Lithostratigraphy and biostratigraphy of the Lower Carboniferous (Mississippian) carbonates of the southern Askrigg Block, North Yorkshire, UK

Abstract

A rationalized lithostratigraphy for the Great Scar Limestone Group of the southeast Askrigg Block is established. The basal Chapel House Limestone Formation, assessed from boreholes, comprises shallow-marine to supratidal carbonates that thin rapidly northwards across the Craven Fault System, onlapping a palaeotopographical high of Lower Palaeozoic strata. The formation is of late Arundian age in the Silverdale Borehole, its northernmost development. The overlying Kilnsey Formation represents a southward-thickening and upward-shoaling carbonate development on a south-facing carbonate ramp. Foraminiferal/algal assemblages suggest a late Holkerian and early Asbian age, respectively, for the uppermost parts of the lower Scaleber Force Limestone and upper Scaleber Quarry Limestone members, significantly younger than previously interpreted. The succeeding Malham Formation comprises the lower Cove Limestone and upper Gordale Limestone members. Foraminiferal/ algal assemblages indicate a late Asbian age for the formation, contrasting with the Holkerian age previously attributed to the Cove Limestone. The members reflect a change from a partially shallow-water lagoon (Cove Limestone) to more open-marine shelf (Gordale Limestone), coincident with the onset of marked sea-level fluctuations and formation of palaeokarstic surfaces with palaeosoils in the latter. Facies variations along the southern flank of the Askrigg Block, including an absence of fenestral lime-mudstone in the upper part of the Cove Limestone and presence of dark grey cherty grainstone/packstone in the upper part the Gordale Limestone are related to enhanced subsidence during late Asbian movement on the Craven Fault System. This accounts for the marked thickening of both members towards the Greenhow Inlier.

Foraminifers of the Viséan–Serpukhovian boundary interval in Western Palaeotethys: a review

“…This interval might extend up to the MH2 sequence in the Mikhailovian in the Moscow Basin, which also includes the FOD of Koskinobigenerina prisca , a species which is also present as early as the late Asbian in Western Europe (Somerville ; Waters et al . ).…”

“…Both species seem to first occur at equivalent levels in the latest Asbian or just at the Asbian/Brigantian boundary (Jones & Somerville ; Cózar & Somerville ; Somerville ; Waters et al . ). Endothyranopsis ( Reitlingeropsis ) sphaerica , another marker of the Mikhailovian (although considered as a zonal marker for the Eostaffella tenebrosa – E .…”

“…The concept of Neoarchaediscus is confusing in the literature, and other taxa, partly occluded by nodes, first occur from the middle Viséan, and even, locally, from the top of the early Viséan in Western Europe (Waters et al . ), but the FOD of Neoarchaediscus remains poorly known. In Eastern Europe, this group is no less ambiguous, because N. parvus is documented from the Aleksian in the Moscow Basin, whereas it is used as a marker for the Serpukhovian in the Ukraine (Vdovenko ).…”

“…Thus, for Conil et al (1977Conil et al ( , 1980Conil et al ( , 1991 and Poty et al (2006), the genus Neoarchaediscus characterizes the entire late Vis ean, although the genus was only illustrated from the late Warnantian and Brigantian. The concept of Neoarchaediscus is confusing in the literature, and other taxa, partly occluded by nodes, first occur from the middle Vis ean, and even, locally, from the top of the early Vis ean in Western Europe (Waters et al 2017), but the FOD of Neoarchaediscus remains poorly known. In Eastern Europe, this group is no less ambiguous, because N. parvus is documented from the Aleksian in the Moscow Basin, whereas it is used as a marker for the Serpukhovian in the Ukraine (Vdovenko 2001).…”

“…4) than in Western Europe, where it is only known from the upper part of the late Asbian (Cf6c2 of Jones & Somerville 1996) or upper V3bc of Vachard (1977). This interval might extend up to the MH2 sequence in the Mikhailovian in the Moscow Basin, which also includes the FOD of Koskinobigenerina prisca, a species which is also present as early as the late Asbian in Western Europe (Somerville 2008;Waters et al 2017).…”