Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by McILROY, D.
Right arrow Articles by MOSELEY, J. B.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 1998; v. 155; issue.2; p. 401-411;
DOI: 10.1144/gsjgs.155.2.0401
© 1998 Geological Society of London

Article

The Proterozoic–Cambrian transition within the ‘Charnian Supergroup’ of central England and the antiquity of the Ediacara fauna

D. McILROY1,2, M. D. BRASIER1 & J. B. MOSELEY3

1 Department of Earth Sciences, Oxford University, Parks Road, Oxford OX1 3PR, UK (e-mail: martin.brasier{at}earth.ox.ac.uk)
2 Currently at: Department of Earth Sciences, University of Liverpool, Liverpool L69 3BX, UK
3 Dingle Nook, Shirley Lane, Longton, Preston PR4 5NJ, UK

A revised interpretation for the ‘Charnian Supergroup’ is suggested from ichnological and lithological comparisons with the Cambrian of Nuneaton and other parts of the Avalonian superterrane. Late Neoproterozoic volcaniclastic sediments contain an Ediacara fauna in the Maplewell Group. These are succeeded by one or more inferred erosional breaks and overlain by passive margin sediments (quartzarenites, glauconitic greywackes, pelites) of the Brand Group which yield Cambrian trace fossils, including abundant large Teichichnus. This transformation is compared with that between the Neoproterozoic Caldecote Volcanic Formation and the Cambrian Hartshill Formation at Nuneaton. The Hanging Rocks Formation of the Brand Group lies above a major erosional break but shares a volcanogenic island arc petrology with the underlying Maplewell Group. Conglomeratic sandstones at the base of the Brand Hills Formation contain purple pelite clasts comparable with underlying lithologies, plus clasts of weathered diorite showing granophyric textures identical to those seen in the enigmatic South Charnwood Diorites. Nd–Sm isotope studies confirm the geochemical similarity between these diorites and those that intruded the Caldecote Volcanics at Nuneaton, previously U–Pb zircon dated at 603±2 Ma. These strong similarities with the Nuneaton succession suggest that deposition of the Brand Hills Formation in the Cambrian was preceded by the local unroofing of diorite and erosion of underlying mudrocks, much as seen in other parts of Avalonia. A date of 603±2 Ma for the South Charnwood Diorites provides a minimum age for the local Ediacara fauna but this is in need of substantiation.

Key Words: Proterozoic • Precambrian • Cambrian • Ediacara • ichnofossils




This article has been cited by other articles:


Home page
 Geological MagazineHome page
J. N. CARNEY, P. ALEXANDRE, M. S. PRINGLE, T. C. PHARAOH, R. J. MERRIMAN, and S. J. KEMP
40Ar-39Ar isotope constraints on the age of deformation in Charnwood Forest, UK
Geological Magazine, 2008; 145: 702 - 713.
[Abstract] [Full Text] [PDF]

Home page
 Journal of the Geological SocietyHome page
W. Compston, W. COMPSTON, A. E. WRIGHT, and P. TOGHILL
Dating the Late Precambrian volcanicity of England and Wales
Journal of the Geological Society, 2002; 159: 323 - 339.
[Abstract] [Full Text] [PDF]