Svend Stouge

Upper Furongian (Cambrian) conodonts from the Degerhamn quarry road section, southern Öland, Sweden

The Alum Shale Formation exposed at the Degerhamn quarry road section, southern Öland, Sweden, contains a diversified assemblage of euconodonts, paraconodonts and protoconodonts, the majority of which have ranges confined to the Furongian Series (Cambrian). The first occurrence (FO) of the cosmopolitan euconodont species Proconodontus muelleri is recorded in the uppermost part of the Ctenopyge spectabilis trilobite Zone and the first appearance datum of Cordylodus? andresi is in the upper part of the Parabolina lobata trilobite Zone. Three new successive paraconodont associations are introduced: (1) the Furnishina Association, (2) the Prooneotodus Association and (3) the Westergaardodina Association, which, respectively, correspond to deeper marine, deep marine and shallow marine conditions. The genus Stenodontus Chen & Gong is revised in multielement taxonomy. New species formally named are Furnishina holmi and Westergaardodina asinina; Furnishina sp. A and Furnishina sp. B are described in open nomenclature.

Chapter 56 Neoproterozoic (Cryogenian–Ediacaran) deposits in East and North-East Greenland

Abstract The Neoproterozoic succession of East and North-East Greenland (over 14 000 m thick) includes the Eleonore Bay Supergroup (?Tonian–Cryogenian) and the Tillite Group (Cryogenian–Ediacaran). The upper units of the Eleonore Bay Supergroup consist of shallow to deeper-water carbonates, succeeded by siliciclastic fine-grained sediments (Bedgroup 19) that characterize the top unit of the supergroup. The Tillite Group includes two diamictite-bearing units (Ulvesø and Storeelv formations) of glaciogenic origin and two upper, upwards-shallowing strata (Canyon and Spiral Creek formations) that were deposited during semiarid conditions and concluded the Neoproterozoic depositional cycle. Diamictite is preserved on the craton and compares with the Storeelv Formation (Fm.) of the Tillite Group. Detailed investigations of the diamictite-bearing units (i.e. Ulvesø and Storeelv formations) demonstrate that the lower of the two formations is mainly of marine origin, whereas the upper one has both marine and terrestrial origins. Chemostratigraphic data include analyses on total carbon (TC), total organic carbon (TOC), total sulphur (TS) and δ13C. The data set for δ13C shows a substantial and abrupt shift towards negative values of ≥10%, from below Bedgroup 19. Low-diversity acritarch assemblages (Cryogenian) are recorded from the Andrée Land and Tillite groups; a thin cherty dolostone unit present above the Storeelv Fm. suggests that the diamictite units are of late Cryogenian age and the upper part of the Tillite Group is Ediacaran. Bedgroup 19 disconformably overlies older carbonates and the unit is a prelude to the succeeding (upper Cryogenian–lower Ediacaran) diamictite sediments of the Tillite Group. A disconformity separates the Tillite Group from the overlying Lower Palaeozoic sediments. Both disconformities are, according to palaeomagnetic data, related to rift–drift episodes that occurred during the late Neoproterozoic. Alternatively, the isotope data suggest that the diamictites were deposited during the late Cryogenian glaciation and the older disconformity may be interpreted as a significant gap developed by the lowering of sea level during an early Cryogenian glaciation.

Lower palaeozoic stratigraphy of Murchisonfjorden and Sparreneset, Nordaustlandet, Svalbard

Stouge, S., Christiansen, J.L. and Holmer, L.E., 2011. Lower Palaeozoic stratigraphy of Murchisonfjorden and Sparreneset, Nordaustlandet, Svalbard. Geografiska Annaler: Series A, Physical Geography, 93, 209–226. DOI: 10.1111/j.1468‐0459.2011.00433.x Abstract The Lower Palaeozoic stratigraphy of the Kap Sparre Formation of Kulling (Hecla Hoek Succession) from Murchisonfjorden and eastern Nordaustlandet of Svalbard is described based on new field observations in the region. The investigated sedimentary succession is referred to the Upper quartzite series and Upper dolomite series of the Kap Sparre Formation. The observed sequence resembles that of the Oslobreen Group from central and northeastern Ny Friesland and the formal and well‐established and more detailed stratigraphical framework used in Ny Friesland may apply for the strata at Sparreneset and in Murchisonfjorden, western Nordaustlandet. The lower Palaeozoic succession overlies the uppermost Precambrian sediments (Dracoisen Formation = the lower part of Kap Sparre Formation sensu Kulling) of the Polarisbreen Group with a cryptic unconformity, and a regional stratigraphical gap spanning the late Ediacaran developed on the platform. Additions to the previous descriptions of some of the existing units are presented. The new lithostratigraphical unit: Black shale and limestone unit is proposed informally. It is a Lower(?) to Middle Cambrian black shale with limestone nodules and lenses that is exposed on the northwest coast of Krossøya in Murchisonfjorden, Svalbard. In addition, a Dolostone‐limestone unit, Middle(?) Cambrian to Lower Ordovician, composed of dolostone and dolomitized limestone and minor limestone, and a Limestone unit (Lower to Middle(?) Ordovician), which overlies the Upper dolomite series are added to the succession. The deposits as a whole show the development of an environmentally controlled carbonate platform that marked the transition from the inner to the outer shelf that evolved during the opening and spreading of the Iapetus Ocean.

