region south of Edoras Bank is underlain by thinned continental crust. A four stage geological evolution for this region is indicated. (i) Initial rifting associated with the separation of Labrador from Greenland in the late Cretaceous is characterized by enhanced crustal thinning and subsidence in the region of a rift triple junction. (ii) Passive subsidence and accumulation of late Cretaceous and earliest Tertiary sediments followed the initiation of seafloor spreading in the Labrador Sea. (iii) Blanketing of the area by Palaeocene volcanic rocks masked pre-existing magnetic lineations, providing an explanation for some of the problems in earlier interpretations based mainly on magnetic data. (iv) Post-volcanic sedimentation, continuing to the present day.

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More information

Published date: 1996
Organisations: Geology & Geophysics, Marine Geoscience

Identifiers

Local EPrints ID: 363783
URI: https://eprints.soton.ac.uk/id/eprint/363783
ISSN: 0016-7649
PURE UUID: ed5064ae-da80-432f-aca8-3ed2b1892d4e

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Date deposited: 03 Apr 2014 09:43
Last modified: 16 Jul 2019 21:08

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