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Sequence stratigraphy, chemostratigraphy and facies analysis of Cambrian Series 2 – Series 3 boundary strata in northwestern Scotland

FAGGETTER, LUKE E.; WIGNALL, PAUL B.; PRUSS, SARA B.; RAINE, ROBERT J.; NEWTON, ROBERT J.; JOACHIMSKI, MICHAEL M.; SMITH, PAUL M.; WIDDOWSON, MIKE; Faggetter, Luke; Joachimski, Michael; Pruss, Sara; Raine, Robert; Smith, Paul; SUN, YADONG; Wignall, P B

Authors

MIKE WIDDOWSON

YADONG SUN

LUKE E. FAGGETTER

PAUL B. WIGNALL

SARA B. PRUSS

ROBERT J. RAINE

ROBERT J. NEWTON

MICHAEL M. JOACHIMSKI

PAUL M. SMITH

Abstract

Globally, the Series 2 – Series 3 boundary of the Cambrian System coincides with a major carbon isotope excursion, sea-level changes and trilobite extinctions. Here we examine the sedimentology, sequence stratigraphy and carbon isotope record of this interval in the Cambrian strata (Durness Group) of NW Scotland. Carbonate carbon isotope data from the lower part of the Durness Group (Ghrudaidh Formation) show that the shallow-marine, Laurentian margin carbonates record two linked sea-level and carbon isotopic events. Whilst the carbon isotope excursions are not as pronounced as those expressed elsewhere, correlation with global records (Sauk I – Sauk II boundary and Olenellus biostratigraphic constraint) identifies them as representing the local expression of the ROECE and DICE. The upper part of the ROECE is recorded in the basal Ghrudaidh Formation whilst the DICE is seen around 30m above the base of this unit. Both carbon isotope excursions co-occur with surfaces interpreted to record regressive–transgressive events that produced amalgamated sequence boundaries and ravinement/flooding surfaces overlain by conglomerates of reworked intraclasts. The ROECE has been linked with redlichiid and olenellid trilobite extinctions, but in NW Scotland, Olenellus is found after the negative peak of the carbon isotope excursion but before sequence boundary formation.

Journal Article Type Article
Publication Date 2018-05
Journal Geological magazine
Print ISSN 0016-7568
Electronic ISSN 1469-5081
Publisher Cambridge University Press (CUP)
Peer Reviewed Peer Reviewed
Volume 155
Issue 04
Pages 1-13
DOI https://doi.org/10.1017/s0016756816000947
Keywords Durness Group, ROECE, DICE, Trilobite extinction, Scotland
Publisher URL https://www.cambridge.org/core/journals/geological-magazine/article/div-classtitlesequence-stratigraphy-chemostratigraphy-and-facies-analysis-of-cambrian-series-2-series-3-boundary-strata-in-northwestern-scotlanddiv/C34BD618A3A3D0810CC7DF0567990704
Additional Information This article has been published in a revised form in Geological magazine http://dx.doi.org/10.1017/S0016756816000947 . This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. © copyright holder.

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