The Grampian and Appin groups of the southwestern Monadhliath Mountains form the earliest known syn-rift sequences of the Scottish central Highlands. They were likely to have formed in an intracontinental setting and represent deposition of mixed clastic and carbonate shallow and deep marine strata. The Grampian Group of the southern Monadhliath Mountains was deposited during a period of initial basin rifting (NW–SE extension) followed by a phase of thermal subsidence. Syn-rift sediments comprise a 2.5–6 km thick turbidite system. Thermal subsidence brought about the basinward progradation of shallow marine shelf sediments resulting in the infilling of pre-existing basin topography. The overlying Appin Group commenced with deposition of a shallow marine sequence alternating between nearshore tidal sand and offshore mud deposition. This formed in response to renewed rifting and concomitant subsidence. Accelerated rifting resulted in localized footwall uplift and erosion while sedimentation continued in the hanging-wall areas. Resultant subsidence, perhaps partly thermally driven, caused gradual basin widening and produced an onlapping marine sequence. There followed a period of progressive clastic deprivation when carbonates were precipitated, and at the onset of anoxic conditions, deposition of organic muds. The fundamental structural elements responsible for the formation of the Grampian and Appin group basins were also influential in the orogenic evolution of the basin-fill. Half-graben fills were deformed to produce regionally extensive folds such as the Stob Ban–Craig a’ Chail Synform.

The presence of strata of Westphalian A to possibly Stephanian age in south Staffordshire, located at the southern margin of the Pennine Basin, provides a rare control on the timing of late Carboniferous deformation in Central England. During Westphalian A—C times, sedimentation in south Staffordshire was controlled by thermal subsidence, with a superimposed influence of synsedimentary normal and reverse faulting. Alkaline basic igneous activity occurred during Westphalian C times, synchronous with uplift of the southern margin of the Pennine Basin. Uplift culminated, during Westphalian C—D times, in a phase of Variscan inversion along basement lineaments and the development of a regional unconformity. Renewed subsidence and deposition of a relatively thick sedimentary sequence of Westphalian D to possibly Stephanian age was followed by a final phase of Variscan deformation, comprising possibly two pulses of uplift, tilting and erosion. Observations presented for south Staffordshire, in conjunction with studies from other parts of the Pennine Basin, indicate a complex interrelationship between rifting, thermal subsidence and Variscan basin inversion. Pulses of N—S extension and E—W to NW—SE compression are interpreted as the product of regional strike-slip deformation, superimposed upon a regime of thermal subsidence. Alkaline igneous activity is considered to be the product of mantle partial melting in response to limited decompression due to transtensional displacements on crustal thickness faults.

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A stratigraphic framework is proposed for the Late Proterozoic Grampian Group of the Scottish Highlands. The Grampian Group is divided into three subgroups, each defined by distinctive lithofacies associations reflecting different environments of deposition. The thin Ord Ban Subgroup, which is locally developed at the base of the Grampian Group on Speyside and Strath Dearn, consists of shallow marine shelf sediments in association with concordant amphibolite sheets. Elsewhere the Corrieyairack Subgroup, which is thickest around Loch Laggan, forms the lower portion of the Grampian Group and comprises a thick turbiditic clastic sequence laid down in deeper water during rapid basin subsidence. The Glen Spean Subgroup comprises the upper part of the Grampian Group and is thickest in the Atholl District. It is composed of shallow water tidal and deltaic deposits, marking a shallowing of the Grampian Group basin. Lateral facies changes and diachronous contacts are indicative of differential subsidence and the Grampian Group basin apparently developed and filled before the onset of regional subsidence which heralded deposition of the overlying Dalradian sediments. The possibility that the Grampian Group was unconformable on the structurally underly-ing Central Highland Division and Glenshirra Succession is currently unresolved.

Sediments of the Halesowen and Salop Formations (Westphalian D-Stephanian) in the West Midlands were deposited on the southern margin of the Pennine Basin during a period of relative tectonic quiescence during the Variscan Orogeny. The clastic framework of the predominantly red sandstones and mudstones in the Salop Formation includes large detrital hematite grains; these yield a primary component of magnetization indicating that sediments were deposited close to the Carboniferous palaeo-equator. Variscan uplift, erosion and subsequent deep oxidation in an arid climate during the Permian resulted in the precipitation of finer hematite in rocks of both formations (which are now found at depths of over 150 m below the present-day ground level). These grains carry secondary magnetizations which indicate formation at palaeolatitudes of between 5° and 15°N, the position that Britain occupied during the Permian. The pattern of Permian remagnetization (particularly in borehole samples) suggests that the secondary fine-grained hematite was precipitated as a result of lateral flow of meteoric water through connected, permeable sandstone units, rather than downward percolation through the entire succession. Present-day surface weathering has resulted in the dissolution of the finer grains of hematite and, in some cases, where permeabilities are relatively high, it has also affected the coarser fraction. Consequently, the record of late Carboniferous and Permian magnetization events is commonly incomplete in strata close to the present day ground level.