Abstract Carboniferous rocks within the Cumbria and northern Pennines region are bound by the Maryport-Stublick-Ninety Fathom Fault System, which forms the northern boundary of the Lake District and Alston blocks (Fig. 37). In the Pennines, the succession occupies the Alston and Askrigg blocks and the intervening Stainmore Trough, a broadly east-west trending graben. Carboniferous strata also flank the Lake District Block, occurring at outcrop in north Cumbria, Furness and Cartmel (south Cumbria) and the Vale of Eden, and in the subsurface in west Cumbria. The Askrigg Block succession is separated from that of the Craven Basin (Chapter 11), to the south, by the Craven Fault System. All of the stages of the Carboniferous, with the exception of the Stephanian, are present at outcrop. The oldest Tournaisian strata occur at outcrop along the flanks of the Lake District Block and within the Stainmore Trough. They are represented by continental and peritidal deposits (Ravenstonedale Group), and locally associated with volcanic rocks (Cockermouth Volcanic Formation of north Cumbria). The Ravenstonedale Group is diachronous, occurring later on the structural highs, with deposition during Chadian times on the Askrigg Block and Holkerian times on the Alston Block. The Ravenstonedale Group is overlain by upper Tournaisian to upper Visean platform carbonate rocks (Great Scar Limestone Group), which initially developed on the flanks of the Lake District Block, but by late Asbian times extended across the entire region (Mitchell 1978).

Abstract Intrusive igneous rocks contributed very significantly to crustal growth in northern England and the English Midlands during Ordovician and Devonian times, and the buoyancy effect of these mainly granitic rocks beneath the Lake District, Cheviot Hills and the Askrigg and Alston areas of the north Pennines was to have a profound effect on the later development of Carboniferous and Permo-Triassic extensional basins in the region. During late Ordovician times voluminous subduction- related intrusive rocks were emplaced at the margin of Eastern Avalonia in a zone extending at least from Ireland, through the Lake District and the Midlands, to Belgium as a result of closure of the Iapetus Ocean and Tornquist Sea. By contrast, Early Devonian granitic plutons in northern England and the Southern Uplands belong to suites that were emplaced across the Iapetus suture zone, before, during and after the Acadian Orogeny. A similar sequence may be present in the Isle of Man. In the Lake District, the main components of a large, subvolcanic, granitic batholith ( Fig. 7.1 ), along with a wide variety of minor intrusions, were emplaced contemporaneously with the Caradoc Eycott and Borrowdale volcanic groups (Millward 2002, 2004 and references therein). Some of the exposed intrusions are linked geochemically to the volcanic rocks, whereas others have distinctive geochemical signatures (e.g. O’Brien et al. 1985). To the SE, within the Askrigg Block and in central England, late Ordovician calc-alkaline intrusive and volcanic rocks comprise a relatively small number of exposures