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- Agic, Heda, et al.
(författare)
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Life through the 'Varanger ice ages' : microfossil record of late Neoproterozoic glacial-interglacial units from arctic Norway
- 2018
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Ingår i: Geological Society of America <em>Abstracts with Programs</em>. - : Geological Society of America.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The late Neoproterozoic strata in Finnmark (Arctic Norway) provide a good sedimentary record of Neoproterozoic glaciations on the Baltica paleocontinent. The lower Vestertana Group exposed on the Digermulen Peninsula contains two glaciogenic units, the Smalfjord and Mortensnes formations. Chemostratigraphic correlation dated the Smalfjord diamictite to the Marinoan glaciation (650-635 Ma), yet its age was also proposed to be older, per correlation to glacial units in central and southern Scandinavia. The diamictites are bracketing shales and siltstones of the interglacial Nyborg Formation. Stratigraphic, paleontological, and sedimentological data are presented from the interglacial-glacial succession, investigated by the Digermulen Early Life Research Group. Palynological analysis yielded well-preserved organic-walled microfossils (OWM) from the Nyborg Fm., and from fine-grained diamictite matrix in the Mortensnes Fm. via a modified extraction method.The interglacial Nyborg Fm. hosts a moderate diversity assemblage of prokaryotic and eukaryotic OWM, as well as acanthomorphic acritarchs such as Ceratosphaeridium, ?Cavaspina, and a novel process-bearing form. Organically preserved, enigmatic multicellular eukaryotic fossils occur in the upper Nyborg Fm. The Mortensens glacial assemblage is less diverse and contains bacterial filaments, leiosphaerids, toroidal forms, and Micrhystridium-type minute acanthomorphs.The presence of Doushantuo-Pertatataka type acritarchs in the Nyborg Fm., and small acanthomorphs in the Mortensnes diamictite corroborate an early Ediacaran age for the interglacial-glacial succession on Digermulen. In addition to the trace fossil and body-fossil record of Ediacara-biota in the overlying Stáhpogieddi Formation, the microfossil biostratigraphy suggests Marinoan and Gaskiers glaciation equivalent ages of the Varanger glaciations in Finnmark. Protistan diversity in the succession declined through and following the glaciation, until late Ediacaran.
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| 2. |
- Agić, Heda, 1989-, et al.
(författare)
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Organically-preserved multicellular eukaryote from the early Ediacaran Nyborg Formation, Arctic Norway
- 2019
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Eukaryotic multicellularity originated in the Mesoproterozoic Era and evolved multiple times since, yet early multicellular fossils are scarce until the terminal Neoproterozoic and often restricted to cases of exceptional preservation. Here we describe unusual organically-preserved fossils from mudrocks, that provide support for the presence of organisms with differentiated cells (potentially an epithelial layer) in the late Neoproterozoic. Cyathinema digermulense gen. et sp. nov. from the Nyborg Formation, Vestertana Group, Digermulen Peninsula in Arctic Norway, is a new carbonaceous organ-taxon which consists of stacked tubes with cup-shaped ends. It represents parts of a larger organism (multicellular eukaryote or a colony), likely with greater preservation potential than its other elements. Arrangement of open-ended tubes invites comparison with cells of an epithelial layer present in a variety of eukaryotic clades. This tissue may have benefitted the organism in: avoiding overgrowth, limiting fouling, reproduction, or water filtration. C. digermulense shares characteristics with extant and fossil groups including red algae and their fossils, demosponge larvae and putative sponge fossils, colonial protists, and nematophytes. Regardless of its precise affinity, C. digermulense was a complex and likely benthic marine eukaryote exhibiting cellular differentiation, and a rare occurrence of early multicellularity outside of Konservat-Lagerstatten.
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| 5. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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Biostratigraphy and palaeontology of the lower Cambrian Duolbagáisá Formation on the Digermulen Peninsula, Arctic Norway
- 2018
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Ingår i: International Conference on Arctic Margins.
