The palaeoenvironments and stratigraphy of the Lincolnshire Limestone Formation (Middle Jurassic: Bajocian) of Northamptonshire and southern Lincolnshire

Abstract

The Lincolnshire Limestone Formation, which crops out in eastern England from the Humber south for over 100 kilometres, is well exposed in the study area in the quarries of Cowthick, Clipsham, Copper Hill and Brauncewell. Nine members recognised by previous authors in this formation can be distinguished on gross lithology within this southern region, the lateral and vertical changes in carbonate lithology being indicative of a complex of marginal marine shallow-water environments. A macrofauna dominated by gastropods (but associated with bivalves, bryozoa, rare brachiopods and fragmentary echinoderms) has been recorded from several horizons within the complex stratigraphy sampled at Cowthick, three horizons at Clipsham, three of eight samples at Copper Hill, but is not known from Brauncewell. A low diversity microfauna of ostracods and benthic foraminifera is known from more of the sampled horizons at Clipsham and Copper Hill and up to four horizons at Brauncewell. This fauna has not been recorded at Cowthick. The ostracod Praeschuleridea subtrigona occurs with other species characteristic of the Pneumatocythere carinata (ostracod) Subzone, consistent with parts of the (ammonite) Laeviuscula Zone age ascribed to at least part of the strata by earlier authors. The size distributions and morphological forms displayed by the ostracod and foraminifera faunas suggest periods of vegetative cover on the sea floor, periods of sediment anoxia and the reworking of material from adjacent sedimentological environments at Clipsham, Copper Hill and Brauncewell. Sedimentological breaks between members and individual beds have allowed previous authors to correlate over distances in the study area, this technique has allowed a temporal link to be suggested between the erosion of Aalenian deposits and the deposition of material and both Cowthick and Copper Hill

Date of Award	2001
Original language	English
Awarding Institution	University of Northampton
Supervisor	Gavin K Gillmore (Supervisor)