Upper Jurassic stratigraphy of four shallow cored boreholes in the U.K. sector of the southern North Sea

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Abstract
SUMMARY: Four shallow cored boreholes (81/41, 81/43, 81/47 and 81/49) in the southern North Sea area (U.K. Quadrants 42 and 47) proved Upper Jurassic mudstone sequences which compare closely in lithological and macrofaunal detail with the well known Kimmeridge Clay succession of southern and eastern England. Although together the boreholes do not give complete stratigraphical coverage, all the Kimmeridgian standard ammonite zones from Baylei to Hudlestoni are represented; in Borehole 81/43, beds of the Hudlestoni Zone are unconformably overlain by Lower Cretaceous strata. Thicknesses in boreholes 81/41 and 81/43 are comparable with those proved on the onshore East Midlands Shelf, but those in 81/47 and 81/49 appear to be two or three times thicker; these relationships fit the known disposition of the Sole Pit Basin. Borehole 81/41 also cored 21.1m of Middle to Upper Oxfordian strata. The ostracod faunas and dinoflagellate cyst floras are discussed and range charts of selected taxa presented. The foraminifera are also considered.