Stratigraphy of the Upper Carboniferous Schooner Formation, Southern North Sea: Chemostratigraphy, Mineralogy, Palynology and Sm–Nd Isotope Analysis
Stratigraphy of the Upper Carboniferous Schooner Formation, southern North Sea: chemostratigraphy, mineralogy, palynology and Sm–Nd isotope analysis T. J. Pearce,1 D. McLean,2 D. Wray,3 D. K. Wright,4 C. J. Jeans,5 E. W. Mearns6 1, 4: Chemostrat Ltd, Units 3 & 4, Llanfyllin Enterprise Park, Llanfyllin, Powys, SY22 5DD 2: Palynology Research Facility, Department of Animal and Plant Sciences, Western Bank, Sheffield, S10 2TN 3: Department of Earth Sciences, University of Greenwich, Chatham Maritime, Kent, ME4 4TB 5: Department of Earth Sciences, Cambridge University, Downing Street, Cambridge, CB2 3EQ 6: Isotopic Ltd, Craigiebuckler House, Macaulay Drive, Aberdeen, AB15 8QH Summary The continental, predominantly redbed sequences of the Upper Carboniferous Schooner Formation (“Barren Red Measures”) from the southern North Sea represent a significant gas reservoir, but, as they are largely devoid of microfossils, interwell corre- lations are difficult. The stratigraphy of the formation is re-evaluated by applying a multidisciplinary approach, which includes chemostratigraphy, mineralogy, palynology, Sm–Nd isotopes, petrophysics and sedimentology, to well 44/21-3, as it has encountered a thick, relatively complete section through the Schooner Formation. The formation is divided into three chemo- stratigraphical units (S1, S2 and S3) and eleven sub-units on the basis of variations in the mudstone and sandstone data, these variations being linked to changes in provenance, depositional environment and climate. The chemostratigraphical zonation is compared with the biostratigraphical zonation of the same section – heavy-mineral data confirm the sediment source, and Sm– Nd isotope data provide a provenance age for the well 44/21-3 interval. The correlation potential of the new stratigraphical frame- work is tested on several scales, using data acquired from other southern North Sea wells and from Upper Carboniferous strata of the English Midlands.
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