Development of the Lower Cambrian–Middle Ordovician Carbonate Platform: North Atlantic Region

The northeastern margin of Laurentia formed an important part of the Iapetus Ocean and includes the development of the Franklinian Basin in North Greenland and Arctic Canada. The uninterrupted continental margin bordering the North American craton is represented by well-exposed successions in Northeast and eastern North Greenland, together with Svalbard and Bjornoya. Physiographically, the northeastern margin of Laurentia during the early Paleozoic history of Greenland was a northward extension of the passive rifted continental margin of the Caledonian continental edge of Laurentia. It was a transform-rifted margin and represents the part of the Laurentian margin that borders the Arctic part of the North Atlantic Ocean. Geologically, the northwestern segment of the continental margin has a somewhat different setting and development from farther south in the Northeast Greenland–Svalbard segment but both regions overlie a thick and extensive package of Neoproterozoic rocks and were affected by the Caledonian orogeny.

Trace fossils from the lower Cambrian Kløftelv Formation, Ella Ø, North-East Greenland

Abstract Relatively large burrows with crudely-developed spreiten, some arranged in a zig-zag pattern, occur in the Kløftelv Formation, Ella Ø, North-East Greenland. These trace fossils, tentatively identified as Teichichnus isp., are associated with sedimentary structures which include microbial mat-related sand cracks that support earlier interpretations of a near-shore marine setting for the formation. The combination of morphological features apparent in these trace fossils confirm previous assignments of the Kløftelv Formation to the Cambrian, but excluding the basal-most Cambrian. The Kløftelv Formation has been typically correlated with other siliciclastic units in the North Atlantic region with a comparable basal position in a transgressive succession, which in their upper parts have dense assemblages of Skolithos. These are interpreted to have formed during a rapid transgression over a low-angle passive margin of the Iapetus Ocean. The trace fossils described here also provide the first direct evidence that the lower part of the basal siliciclastics is of Cambrian age.

Early Ordovician (Skullrockian) trilobites of the Antiklinalbugt Formation, northeast Greenland, and their biostratigraphic significance

Abstract The Antiklinalbugt Formation of northeast Greenland comprises peritidal to subtidal carbonate sediments, deposited in shallow shelf settings during an early Tremadocian transgressive-regressive megacycle. The succession of shales and microbial, muddy and grainy limestone, with minor dolostone at the base and top, terminates at the cryptic Fimbulfjeld disconformity. The formation has yielded trilobites collected on Ella Ø, Albert Heim Bjerge, and Kap Weber by C. Poulsen (1920s and 1930s), J. W. Cowie and P. J. Adams (1950s), and during recent field studies in 2000 and 2001. The fauna includes dimeropygids Tulepyge cowiei and T. tesella n. spp., hystricurids Millardicurus and Hystricurus, and several species of Symphysurina. Micragnostus chiushuensis (Kobayashi, 1931) is rare, as are Chasbellus sp., Clelandia sp., and Lunacrania?. The presence of several Symphysurina species places the Antiklinalbugt Formation within the Symphysurina Zone. Chasbellus indicates the upper (lower Ordovician) part of the Symphysurina Zone for the lower upper Antiklinalbugt Formation. Conodonts place the middle lower formation in the Cordylodus intermedius conodont Biozone, the lower upper part in the Cordylodus angulatus conodont Biozone and the uppermost part in the Rossodus manitouensis conodont Biozone. This combined fauna is characteristic of the upper Skullrockian Stage of the Ibexian Series, with the lower part of the Antiklinalbugt Formation lying within the uppermost Cambrian of North America, and the upper part within the lower Ordovician. The entire formation lies within the global Tremadocian Stage of the early Ordovician.

Lower Ordovician trilobites from the Septembersø formation, North-East Greenland

McCobb, L.M.E., Boyce, W.D., Knight, I. & Stouge, S., 2014. Lower Ordovician trilobites from the Septembersø formation, North-East Greenland. Alcheringa 38, 575–598. ISSN 0311-5518. The informally named Septembersø formation is a 76 m thick succession of microbial and peritidal shelf carbonates deposited on the North-East Greenland shelf of Laurentia. The formation, assigned to the lower part of the Cape Weber Formation in all previous studies, lies disconformably upon the Skullrockian Antiklinalbugt Formation (revised) and conformably below the Tulean to Blackhillsian Cape Weber Formation (revised) in the Fimbulfjeld Group. With the exception of Randaynia, the modest trilobite fauna recovered from the Septembersø formation consists exclusively of bathyurids, and all represent new species. Both Chapmanopyge knudseni sp. nov. and Punka adamsi sp. nov. are represented by sufficient material to merit specific names. The remaining taxa, belonging to Bolbocephalus, Peltabellia, Randaynia and Chapmanopyge are left in open nomenclature. The trilobite genera present suggest that the Septembersø formation is referable to the Tulean Stage of the Ibexian Series, latest Tremadocian/earliest Floian in Global Standard terms. Lucy M. E. McCobb [lucy.mccobb@museumwales.ac.uk], Department of Natural Sciences, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK; W. Douglas Boyce [dougboyce@gov.nl.ca] and Ian Knight [ianknight@gov.nl.ca], Geological Survey, Newfoundland and Labrador Department of Natural Resources, PO Box 8700, St. John’s, NL, Canada A1B 4J6; Svend Stouge [svends@snm.ku.dk], Natural History Museum of Denmark (Geological Museum), Øster Voldgade 5–7, DK-1350 Copenhagen K, Denmark.