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dc.date.accessioned2013-08-01T10:28:28Z
dc.date.available2013-08-01T10:28:28Z
dc.date.issued2012en_US
dc.date.submitted2012-12-03en_US
dc.identifier.citationGuttormsen, Julie. Sedimentology, paleontology and diagenesis of the Ordovician (Darriwilian) Svartodden Member (Huk Formation), Slemmestad, Oslo Region. Masteroppgave, University of Oslo, 2012en_US
dc.identifier.urihttp://hdl.handle.net/10852/34355
dc.description.abstractSvartodden leddet i Huk Formasjonen ved Slemmestad, Buskerud, har blitt undersøkt for å beskrive avsetningsmiljøet i området da sedimentene ble avsatt under tidsperioden Ordovicium. Svartodden leddet er rikt på endoceratide blekksprut fossiler, og arten Proterovaginoceras incognitum er den mest dominerende. Bergarten er en 2 m tykk kalksten, som samsvarer med den nedre delen av den Baltoskandiske Orthoceras kalken. Her er flere såkalte hard- og firmgrounds tidligere beskrevet, og disse ble blant annet på grunn av en særdeles lav sedimentasjonshastighet og tidlig sementering. Funn av Thalassinoides-aktige graveganger laget av trilobitter fra slekten asaphus og sporfossiler av typen Thalassinoides bacae er blitt identifisert i leddet. Mikrostromatolitter er også identifisert i bergarten. Elementkonsentrasjoner av Fe, S, Mn og P gjennom leddet ble kartlagt ved hjelp av en XRF kjernescanner, og funnene ble sammenliknet mot mulige firm- og hardgrounds observert i en polert kjerne av leddet. De observerte firmgrounds er antatt å ha blitt utviklet i sammenheng med anrikning av fosfor, pga. en opphoping av organisk materiale på havbunnen. Prøver av bergarten ble løst opp med svak eddiksyre, og det gjenværende materialet ble undersøkt for innhold av conodonter, autigene mineraler og mikrotektitter. Funn av de karakteristiske conodont artene typiske for biosonen Eoplacognathus pseudoplanus, Drepanodus arcuatus og Baltoniodus medius ble funnet i Svartodden leddet. Fosfatiserte brachiopoder fra slektene Conotreta og Myotreta, i tillegg til bryozoer fra slektene Moyerella, Chasmatopora og Moorephylloporina ble også identifisert under studien.nor
dc.description.abstractThe Ordovician (Darriwilian) Svartodden Member of the Huk Formation in the village of Slemmestad in the Oslo Region, Norway, is characterized by large and abundant orthoconic endocerid cephalopods. Proterovaginoceras incognitum is the most dominant species recorded in the Svartodden Mbr. The Svartodden Mbr. is a 2 m thick limestone unit, corresponding to the lower part of the Baltoscandic Orthoceratite Limestone, characterized by several hard- and firmgrounds formed as a result of a very low net sedimentation rate and by early cementation. The main part of the fieldwork performed in this study was conducted at the well-known outcrop near the Slemmestad IF arena, a bedding surface measuring approximately 1300 m2. The unit was carefully logged with a particular focus on detecting firm- and hardgrounds. The macrofauna was recorded and the different cephalopod species were quantified. Current directions based on orientations of cephalopod conchs show a preferential current from an N-E direction. Extensive bioturbation can be witnessed from abundant trace fossils on the main bedding surface. Tunneling asaphid trilobites took advantage of the firmgrounds and produced most of the abundant Thalassinoides trace fossils contained in the unit. The main cause for this opportunistic behavior is linked to predation pressure from the abundant omnivorous nautiloid cephalopods. The tunnels are believed to have been inhabited by microstromatolites, forming microbial linings growing from the tunnel peripheries. New records and interpretations of firm- and hardgrounds based on field observations and element analysis by x-ray fluorescence (XRF) of the bulk unit are presented. Element concentrations of Fe, S, Mn and P are used to recognize the hardgrounds. The data suggest that firmgrounds evolved in combination with enrichment of phosphorus, which may be linked to cyclicities of upwelling. Slabs were dissolved in acetic acid, and the acid resistant residue was analysed with respect to microfossils, authigenic minerals and microtektites. The recorded conodont species Drepanodus arcuatus and Baltoniodus medius are characteristic species of the Ecoplacognathus pseudoplanus zone, also previously reported from the Svartodden Mbr. Brachiopods belonging to the genera Conotreta and Myotreta, as well as bryozoans of the genera Moyerella, Chasmatopora and Moorephylloporina have also been recorded. These new findings have shed light on the depositional environment and the fauna contained in the Svartodden Mbr. Isotopic composition of 13C and 18O has been recorded. The diagenetic history of the unit based on studies of cements in cephalopod siphuncles, includes several stages of precipitation and dissolution of cements most lightly caused by alternating burial and uplift. Major dolomitization and formation of pyrite is believed to have formed at different levels of burial, in the shallow and deep relam.eng
dc.language.isonoben_US
dc.titleSedimentology, paleontology and diagenesis of the Ordovician (Darriwilian) Svartodden Member (Huk Formation), Slemmestad, Oslo Regionen_US
dc.typeMaster thesisen_US
dc.date.updated2013-07-25en_US
dc.creator.authorGuttormsen, Julieen_US
dc.subject.nsiVDP::450en_US
dc.identifier.bibliographiccitationinfo:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft.au=Guttormsen, Julie&rft.title=Sedimentology, paleontology and diagenesis of the Ordovician (Darriwilian) Svartodden Member (Huk Formation), Slemmestad, Oslo Region&rft.inst=University of Oslo&rft.date=2012&rft.degree=Masteroppgaveen_US
dc.identifier.urnURN:NBN:no-33045en_US
dc.type.documentMasteroppgaveen_US
dc.identifier.duo174000en_US
dc.contributor.supervisorHans Arne Nakrem, Øyvind Hammer and Krzysztof Hryniewiczen_US
dc.identifier.bibsys132390418en_US
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/34355/1/final-Julie-Guttormsen.pdf


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