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GEOREF RECORD

The biostratigraphy of the upper Pliensbachian-Toarcian (Lower Jurassic) sequence at Ilminster, Somerset

I. Boomer, A. R. Lord, K. N. Page, P. R. Bown, F. M. D. Lowry and J. B. Riding
The biostratigraphy of the upper Pliensbachian-Toarcian (Lower Jurassic) sequence at Ilminster, Somerset
Journal of Micropalaeontology (May 2009) 28, Part 1: 67-85

Abstract

Temporary road sections for the A303 bypass at Ilminster, Somerset, revealed Upper Pliensbachian and Toarcian sediments from an alternating limestone-marl facies, in marked contrast to the limestone-dominated Dorset coast succession. The lithostratigraphy is described, with the standard ammonite zonation providing chronostratigraphical correlation. The uppermost Pliensbachian (Spinatum Chronozone) and much of the Toarcian (Serpentinum, Bifrons, Variabilis, Thouarsense and Pseudoradiosa chronozones) of the classic Dorset coast Lower Jurassic sequence are represented by the Beacon Limestone Formation, formerly the 'Junction Bed' (a highly condensed carbonate deposit). The Tenuicostatum Chronozone is largely missing from the sequence. Elsewhere in southern and eastern England this interval is poorly or rarely exposed. The argillaceous units have yielded rich microfaunas and -floras (foraminifera, ostracods, calcareous nannofossils and palynomorphs), the biostratigraphical distributions of which are analysed and discussed in relation to contemporary evolutionary patterns and other UK records. This study provides an insight into the micro-biostratigraphy of the Late Pliensbachian to Toarcian interval for onshore southern England.


ISSN: 0262-821X
EISSN: 2041-4978
Serial Title: Journal of Micropalaeontology
Serial Volume: 28, Part 1
Title: The biostratigraphy of the upper Pliensbachian-Toarcian (Lower Jurassic) sequence at Ilminster, Somerset
Affiliation: University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham, United Kingdom
Pages: 67-85
Published: 200905
Text Language: English
Publisher: British Micropalaeontological Society, London, United Kingdom
References: 79
Accession Number: 2011-011302
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. strat. cols., 1 table, sketch map
N60°55'60" - N60°55'60", W02°53'60" - W02°53'60"
Secondary Affiliation: Forschungsinstitut Senckenberg, DEU, GermanyUniversity of Plymouth, GBR, United KingdomUniversity College London, GBR, United KingdomUniversity of Greenwich, GBR, United KingdomBritish Geological Survey, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201108
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