A new lower Cambrian eodiscoid trilobite fauna from Swedish Lapland and its implications for intercontinental correlation

AbstractA lower Cambrian eodiscoid trilobite fauna and an associated holmiid trilobite,Holmiasp., are described from a bioclastic limestone at the top of the Torneträsk Formation in the Luobákti section, south of Lake Torneträsk, northern Sweden. Other associated polymerid trilobites includeOrodes?lapponicaandStrenuaeva inflata. The precise age of the trilobite fauna cannot be determined, but its generic composition and stratigraphical position at the top of the lower Cambrian suggest that it was recovered from theOrnamentaspis?linnarssoniAssemblage Zone. Two species of eodiscoids are present:Neocobboldiaaff.dentataandChelediscus acifer. The latter species is known previously from England and southeastern Newfoundland, and provides a novel link between upper lower Cambrian successions in Baltica and Avalonia.

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Phytoplankton from the Lower Cambrian Læså formation on Bornholm, Denmark: biostratigraphy and palaeoenvironmental constraints

Geological Magazine ◽

10.1017/s0016756800008104 ◽

1992 ◽

Vol 129 (1) ◽

pp. 17-40 ◽

Cited By ~ 19

Author(s):

Małgorzata Moczydłowska ◽

Gonzalo Vidal

Keyword(s):

Lower Cambrian ◽

Radioactive Decay ◽

Depositional Environments ◽

Event Correlation ◽

East European ◽

Depositional Settings ◽

Assemblage Zone ◽

Early Palaeozoic ◽

A Minor ◽

Bodies Of Water

AbstractAcritarchs from the Lower Cambrian Læsså formation on Bornholm, Denmark, are taxonomically diverse. Their state of preservation, including thermal, mechanical and chemical alteration, is discussed. Different states of thermal maturation of acritarchs in shales and phosphorites of the Broens Odde member could be explained in terms of possible irradiation from natural radioactive decay. The microfossils form two age-diagnostic assemblages that allow recognition of the Skiagia ornata–Fimbriaglomerella membranacea and Heliosphaeridium dissimilare–Skiagia ciliosa Assemblage Zones within the Broens Odde member of the Laeså formation. Acritarch-based biostratigraphy indicates that the Lower Cambrian Balka Formation and Læså formation correspond to the Schmidliellus mickwitzi Zone and Holmia kjerulfi Assemblage Zone recognized in Baltoscandia and the East European Platform. Acritarch distribution within three different depositional settings indicates that comparable spectra of morphotypes occurred in different depositional environments. This suggests the absence of facies control. During early Cambrian times palaeoenvironmental barriers in shallow, epicontinental shelf basins constituted a minor obstacle for widespread distribution of acritarch taxa. Formerly proposed early Palaeozoic acritarch provincialism appears insufficiently documented in the fossil record and no evidence could be extracted from the Cambrian record. Following a rapid radiation at the onset of the Phanerozoic, Cambrian phytoplankton populations underwent dispersion following oxygenic and nutrient-rich bodies of water within epicontinental and presumably basinal environments. Lower Cambrian acritarch taxa were largely cosmopolitan and little affected by lithofacies associations. A continuous flow of data is contributing to the emergence of acritarch-based biostratigraphy. Its apparent consistency suggests great usefulness for interregional and detailed event correlation.

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The oldest rocks of the Holy Cross Mountains, Poland – biostratigraphy of the Cambrian Czarna Shale Formation in the vicinity of Kotuszów

Acta Geologica Polonica ◽

10.1515/agp-2016-0013 ◽

2016 ◽

Vol 66 (3) ◽

pp. 267-289 ◽

Cited By ~ 5

Author(s):

Zbigniew Szczepanik ◽

Anna Żylińska

Keyword(s):

Lower Cambrian ◽

Holy Cross Mountains ◽

Assemblage Zone ◽

Shale Formation ◽

Stratigraphic Interval ◽

Cambrian System

AbstractThree lower Cambrian acritarch assemblages recognized in four outcrops in the vicinity of Kotuszów in the southernmost part of the Palaeozoic inlier of the Holy Cross Mountains span a stratigraphic interval from the uppermost part of the Asteridium tornatum-Comasphaeridium velvetum Assemblage Zone to the Skiagia ornata- Fimbriaglomerella membranacea Assemblage Zone (most probably its lower part). According to current views (Moczydłowska and Yin 2012), this interval corresponds to the upper part of the Fortunian and to Stage 2 of the Terreneuvian Series. The strata yielding the oldest assemblage are thus the oldest precisely documented rocks in the Palaeozoic succession of the Holy Cross Mountains, and the oldest Cambrian rocks exposed on the surface in Poland. The current biostratigraphic scheme for the pre-trilobitic part of the Cambrian System in the Holy Cross Mountains should be modified so that it is based on local acritarch interval subzones.

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Biochronology of the autochthonous Lower Cambrian in the Laisvall–Storuman area, Swedish Caledonides

Geological Magazine ◽

10.1017/s0016756801005416 ◽

2001 ◽

Vol 138 (4) ◽

pp. 435-453 ◽

Cited By ~ 20

Author(s):

M. MOCZYDŁOWSKA ◽

S. JENSEN ◽

J. O. R. EBBESTAD ◽

G. E. BUDD ◽

M. MARTÍ-MUS

Keyword(s):

Lower Cambrian ◽

New Records ◽

Northern Sweden ◽

Thrust Front ◽

Scandinavian Caledonides ◽

First Time ◽

Cambrian System

New records of phytoplankton (acritarchs), ichnofossils and olenellid trilobites have been studied from the autochthonous upper Neoproterozoic–Lower Cambrian successions along the Caledonian Thrust Front in the Laisvall–Storuman region of northern Sweden. The fossils are from a newly examined natural outcrop at Bergmyrhobben near Lake Storuman, and from previously described fossiliferous outcrops at Delliknäs and Mt. Assjatj, the Laisvall mine and the Maiva borehole successions in the Laisvall area. Acritarch assemblages are recorded throughout the Grammajukku Formation. They are age-diagnostic for the Skiagia–Fimbriaglomerella acritarch Zone, time-equivalent to the Schmidtiellus mickwitzi trilobite Zone (the lower part of the formation), and the Heliosphaeridium–Skiagia acritarch Zone corresponding to the Holmia kjerulfi trilobite Zone (the upper part of the formation). The acritarch record from the Storuman area documents the presence of strata contemporaneous to the Schmidtiellus mickwitzi Zone for the first time in the Scandinavian Caledonides. This zone was previously only recognized in the platform regions of the Baltica palaeocontinent. The ichnofossils from the upper Såvvovare Formation, including ?Harlaniella, Phycodes, Gyrolithes and Palaeophycus ichnogenera, allowed the base of the Cambrian System to be determined within the Maiva Member and the coeval Kautsky Ore Member in the subsurface successions, and to attribute this part of the formation to the Lower Cambrian Platysolenites antiquissimus faunal Zone of Baltica. The trilobite fauna from the Storuman area, attributed tentatively to Holmia sp., occurs at the lowermost stratigraphic level among olenellids in the Caledonides. The range of this species, estimated from the concurrent acritarch biostratigraphy, is within the Schmidtiellus mickwitzi Zone. The stratigraphic significance of the acritarch assemblages and ichnofossils is analysed and the biochronology of the Grammajukku Formation and the upper Såvvovare Formation is discussed in detail in the context of Lower Cambrian zonation in Baltica.

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