The stratigraphy and carbonate environments of the Lincolnshire Limestone Formation (Bajocian) in Lincolnshire and parts of Leicestershire

The Lincolnshire Limestone Formation (Bajocian) of eastern England has been studied from three standpoints: biostratigraphy, lithostratigraphyand environmental analysis. New discoveries and a revision of earlier ammonte finds have permitted a re-assessment of the formation's age relative to the standard Jurassic ammonite zonal scheme. Three distinct ammonite faunas, representative of the discites Zone, and ovalis and laeviuscula Subzones of the laeviuscula Zone, have been recognised. It has therefore been possible, for the first time, to subdivide the formation on the basis of its ammonite faunas. As neither the lowest nor highest lithostratigraphic units have so far yielded any ammonites, the minimum and maximum ages of the Lincolnshire Limestone remain unresolved.The lithostratigraphy of the formation has been completely revised and eleven "formalised" members proposed: Sproxton, Greetwell, lsadenham, Lincoln, Scottlethorpe, Lindsey Shale, Metheringham, Blankney, Castle Bytham, Sleaford and Creeton. The base of the Lincoln Member is considered to be of fundamental importance in the internal correlation of the formation. It has been used as the datum level for all correlations. As the boundary between the ammonite faunas indicative of the discites and laeviuscula Zones appears to coincide with the base of the Lincoln Member, it may well be a significant biostratigraphic, as well as lithostratigraphic divide. Although less certain on present evidence, the base of the Sleaford Member may also prove to be an important biostratigraphic boundary, separating the ammonite fauna of the ovalis and laeviuscula Subzones of the laeviuscula Zone.Analysis of both sedimentological and faunal criteria has permitted a number of environments to be recognised. In broad terms the transgressive Lincolnshire Limestone sequence has prograding tidal-flat rhythms and "lagoonal" deposits erosively overlain by barrier-complex sediments. Various sub-environments, including barrier-inlet channels and barrier-island sediments, have been recognised within the barrier-complex