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Konferensbidrag (refereegranskat)abstract
- The lower Cambrian sequence on the Digermulen Peninsula (Finnmark, Arctic Norway) is the northernmost extension of the Cambrian deposits along the Caledonian front. It is exceedingly thick compared to cratonal successions typical of most of Baltica. The Duolbagáisá Formation represents the youngest lower Cambrian unit on the peninsula with the first trilobite-bearing strata, a plethora of trace fossils including diverse arthropod traces and Plagiogmus arcuatus, and abundant and wellpreserved organic walled microfossils (OWM). Extensive field work by the Digermulen Early Life Research Group allows for the first time a detailed appreciation of the age and faunal composition of the unit. The lower member is ~250 m thick with thin-bedded siltstone, sandstone and mudstone. A single unidentifiable holmiid thorax region occurs alongside arthropod trace fossils. OWM indicate the S. ornata-F. membranacea Zone. The upper member is ~390 m thick and consist of several upward shallowing parasequences with fine-grained sandstone, siltstone and mudstone followed by thick mature quartzite. The trace fossil Syringomorpha occurs throughout the upper member and Cruziana and Rusophycus are especially abundant in the upper parts. The first identifiable olenellid trilobites occur in a thick mudstone/siltstone interval at the middle of the member, along with an elliptocephalid trilobite and other arthropods. Abundant OWM indicate the H. dissimilare-S. ciliosa Zone with the higher levels belonging to the Volkovia-Liepaina Zone. The entire sequence thus span the Cambrian Series 2, stages 3–5.
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| 6. |
- Ebbestad, Jan Ove R., et al.
(författare)
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Distribution and correlation of Sabellidites cambriensis (Annelida?) in the basal Cambrian on Baltica
- 2021
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Ingår i: Geological Magazine. - Cambridge : Cambridge University Press (CUP). - 0016-7568 .- 1469-5081. ; 159:7, s. 1262-1283
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Tidskriftsartikel (refereegranskat)abstract
- Sabellidites cambriensis is a tubular non-mineralized metazoan that appears as compressed ribbon-shaped imprints with transverse wrinkling, thick walls and an even tube diameter of up to 3 mm. The distribution of Sabellidites is investigated in three Ediacaran–Cambrian sections on the Digermulen Peninsula in Arctic Norway, spanning the Manndrapselva Member of the Stáhpogieddi Formation and the lower member of the Breidvika Formation. Here, the Ediacaran–Cambrian boundary is located in the lower part of the upper parasequence (third cycle) of the Manndrapselva Member. Specimens of Sabellidites are rare but consistently present close to the lowest level of Treptichnus pedum and upsection, whereas the taxon is common and abundant in the lower part of the lower member of the Breidvika Formation, with an upper record at c. 55 m above the base. The range is comparable with that of the GSSP section in Newfoundland, Canada, establishing Sabellidites as an index fossil for the lowermost Cambrian. In the Manndrapselva Member, Sabellidites co-occurs with the acritarch Granomarginata, indicative of the lowermost Cambrian Granomarginata Zone, whereas in the Breidvika Formation it co-occurs with Asteridium. Sabellidites is widely distributed in Baltica, through the Rovnian and Lontovan regional stages but confined to the Fortunian global stage. In its lower range, Sabellidites is associated with a Treptichnus pedum trace fossil association and a depauperate leiosphaerid acritarch assemblage, followed by a Granomarginata assemblage. In its upper range, Sabellidites co-occurs with acritarchs of the Asteridium–Comasphaeridium Zone and the tubular foraminiferan Platysolenites. In Baltica, Sabellidites is a useful index fossil.
