Carboniferous geology of the Southern North Sea Basin and controls on hydrocarbon prospectivity

Abstract

The thick sequences of Upper Palaeozoic strata present in the Southern North Sea Basin were probably deposited on a basement of Caledonian low-grade metamorphic rocks intruded by numerous late-Caledonian granitoids which form part of the subsurface extension of the Mid-European Caledonides linking the English Lake District and Northern Pennines to the Ardennes. This basement, along with the better known onshore areas of the British Isles and Ireland was intensely fragmented during late Devonian to mid-Carboniferous times by a major phase of extensional tectonics.Active fault-bounded tilted blocks developed in the Dinantian with deposition of fluviatile redbeds, marine carbonate/deltaic clastic cycles and deltaic coastal plain facies. These are penetrated by a number of wells on the southern flanks of the Mid-North Sea High, but details of basin geometries and facies distributions remain unclear.Crustal stretching appears to have given way to thermal subsidence by early to midNamurian times. This was coincident with a major climatic change, probably forced by glacial expansion in Gondwanaland. Thc major drainage system that resulted dominated sedimentation in the SNSCB, punctuated by numerous marine transgrcssions of undoubted glacio-eustatic origins. Within this broad dcpositional framework, Namurian facies were closely controlled by basement tilt block topography, with good cvidcncc for a gradual southerly migration of the active fairways of fluviodeitaic sandbodies. Wcstphalian facies were dominated by the interplay between glacio-eustatic and sedimentary processes on a vast low-gradient alluvial plain with much less pronounced tectonic control.By latc-Wcstphalian B timcs a phase of basin inversion caused thc gradual clcvation of thc arca as a rctro-arc forcland basin. Vadosc diagencsis and pcdogcncsis occurred in the fluviatilc facies of thc so-called Barrcn Rcd Mcasurcs (BRM). With continucd comprcssivc dcformation a scrics of over 50 NW-SE oricntatcd folds, somc associated with thrusts, dcvcloped. Significant crosion and truncation of these invcrsion anticlincs was accompanicd by thc deposition of thc BRM facies in characteristic growth fold basins, with marked onlap around thc basin margins. The Carboniferous play in thc SNSCB has been greatly influcnccd by thc subsequent Mcsozoic/Cenozoic geological history of the basin, including periods of subsidcncc and uplift. Wc demonstrate that variations in original detrital mineralogy and various diagcnetic processes havc cxcrted significant controls upon Carbonifcrous reservoir quality.

Warwickshire Group (Pennsylvanian) red-beds of the Canonbie Coalfield, England–Scotland border, and their regional palaeogeographical implications

“…In several parts of northern England and in the southern North Sea, it has been suggested that deposition of the latest part of the basin-fill was contemporary with the early phases of the Variscan Orogeny and that many of the folds are in part syndepositional (e.g. Leeder & Hardman, 1990;Chadwick et al 1995, p. 36;Corfield et al 1996). Within the study area, Chadwick et al (1995, fig.…”

“…Murdoch and Ravenspurn anticlines), which formed as a result of late Carboniferous regional compressional tectonics (Leeder & Hardman, 1990). Besly, Burley & Turner (1993) suggested that the Ketch Formation formed contemporaneously with the evolving Variscan foreland basin, with sediment derived as a result of Variscan uplift.…”

Architectural analysis of a Triassic fluvial system: The Sherwood Sandstone of the East Midlands Shelf, UK

“…The Southern Permian Basin developed in response to crustal extension during initial stages of the break-up of Pangaea (Ziegler, 1988). The basin is characterised by east-west extension and some associated syn-depositional faulting has been speculated (Leeder and Hardman, 1990). This broad area of sediment accumulation stretched across much of northwest Europe towards modern-day Poland (Doornenbal and Stevenson, 2010).…”

Permo-Carboniferous plays of the Silver Pit Basin

“…The Silver Pi{ Basin (with the Cleveland Basin) was the site of thick Namurian sedimentation (Leeder and Hardman 1990), with 2000 m of Namurian present in the central part. Deltaic deposits are found mainly on the southern flank of the Mid North Sea High and over the Proto-Inde Ridge.…”