Early Neoproterozoic limestones from the Gwna Group, Anglesey

Horak, Jana M.; Evans, Jane A.. 2011 Early Neoproterozoic limestones from the Gwna Group, Anglesey. Geological Magazine, 148 (1). 78-88. 10.1017/S0016756810000464

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Official URL: http://geolmag.geoscienceworld.org/content/vol148/...

Abstract/Summary

Limestone megaclasts up to hundreds of metres in size are present within the Gwna Group mélange, North Wales, UK. The mélange has been interpreted as part of a Peri-Gondwanan fore-arc accretionary complex although the age of deposition remains contentious, proposals ranging from Neoproterozoic to Early Ordovician. This paper uses strontium isotope chemostratigraphy to establish the age of the limestone blocks and thus provide a maximum age constraint on mélange formation. Results show that, although the carbonates are locally dolomitized, primary 87Sr/86Sr ratios can be identified and indicate deposition sometime between the late Tonian and earliest Cryogenian. This age is older than that suggested by stromatolites within the limestone and indicates that the limestone did not form as cap carbonate deposits.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1017/S0016756810000464
Programmes:	BGS Programmes 2010 > NERC Isotope Geoscience Laboratory
ISSN:	0016-7568
Date made live:	05 Jan 2011 15:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/12963

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1017/S0016756810000464

Programmes:

BGS Programmes 2010 > NERC Isotope Geoscience Laboratory

ISSN:

0016-7568

Date made live:

05 Jan 2011 15:34 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/12963