The evolution and hydrocarbon potential of the Northumberland–Solway Basin

Abstract

Seismic and well data establish the three-dimensional geometry and structural evolution of the Northumberland–Solway Basin. The basin-controlling southerly bounding normal faults, the E–W-trending Maryport–Stublick–Ninety Fathom fault system, formed in early Carboniferous times by extensional reactivation of a major basement thrust zone. The faults are sub-planar with a present-day throw (at the base of the Carboniferous) of <4 km. Other important Dinantian syn-sedimentary normal faults trend roughly NNE-SSW and suffered dominantly oblique-slip displacements. Extension and syn-sedimentary faulting accompanied deposition of the Lower and Middle Border groups. Thereafter, until late Westphalian times, sedimentation was mainly in response to regional thermal relaxation subsidence. The maximum thickness of Carboniferous rocks ranges from around 5000 m in the Northumberland Trough to about 7000 m in the Solway Basin. At the end of Carboniferous times, the basin was partially inverted by Variscan transpression, with preferential reversal of the NNE-trending faults and the development of major monoclinal and anticlinal folds. Locally, there is evidence of embryonic syn-depositional folding in late Namurian times. In the Solway area, a Permo-Triassic to Jurassic succession, locally over 1.5 km thick, rests with marked angular unconformity on the Carboniferous strata. The argillaceous rocks of the basin commonly have high TOC values but are dominantly gas prone. The reservoir potential of the interbedded limestones and sandstones is poor. Most strata at outcrop are in the oil window, but in some boreholes, or where the rocks have been metamorphosed by the Whin Sill, overmature values have been recorded. Peak hydrocarbon generation was in late Westphalian times, prior to inversion, although some post-Variscan generation is possible in the Solway area, where there are oil and gas shows.

Single- and two-phase fluid flow properties of cataclastic fault rocks in porous sandstone

“…The fault system down-throws to the north and constitutes the southern border of the Carboniferous Northumberland-Solway Basin, which covers around 6500 km 2 of northern England and southern Scotland (Chadwick et al, 1993). In NE England, the Stublick-90-Fathom fault system represents the border between the early Carboniferous Northumberland basin to the north and the Alston block, a granite-centred structural high, to the south (Collier, 1989;Kimbell et al, 1989;Fig.…”

Palaeogeography of tropical seasonal coastal wetlands in northern Britain during the early Mississippian Romer's Gap

“…Volcanism accompanied opening of the Tweed and Northumberland–Solway basins (Leeder 1974a; Chadwick et al . 1995). The early sedimentary fill to the basins comprises the Ballagan Formation, which was preceded by the upper Devonian Kinnesswood Formation and succeeded in various parts of the region by the Clyde Sandstone, Garleton Hills Volcanic, Lyne and Fell Sandstone formations (Figs 1, 2).…”

“…Approximately 520m occur in the Tweed Basin whereas in the Northumberland–Solway Basin Tournaisian and Chadian strata may be up to 3400m thick in the centre of this asymmetric graben (Chadwick et al . 1995). The formation is absent from the central part of the Midland Valley, having been eroded during mid-Visean (Arundian) uplift prior to the Clyde Plateau volcanism (Millward & Stephenson 2011).…”

“…Outcrop data from the British Geological Survey DiGMapGB© NERC 2015; subcrop extent in the Northumberland–Solway basin from Chadwick et al . (1995). …”

Controls of coalbed methane prospectivity in Great Britain

“…The following reviews give further details: Read (1988) and Francis (1991) (Midland Valley of Scotland); Scott & CoRer (1987) and Chadwick et al (1993) (Northumberland-Solway Basin); Besly (1988) andWaters et al (1994) (west and southwest of the Pennines); and Fraser et al (1990) (east of the Pennines and general).…”