The late Sandbian – earliest Katian (Ordovician) brachiopod immigration and its influence on the brachiopod fauna in the Oslo Region, Norway (original) (raw)
Related papers
2006
The aim of the present study is to improve knowledge of the brachiopod fauna in the lower part of the Arnestad Formation (Caradoc) in the OsloAsker district and to document faunal changes prior to the Scoto-Appalachian brachiopod migration into the Oslo Region. This migration appears to have taken place during deposition of the upper Haljala and Keila stages (Lower Caradoc). Like the faunas in other parts of Baltica, the brachiopod fauna in the lower part of the Arnestad Formation, occupied an environment influenced by moderate current or wave regimes. It has a lower diversity than the more cosmopolitan brachiopod fauna in the upper part of the formation. The fauna in the lower part of the Arnestad Formation is, however, more diverse than the equivalent Swedish faunas in the Scanian Confacies Belt (“Outer facies belt”). The closest affinity, at the generic level, is with the faunas from the Livonian Tongue of the Central Baltoscandian Confacies Belt (“Middle facies belt”). The Onnie...
Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods
Geobios, 2008
Bed-by-bed sampling of brachiopods from selected Kundan Stage localities in the East Baltic has permitted the construction of a-diversity curves, unprecedented in detail from this particular stage and region. These a-diversity curves can be correlated between the investigated sections, along an east to west transect of some 200 km and indicate bioevents associated with intervals of increased palaeo-water depth. The highest peaks in a-diversity occur when biofacies analysis and sedimentological evidence indicate drowning events. The events involve mainly taxa endemic to the Baltic province at this time and thus, the radiation proceeded by a modest expansion of the brachiopod fauna into deeper-water environments, isolated at this time from major immigrations. In addition to increased a-diversity, b-diversity was signalled by new, deeper-water communities and the isolation of the province helped retain high values of g-diversity. # 2008 Elsevier Masson SAS. All rights reserved. Résumé L'échantillonnage niveau par niveau de brachiopodes dans une sélection de localités de l'Étage de Kundan dans l'Est de la Baltique a permis d'établir des courbes de diversité de niveau a d'une précision inégalée pour cet Étage et cette région. Ces courbes de diversité de niveau a peuvent être corrélées entre les différentes coupes étudiées selon un axe est-ouest sur une distance d'environ 200 km. Elles mettent alors en évidence des bio-événements associés à des intervalles de temps durant lesquels on observe une augmentation de la paléoprofondeur. Les pics de diversité maximum au niveau a sont liés à des approfondissements du milieu, démontrés par des analyses sédimentologiques et des biofaciès. Ces évènements concernent essentiellement des taxons endémiques à la province baltique à cette époque. On observe une modeste expansion des faunes de brachiopodes dans les environnements plus profonds, isolés à cette époque de toute immigration importante. En plus d'une augmentation de la diversité de niveau a, la diversité de niveau b se signale par de nouvelles communautés d'eau profonde et l'isolement de la province a permis de garder une importante diversité de niveau g.
Brachiopod associations from the Middle Ordovician of the Oslo Region, Norway
Palaeontology, 2010
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 Spjeldnæs 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.
Bulletin of the Geological Society of Denmark
Analyses of the distribution, in time and space, of approximately 300 Ordovician rhynchonelliformean brachiopods in the East Baltic allow the development of a faunal template for the Baltic Province (sensu stricto) within the context of the European Realm. Two different brachiopod magnafacies, the upper and lower ramp associations, are monitored through time. Changes in the brachiopod fauna through uppermost Hunneberg to the Porkuni stages are demonstrated from different drill core sections and some bedrock exposures located in facially contrasting areas across the region. The main developmental trends within the brachiopod biofacies of the shallower part of the palaeobasin (North Estonian facies belt) are characterized by relatively continuous changes in taxonomic composition including the evolution of endemics and the establishment of relatively persistent associations, especially during the later Ordovician. In the deeper parts of the palaeobasin (Central Baltoscandian confacies ...
Geological Magazine, 2009
A detailed ecostratigraphical framework is established for the lower Middle Ordovician Kundan regional stage of the East Baltic area corresponding to the Asaphus expansus, A. raniceps and A. eichwaldi trilobite zones (lower Darriwilian). The study is based on approximately 6200 brachiopods collected bed by bed from limestone sections in northern Estonia (Harku Trench and Saka) and western Russia (Putilovo Quarry, Lava River canyon and Lynna River valley) with, in addition, the first detailed systematic assessment of the Kundan brachiopods of the East Baltic. These sections represent an oblique depth transect some 400 kilometres long, deepening eastwards. Five biofacies associations have been recognized using detrended correspondence and cluster analyses: a shallow-water Lycophoria association, a transitional Gonambonites association and two deeper-water associations, the soft-substrate Orthis callactis and the hard-substrate Orthambonites associations. A separate, fifth soft-substra...
Orthacean and strophomenid brachiopods from the Lower Silurian of the central Oslo Region
Lethaia, 1995
Fossils and Strata is an international series of monographs and memoirs in palaeontology and stratigraphy, published in cooperation between the Scandinavian countries.1t is issued in Numbers with individual pagination. Fossils and Strata forms part of the same structured publishing programme as the journals Lethaia and Boreas. These two journals are fully international and accept papers within their respective sectors of science without national limitations orpreferences. Fossils and Strata, however, is an outlet for more comprehensive systematic and regional monographs emanating primarily from the five countries of Norden. Contributions from other countries may also be included if this series is deemed appropriate with regard to distribution and availability. Articles can normally only be accepted if they are heavily subsidized by the national Research Council in their country of origin or by other funds. All in come is reinvested in forthcoming numbers of the series. Although articles in German and French may be accepted, the use of English is strongly preferred. An English abstract should always be provided, and non-English articles should have English versions of the figure captions. Abstracts or summaries in one or more additional languages may be added. Many regional or systematic descriptions and revisions contain a nucleus of resuIts which are of immediate and general interest in international palaeontology and stratigraphy. It is expected that authors of such papers will to some extent duplicate their publication in the form of an article for a journal, in the first place Lethaia or Boreas.