Controls on deltaic sedimentation in glacio-eustatic cycles of late Marsdenian (Namurian R _2b 4 to R _2c 1, Pennsylvanian) age in the UK Central Pennine Basin

Abstract

Summary Evolution of the succession between the Bilinguites eometabilinguis (R 2b 4) and Verneulites sigma (R 2c 2) marine bands of Marsdenian (Pennsylvanian) age in the Central Pennine Basin, and its offshore extension into the North Sea Basin, is discussed. Five separate marine bands are now recognized. Two closely spaced marine bands, B. eometabilinguis and B. metabilinguis , occur at the base of the R 2b 4 cycle and a higher B. metabilinguis band occurs at the base of the R 2b 5 cycle. The overlying B. superbilinguis and V. sigma marine bands define an additional thinner and much simpler cycle (R 2c 1). These three cycles are all of glacio-eustatic origin. A new sequence-stratigraphic interpretation examines the relationship between the constituent sandstone units (currently named the Hazel Greave Grit, Beacon Hill Flags, Guiseley Grit, Ashover Grit, Roaches Grit, plus local names and unnamed units). Different types of fluvial-deltaic sequences were deposited in different phases of the cycle and some cycles lack coarse clastic lithologies. The succession in parts of Yorkshire and Lancashire contains a major non-sequence in the R 2b 5 cycle. A revised interpretation of the incised deep channels in the Roaches Grit in Staffordshire, suggesting river channel adjustment to a post-glacial climate rather than infill of a pre-eroded palaeovalley, is also presented. Many of these different features can be explained by climatic variations associated with the Carboniferous Ice Age. Variations in basin bathymetry and fault related subsidence exercised more localized controls.

Bottomset Architecture Formed In the Troughs of Dunes and Unit Bars

“…The North Staffordshire Basin formed in the Late Devonian to early Carboniferous by north-south extension, and was in a phase of thermal subsidence by the Namurian (Leeder 1982(Leeder , 1988Waters et al 2008). This, along with rapid glacioeustatic sea-level variation (Jones and Chisholm 1997;Jones 2014) controlled the sedimentary architecture.…”

Climatic Influences on Upper Carboniferous (Serpukhovian to Mid-Bashkirian) Sedimentary Sequences in the UK Pennine and Other European Basins

“…Amongst the various cyclothems supplied by the Caledonian River System in Northern England up to three distinctive fluvial and deltaic sequences have been recognized (Table 2, Figure 5, Figure 6). Each developed at a different time in the evolution of the cyclothem [74]. This classification is slightly different from an earlier classification [75], which was based more on the depth of water into which the deltas prograded.…”

“…1) Type 1 delta sequences formed from lobate deltas developed during the earliest phases of delta progradation and are locally present in almost all of the observed cyclothems (see [76] (Pendleian) and [77] (Westphalian B) for more detailed sedimentology descriptions). Other descriptions are given in [74] [78]- [83]. Many of the delta sequences are dominated by mouth bar deposits and are predominantly composed of very fine to medium-grained sandstones.…”

“…Lower Middleton Grit [12]. Parts of the Beacon Hill Flags (Type 2b) (Cyclothem M8, R2b5) have wavy lamination towards the top with parallel and current current ripple lamination with rare small scale trough cross-beds lower down [74].…”

“…In rare cases (Type 2e) the mouth bar facies is poorly developed, and channel deposits predominate [86]. Trace fossil variety and abundance varies greatly; some mouth bar sequences such as the Beacon Hill Flags showing a wide variety of marginal marine types [74] whereas others are dominated by Pelecypodichnus (a.k.a Lockeia), the resting and escape traces of non-marine bivalves [87]. Distributary channels in Type 1 delta sequences typically form sandbodies at least 1km wide which may show highly divergent paleocurrent orientations [74] [76] [78] [88] [89], suggesting a radial distributary pattern.…”