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dc.contributor.authorJones, S.M.
dc.contributor.authorPrave, A.R.
dc.contributor.authorRaub, T.D.
dc.contributor.authorCloutier, J.
dc.contributor.authorStüeken, E. E.
dc.contributor.authorRose, C.V.
dc.contributor.authorLinnekogel, S.
dc.contributor.authorNazarov, K.
dc.identifier.citationJones , S M , Prave , A R , Raub , T D , Cloutier , J , Stüeken , E E , Rose , C V , Linnekogel , S & Nazarov , K 2020 , ' A marine origin for the late Mesoproterozoic Copper Harbor and Nonesuch Formations of the Midcontinent Rift of Laurentia ' , Precambrian Research , vol. 336 , 105510 .
dc.identifier.otherPURE: 263520783
dc.identifier.otherPURE UUID: 6209cbe8-84af-4f06-a32b-3ffb9b0e5362
dc.identifier.otherRIS: urn:EEF07978995850D4FCB9E80E2A8A1B79
dc.identifier.otherScopus: 85074660390
dc.identifier.otherORCID: /0000-0002-4614-3774/work/65013838
dc.identifier.otherORCID: /0000-0002-9432-9880/work/65014386
dc.identifier.otherORCID: /0000-0001-6861-2490/work/65014397
dc.identifier.otherORCID: /0000-0001-8149-0977/work/65014453
dc.identifier.otherWOS: 000508748600014
dc.identifier.otherORCID: /0000-0003-4513-2245/work/84315167
dc.descriptionThis work was supported by First Quantum Minerals Ltd., Vancouver, Canada.en
dc.description.abstractThe c. 1.1 Ga Copper Harbor and Nonesuch Formations of the Keweenawan Supergroup exposed along the Canadian-United States shorelines of Lake Superior are part of the surface exposures of the Laurentian Midcontinent Rift. These units have long been considered non-marine in origin and have figured prominently in ideas regarding the evolution of microbial life and the redox conditions of Earth’s ocean-atmosphere system at the close of Mesoproterozoic time. However, these rocks also host hydrothermal metal deposits, the emplacement of which may have compromised primary geochemical signals that are used to underpin those ideas. Here we highlight new sedimentological observations to provide an independent framework for assessing the depositional setting and geochemistry of those strata. We show that the totality of sedimentological features leads to the conclusion that parts of the upper Copper Harbor Formation and the entirety of the Nonesuch Formation were deposited along tide- and wave-influenced shorelines and in shallow-marine settings under evaporitic conditions. Evidence for this interpretation includes the abundance of flaser, wavy, linsen and pinstripe bedding, ubiquity of reactivation surfaces and mud drapes associated with all ripple forms, superposed sets of ripple cross-lamination showing bimodal (herring-bone) sediment transport directions, desiccation cracks and metre-scale hummocky cross-stratification. Further, evaporite fabrics and pseudomorphs after gypsum in the upper 200 m of the Copper Harbor Formation and in numerous stratigraphic positions within the Nonesuch Formation indicate that the water body was saline, not fresh. The emerging palaeogeographic image is one of a large, shallow-marine embayment with fringing sabkha-like shorelines. Ideas about late Mesoproterozoic biospheric evolution and Earth’s surface redox and oxygenation that rely on the Nonesuch Formation and Copper Harbor stromatolites having been deposited within a lacustrine setting require reassessment.
dc.relation.ispartofPrecambrian Researchen
dc.rightsCopyright © 2019 Elsevier B.V. All rights reserved. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at
dc.subjectMidcontinent Riften
dc.subjectKeweenawan Supergroupen
dc.subjectCopper Harbor Formationen
dc.subjectNonesuch Formationen
dc.subjectGE Environmental Sciencesen
dc.subjectSDG 14 - Life Below Wateren
dc.titleA marine origin for the late Mesoproterozoic Copper Harbor and Nonesuch Formations of the Midcontinent Rift of Laurentiaen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews. Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Sustainability Instituteen
dc.contributor.institutionUniversity of St Andrews. St Andrews Isotope Geochemistryen
dc.contributor.institutionUniversity of St Andrews. Marine Alliance for Science & Technology Scotlanden
dc.contributor.institutionUniversity of St Andrews. St Andrews Centre for Exoplanet Scienceen
dc.description.statusPeer revieweden

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