Lithostratigraphy and sedimentology of a Lower Ordovician limestone sequence at Hälludden, Öland, Sweden

Nordlund, Ulf

doi:10.1080/11035898909454760

Cited by 22 publications

(17 citation statements)

References 44 publications

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“…The section has been intensively studied since the 1940s (Bohlin ) and numerous publications report the faunal content, the sedimentological features and stratigraphical details (see e.g. Jaanusson & Mutvei ; Nordlund ; Stouge ; Kröger ). The conodont fauna indicates a Darriwilian age for the entire Hälludden section (Stouge , p. 104; Stouge personal communication 2012).…”

Section: Localities and Cephalopod Faunasmentioning

confidence: 99%

“…Chen & Lindström (), based on cephalopod septal strength measurements, interpreted the 0.5 m below D as a shallowing, the 0.3 m above D as a pronounced deepening with depths of up to 200 m. This is contrary to earlier interpretations by Nordlund (). Nordlund () analysed the sediment components and interpreted them as evidence for a subsequent shallowing from the ooid horizon upward (see discussion below).…”

Section: Localities and Cephalopod Faunasmentioning

confidence: 99%

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Middle Ordovician cephalopod biofacies and palaeoenvironments of Baltoscandia

Kröger

Rasmussen

2014

LET

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During the Middle Ordovician cephalopods became an important part of the macrofauna of the Baltoscandian carbonate platform. The earliest cephalopod abundance peak was reached during the early Darriwilian, within the Kunda Stage Yangtzeplacognathus crassus and Lenodus pseudoplanus conodont zones. In sediments of this time interval large orthoconic cephalopods often occur in masses with more than one specimen per square‐meter on bedding surfaces. The assemblages are characterized by the strong dominance of often large endocerids. In proximal depositional settings coiled tarphycerids and other cephalopod groups are an important additional component. In the most distal settings orthocerids are the most important secondary component. Correspondence Analysis of assemblages throughout Baltoscandia revealed three distinct biofacies, which here are termed Orthocerid, Proterovaginoceras and Anthoceras Biofacies, respectively. The biofacies reflect differences in depth and proximity to the shoreline and are consistent with the Baltoscandian Confacies Belts. Spatial changes in absolute abundance and taxonomic composition indicate increased original cephalopod population densities and habitat expansion within the Y. crassus and L. pseudoplanus conodont zones. A nearly coeval abundance peak in a similar facies in South China indicates supraregional causes of the mass occurrence, probably reflecting a globally increased nutrient availability in the water column during the Darriwilian.

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Section: Localities and Cephalopod Faunasmentioning

confidence: 99%

Section: Localities and Cephalopod Faunasmentioning

confidence: 99%

Middle Ordovician cephalopod biofacies and palaeoenvironments of Baltoscandia

Kröger

Rasmussen

2014

LET

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“…Sturesson ), but their characteristics and genetic origin likely differ (cf. Hessland ; Nordlund ). Their occurrence may, however, be connected to the oncoids documented herein.…”

Section: Discussionmentioning

confidence: 99%

“…). Coeval facies changes and stratigraphical gaps in other parts of Baltoscandia also indicate a sea‐level fall (Nordlund ,b; Chen & Lindström ; Dronov et al . ; Saadre et al .…”

Section: Geological Settingmentioning

confidence: 99%

“…Chen & Lindström () concluded that the epeiric sea was generally 200–300 m deep over most of Sweden, reaching a minimum of c. 100 m depth at Hälludden, Öland, during the most extensive shallowing recorded in the studied strata. In contrast, based on detailed sedimentological studies, Nordlund (,b) noted the possibility of sub‐aerial conditions during the shallowest part of the same stratigraphical sequence at Hälludden. The lowstand in question correlates roughly to the lower third part of the Holen Limestone.…”

Section: Geological Settingmentioning

confidence: 99%

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Palaeoenvironmental significance of cool-water microbialites in the Darriwilian (Middle Ordovician) of Sweden

Lindskog

2014

LET

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Well‐developed oncoids and centimetre‐sized stromatolites are reported for the first time from the Darriwilian (Middle Ordovician) cool‐water ‘orthoceratite limestone’ at Kinnekulle, Västergötland, Sweden. The characteristics and stratigraphical distribution of these microbialites show an apparent relationship to fluctuations in relative sea level. The most abundant and well‐developed oncoids occur in stratigraphical intervals that are characterized by notable sea‐level lowstands. Stromatolites, which share many compositional characteristics with the oncoids, are essentially confined to a single bed associated with an especially prominent lowstand. Stromatolite‐like lamination also occurs in the uppermost part of the studied succession, but this feature may be of abiogenic origin. The microbialites appear to be originally calcareous, but synsedimentary iron‐ and/or phosphate‐enriched laminae are conspicuous, and secondary substitution by coarse calcite and barite is common. Iron staining is most prominent in poorly preserved specimens. Diagenesis has occluded the identity of the producers of these microbialites, but characteristics of associated endolithic borings suggest that they were formed in photic waters. The laminated fabrics of the documented microbialites record a depositional environment sensitive to high‐frequency environmental change. Most significantly, the microbialites have provided important information about the depositional environment of their enigmatic host limestone, and the collective observations challenge the notion that the studied strata were deposited in a deep shelf to basinal environment – rather, it appears that they are to a large extent, shallow‐water deposits, formed in waters only a few tens of metres deep.

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Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods

Rasmussen¹,

Harper²

2008

Geobios

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Lithostratigraphy and sedimentology of a Lower Ordovician limestone sequence at Hälludden, Öland, Sweden

Cited by 22 publications

References 44 publications

Middle Ordovician cephalopod biofacies and palaeoenvironments of Baltoscandia

Middle Ordovician cephalopod biofacies and palaeoenvironments of Baltoscandia

Palaeoenvironmental significance of cool-water microbialites in the Darriwilian (Middle Ordovician) of Sweden

Resolving early Mid-Ordovician (Kundan) bioevents in the East Baltic based on brachiopods

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