Brachiopod associations from the Middle Ordovician of the Oslo Region, Norway

Abstract

The marine upper Darriwilian (Middle Ordovician) Elnes Formation of southern Norway contains very rich and diverse invertebrate faunas. Stratigraphically detailed recent collections of these well-preserved faunas have permitted a more thorough description of the various faunal groups and their preferences in the late Middle Ordovician of the Oslo Region, southern Norway, than ever before. The brachiopod faunas are described in the present article, which include a new genus and a new species respectively Wandaasella modheimrensis and Cyclomyonia vikersundi. The brachiopod fauna is largely dominated by linguliformeans although some sections of the formation are dominated by the plectambonitoids Alwynella ildjernensis Spjeldnaes or Cathrynia aequistriata (Hadding) or by orthid brachiopods. Statistical analysis of the brachiopod fauna reveals that the general depositional trend of the Elnes Formation is that of a regressive event from the lower part of the Sjøstrand Member to the Håkavik Member. Three main brachiopod associations are recognised: a deep-water, lingulid dominated association associated with quiet and dysoxic bottom conditions, a sowerbyellid dominated association (e.g. Cathrynia and Alwynella) found in muddy to marly deposits formed around maximal storm wave base and an orthid-dominated association representing an environment characterised by a fairly coarse or hard bottom substrate formed well above storm wave base but below fair weather wave base.

U–Pb age and Lu–Hf signatures of detrital zircon from Palaeozoic sandstones in the Oslo Rift, Norway

“…2; e.g. Hansen, 2008; Candela & Hansen, 2010) and in the latest Ordovician period (Brenchley, Newall & Stanistreet, 1979; Brenchley & Newall, 1980) has been interpreted to reflect sedimentary response to the growing Caledonian mountain chain to the NW of the Oslo Region (Bjørlykke, 1974; Bruton, Gabrielsen & Larsen, 2010). A land area to the NW, which sheltered the foreland basin from the Iapetus Ocean (Hansen, 2008, 2009), is thought to have been an important source of siliciclastic material to the Oslo Region during the Late Ordovician period (Størmer, 1967; Brenchley, Newall & Stanistreet, 1979; Bruton, Gabrielsen & Larsen, 2010).…”

BroeggeriaWalcott and other upper Cambrian and Tremadocian linguloid brachiopods from NW Argentina

“…The youngest species of the genus, B. fimbriatus (Hadding, ), from the upper Darriwilian‐lower Sandbian of Norway and Sweden, can readily be distinguished from all other Broeggeria species in possessing marginal spines. In addition, B. fimbriatus differs from B. omaguaca in its elongate shell outline and narrower ventral platform (Candela and Hansen, ).…”

“…The Elnes Formation in the Olso region, Norway, contains varied brachiopod assemblages of Darriwilian age. By using Q‐mode and R‐mode cluster analyses, Candela and Hansen () recognized a ‘lingulid association’ in which Broeggeria fimbriatus Candela and Hansen is very common (more than 40% of the total). Unlike the above‐mentioned records, in this formation, Broeggeria has been recorded in different facial contexts, from agitated shallow waters to dark‐grey graptolitic mudstones.…”

“…Unlike the above‐mentioned records, in this formation, Broeggeria has been recorded in different facial contexts, from agitated shallow waters to dark‐grey graptolitic mudstones. For instance, Broeggeria fimbriatus also integrates the low‐diversity Cathrynia ‐lingulid and Alwynella ‐lingulid associations present in low‐energy mud‐dominated environments above or around storm wave‐base, but according to Candela and Hansen (), it inhabited preferably deep‐water slightly dysoxic bottoms.…”

A Middle Ordovician (Darriwilian) Dysaerobic Brachiopod Assemblage from the Precordillera Terrane of Argentina: Implications for Early Colonization of Deep Waters

“…This latitudinal movement is reflected by a large-scale change from cold-water siliciclastic sediments to warm-water tropical carbonates (Dronov and Rozhnov, 2007). The thorough paleoecological analysis carried out by Candela and Hansen (2010) on the mid-late Darriwilian (Didymograptus artus-Glyptograptus teretiusculus zones) Elnes Formation of the Oslo region, Norway, recognized two main brachiopod associations in offshore settings, e.g., a lingulid association, dominated by acrotretids and lingulids, found in the dark-grey dysoxic mudstones deposited in offshore bottoms below the storm wave base, and an association consisting of flat-shelled plectambonitoids (Alwynella Spjeldnaes, 1957, andCathrynia Candela, 1999, abundant lingulids (Broeggeria) and indeterminate dalmanelloids that inhabited presumably slightly more oxygenated soft bottoms. Patzkowsky (1995)…”