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/S0016756810000464Before downloading, please read NORA policies.
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.
|Programmes:||BGS Programmes 2010 > NERC Isotope Geoscience Laboratory|
|Date made live:||05 Jan 2011 15:34|
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