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dc.contributor.authorPruss, Sara B.
dc.contributor.authorBosak, Tanja
dc.contributor.authorMacdonald, Francis Alexander
dc.contributor.authorMcLane, Marie
dc.contributor.authorHoffman, Paul
dc.date.accessioned2017-08-04T15:34:54Z
dc.date.issued2010
dc.identifier.citationPruss, Sara B., Tanja Bosak, Francis A. Macdonald, Marie McLane, and Paul F. Hoffman. 2010. “Microbial Facies in a Sturtian Cap Carbonate, the Rasthof Formation, Otavi Group, Northern Namibia.” Precambrian Research 181 (1-4) (August): 187–198. doi:10.1016/j.precamres.2010.06.006.en_US
dc.identifier.issn0301-9268en_US
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:33717507
dc.description.abstractMicrobial structures in Neoproterozoic cap carbonates record the environmental processes present in the aftermath of global glaciation. The Rasthof Formation of northern Namibia is a unique carbonate depositional sequence that formed during post-glacial transgression and highstand following the Chuos glaciation. Carbon isotope profiles from four examined localities reveal that onlap was diachronous over post-glacial, syn-rift topography. The lower Rasthof Formation consists primarily of dark gray thinly (<mm) and thickly (1–4 mm) laminated microbialites that exhibit different rheological responses to the emplacement of syndepositional dikes. The thinly laminated microbialaminite facies commonly host cm-sized syndepositional folds of microbially laminated sediment called roll-up structures. In more thickly laminated facies, layers are deformed into broad decimeter-sized folds, but roll-up structures are absent. Large syndepositional carbonate clastic dikes (0.5–1 m wide) and smaller veins (0.1–0.5 m) cut across bedding in both the thinly and thickly laminated facies, but are conspicuously absent from underlying and overlying beds. These carbonate clastic dikes and veins contain convoluted microbial mats and abundant marine cements. The lack of evidence for wave action or current scouring in the form of bedforms, scour marks, or intraclasts indicates that these microbialaminites formed below storm wave base. The close spatial association of deep-water microbialaminite facies in the Rasthof cap carbonate with carbonate clastic dikes suggests that the emplacement of dikes produced both dm-sized broad folds and cm-scale laterally discontinuous roll-up structures. The emplacement of the dikes, most likely due to the release of fluids into incompletely lithified mats, deformed cement-rich thick laminites into broad folds, while thinly laminated and more slowly lithifying mats were rolled into roll-up structures. Microbialaminite facies in the Rasthof cap carbonate thus not only reflect the depositional and environmental processes that operated in the aftermath of the Sturtian glaciation, but may also provide clues for the formation of roll-up structures found in even older Precambrian carbonates.en_US
dc.description.sponsorshipEarth and Planetary Sciencesen_US
dc.language.isoen_USen_US
dc.publisherElsevier BVen_US
dc.relation.isversionofdoi:10.1016/j.precamres.2010.06.006en_US
dc.relation.hasversionhttp://projects.iq.harvard.edu/files/fmacdonald/files/2010_microbial_facies.pdfen_US
dc.relation.hasversionhttp://francismacdonald.fas.harvard.edu/files/fmacdonald/files/2010_microbial_facies.pdfen_US
dash.licenseMETA_ONLY
dc.subjectCryogenianen_US
dc.subjectRoll-up structureen_US
dc.subjectNeoproterozoicen_US
dc.subjectMicrobialaminiteen_US
dc.subjectCap carbonateen_US
dc.subjectNamibiaen_US
dc.titleMicrobial facies in a Sturtian cap carbonate, the Rasthof Formation, Otavi Group, northern Namibiaen_US
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden_US
dc.relation.journalPrecambrian Researchen_US
dash.depositing.authorMacdonald, Francis Alexander
dash.embargo.until10000-01-01
dc.identifier.doi10.1016/j.precamres.2010.06.006*
workflow.legacycommentsFAR 2011 Macdonald emailed 2016-05-04 AD Macdonald emailed 2017-02-24 MM meta.darken_US
dash.contributor.affiliatedHoffman, Paul
dash.contributor.affiliatedMacdonald, Francis


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