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| 8. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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Holmiid trilobites from the lower Cambrian of the Digermulen Peninsula, Arctic Norway
- 2017
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Ingår i: 6th International Conference on Trilobites and their Relatives. Tallinn, Estonia, 7-10 July 2017. - Tallinn : Libris Est OU. - 9789949818617
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Konferensbidrag (refereegranskat)abstract
- Lower Cambrian holmiid olenelloids are used for biozonation of lower Cambrian (Series 2) strata in Baltoscandia. About a dozen species have been named since the description of Holmia kjerulfi (Linnarsson, 1868), but except for the classical area in Mjøsa, Norway, the species traditionally occur in small numbers, are variably preserved, occur at one or a few localities only and usually with only one taxon present. Definitions of the biozones are therefore still problematic. One level in the lower Cambrian Duolbasgáissá Formation of the Digermulen Peninsula, Arctic Norway, has yielded more than 50 new specimens of holmiids, preliminarily assigned to Elliptocephala n. sp. and Kjerulfia n. sp. Acritarchs indicate the Heliosphaeridium dissimilare–Skagia ciliosa acritarch Zone which corresponds to the traditional Holmia kjerulfi Assemblage Zone. Elliptocephala n. sp. is known from about a dozen specimens. It is characterized by very long palpebral lobes, a parallel-sided glabella, a short anterior glabellar lobe and short genal spines. A node is developed on the occipital ring. Semi-complete specimens show up to 10 thoracic segments, but the full number of thoracic segments and the pygidium is unknown. The slightly older E. lundgreni (Moberg, 1892), known from the Schmidtiellus mickwitzi Zone of southern Sweden, differs in the proportions of the glabella, the length of the palpebral lobes and definition of the cephalic border. Both H. mobergi and H. sulcata from Sweden show similarities to Elliptocephala n. sp. in the weakly developed lateral border with an effaced anterior border furrow. Nikolaisen & Henningsmoen (1987) described Kjerulfia lata Kiær, 1917 from two fragmentary specimens from this locality in Digermulen. More than 20 new specimens from this site shows that the species differs from Kjerulfia lata from the type area in southern Norway in proportions and features of the glabella, the width of the genal field and the possession of a stout and high spine on the occipital ring, and it is tentatively assigned to Kjerulfia n. sp. The material from the Digermulen Peninsula adds to the diversity of the Baltoscandian holmiids and is tightly constrained stratigraphically.
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| 10. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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Stratigraphy of the Ediacaran and basal Cambrian of the Digermulen Peninsula, Northern Norway
- 2015
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Ingår i: Geological Society of America Abstracts with Programs, vol 47.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The succession of the Digermulen Peninsula in Finnmark, northern Norway, is the only fossiliferous site inScandinavia with sedimentation across the Ediacaran–Cambrian transition without a significant hiatus. Geologicalinvestigations started in the 1930’s, but the Peninsula was first mapped in the 60’s. Ediacara-type fossils werefirst discovered in the late 80’s but recent discoveries will establish the Digermulen Peninsula as one of the mostsignificant Ediacaran sites in northern Europe. The parautochthonous strata are exposed in the Tanafjord areaalong the coast and in valleys on the east side of the Peninsula. The beds dip slightly to the west with the strikefollowing the coastline (ca. 045°). The Ediacaran succession is close to 1000 m thick and dominantly siliciclastic.It starts with interglacial sediments of the Nyborg Formation (tentatively the earliest Ediacaran), overlying astacked succession of diamictites of the Cryogenian Smalfjord Formation. After a hiatus follows the glaciogenicdiamictites of the Mortensnes Formation (~60 m thick), which is commonly seen to represent the ~582 Ma-oldGaskiers glaciation. Upwards, the contact to the overlying Stáhpogiedde Formation is not exposed locally, but hasbeen shown to represent a hiatus followed by transitional fluvial to marine sediments of the Lillevannet Member.Ediacaran-type fossils appear in the succeeding Innerelva Member. This is a two-cycle deepening upwardssuccession of laminated mudstone with intercalated sand bodies showing load structures. Preliminary microfossilssamples of the Member have so far proven almost barren, making dating more challenging. The basal part of thesucceeding Manndraperelva Member consists of three cycles; first a succession of reddish sandstone followed bytwo coarsening-upward cycles. Each starts with mudstone and fine sandstone and terminates in cross-beddedsandstone. The Ediacaran–Cambrian boundary is located within the third cycle, identified by the trace fossilTreptichnus pedum and associated trilobed trace fossils.The Digermulen Early Life Research Group has since2011 made significant new finds, and focused fieldwork aims to resolve tighter age constraints, provenance of thesediments and the range and diversity of the extended Ediacaran biota.
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