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Reappraisal of the sequence stratigraphy of the Humber Group of the UK Central Graben

Pamela J. Sansom
Reappraisal of the sequence stratigraphy of the Humber Group of the UK Central Graben (in Petroleum geology; from mature basins to new frontiers; proceedings of the 7th petroleum geology conference, B. A. Vining (editor) and S. C. Pickering (editor))
Petroleum Geology Conference Series (2010) 7: 177-211

Abstract

Deposition of the Callovian-Ryazanian Humber Group of the UK Central Graben occurred during rifting and long-term relative sea-level rise, which acted to suppress the formation of eustatically forced Exxon-type sequence boundaries. The superposition of highly variable halokinetically controlled subsidence means that classic, passive-margin derived sequence stratigraphic models are not appropriate to describe stratigraphic evolution in this rift setting. The sequence stratigraphy of the Humber Group has been re-evaluated using a transgressive-regressive sequence model, where maximum regressive surfaces are employed as sequence bounding surfaces. The Humber Group comprises two megasequences which reveal distinct phases of evolution of the basin. The latest Callovian-Kimmeridgian megasequence comprises a conformable sequence stack which lacks significant internal unconformities and records progressive marine flooding and overall backstepping onto the basin flanks during a phase of active rifting. The Volgian-Ryazanian megasequence is condensed and highly fragmentary due to punctuation by a number of unconformities which are consistently recognizable throughout the basin. The onset of this change in architectural style corresponds to the oldest unconformity at the base of the Volgian-Ryazanian succession, termed the Base Volgian-Ryazanian Unconformity, of latest Kimmeridgian to earliest Volgian age. The patterns of erosion of the Callovian-Kimmeridgian megasequence and the intra Volgian-Ryazanian unconformities record the effects of dramatic redistribution of underlying salt accompanied by probable uplift of the Forties-Montrose High and J Ridge, resulting in major modification of the basin morphology and the severing of possible earlier links with the Fisher Bank Basin. The kinematics of this event are equivocal, but it is possible that restricted Volgian-Ryazanian depocentres resulted from localized salt collapse rather than basement extension. Widespread erosion of Callovian-Kimmeridgian Humber Group sediments may have occurred in some areas where Volgian-Ryazanian Kimmeridge Clay deposits now overlie pre-Jurassic strata, and exploration models must incorporate the effects of Volgian reconfiguration in order to accurately predict reservoir distribution.


ISSN: 2047-9921
Serial Title: Petroleum Geology Conference Series
Serial Volume: 7
Title: Reappraisal of the sequence stratigraphy of the Humber Group of the UK Central Graben
Title: Petroleum geology; from mature basins to new frontiers; proceedings of the 7th petroleum geology conference
Author(s): Sansom, Pamela J.
Author(s): Vining, B. A.editor
Author(s): Pickering, S. C.editor
Affiliation: BG Group, Berkshire, United Kingdom
Affiliation: Baker Hughes, London, United Kingdom
Pages: 177-211
Published: 2010
Text Language: English
Publisher: The=Geological Society of London, London, United Kingdom
ISBN: 978-1-86239-298-4
Meeting name: 7th petroleum geology conference; petroleum geology; from mature basins to new frontiers
Meeting location: London, GBR, United Kingdom
Meeting date: 20090330March 30-April 2, 2009
References: 41
Accession Number: 2012-023131
Categories: Economic geology, geology of energy sourcesStratigraphy
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., charts, geol. sketch maps
N51°00'00" - N61°10'00", W04°00'00" - E11°00'00"
Secondary Affiliation: Schlumberger, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute.
Update Code: 201213
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