Precambrian—Cambrian boundary and correlation from southwestern and central part of Spain

1984 ◽  
Vol 121 (3) ◽  
pp. 221-228 ◽  
Author(s):  
E. Liñán ◽  
T. Palacios ◽  
A. Perejón
Keyword(s):  
Iberian Peninsula ◽  
Lower Cambrian ◽  
First Record ◽  
Trace Fossils ◽  
Middle Part ◽  
Early Cambrian ◽  
Upper Proterozoic ◽  
Upper Vendian ◽  
General Series ◽  
Calcareous Microfossils

AbstractThis paper comprises the first palaeontological correlation between the Upper Proterozoic–Lower Cambrian Series of Ossa-Morena, Luso-Oriental-Alcúdica and Galaico-Castellana Zones of the Iberian Peninsula.The authors show the palaeontological events on acritarchs, stromatolites, cyanophyta, soft-bodied metazoa, trilobites, archaeocyathans and skeletal microfossils from three representative sequences of the above mentioned zones and discuss the position of the Precambrian–Cambrian boundary in the sequences. The Sierra de Córdoba general Series (Ossa-Morena Zone) has an erosive discontinuity between the rocks with the first record of Cambrian metazoan activity (Skolithos sp., Monomorphichnus sp., Phycodes pedum and Rusophycus sp.) and the rocks with a palynological association (Bavlinella faveolata, Protosphaeridium flexosum, Trachisphaeridium sp., aff. Octoedryxium truncatum, Phycomicetes? sp. and cf. Ooidium sp.) which suggests a Lower–Middle Vendian age. For this reason we suggest that the Precambrian–Cambrian boundary be placed at this unconformity.The upper part of the Sierra de Guadalupe Series (Luso-Oriental-Alcúdica Zone) includes detrital beds with Phycodes pedum, Planolites sp. and Treptichnus sp. which are also the first record of Cambrian metazoan activity. In the middle part of the sequences, acritarchs attributed to the genus Micrhystridium are found at the top of the Calcareous Beds. This is taken to indicate an early Cambrian age. Vendotaenids and Bavlinella faveolata are found in abundance, thus indicating a Late Vendian age for the middle part of this unit. Thus, we propose the Precambrian–Cambrian boundary be located in the upper part of the Calcareous Beds.In the Rio Uso Series (Galaico-Castellana Zone), the Azorejo Sandstones contain Rusophycus gr. radwanskii, Planolites sp. and Gordia sp. Trace fossils produced by trilobite-like arthropoda (Monomorphichnus) have been cited in the upper part of the underlying Pusa Shales. Moreover, Octoedryxium truncatum and Bavlinella faveolata are found in the lower part of this unit which suggest that the Precambrian–Cambrian boundary could be situated in the Pusa Shales.Calcareous microfossils related to annelid polychaetes are found associated with Upper Vendian acritarchs in the Calcareous Beds of Sierra de Guadalupe. They are the oldest record of skeletal metazoa in the Spanish Series.The medusoids found are associated with a Vendian flora and they are also the oldest non-skeletal metazoa record known in the Iberian Peninsula.

Palynology of uppermost Proterozoic and lowermost Cambrian formations, central Mackenzie Mountains, northwestern Canada

1989 ◽  
Vol 26 (1) ◽  
pp. 129-148 ◽  
Author(s):  
D. Baudet ◽  
J. D. Aitken ◽  
M. Vanguestaine
Keyword(s):  
Rocky Mountains ◽  
Lower Cambrian ◽  
Russian Platform ◽  
Blue Flower ◽  
Flower Formation ◽  
Early Cambrian ◽  
Canadian Rocky Mountains ◽  
Structural Units ◽  
Upper Proterozoic ◽  
Lithostratigraphic Correlation

The acritarch assemblages of strata from the base of the Upper Proterozoic Sheepbed Formation to the base of the Lower Cambrian (Atdabanian) Sekwi Formation are described. The sections sampled are in southwestern (internal) structural units where erosion beneath the "sub-Cambrian"(?) unconformity is least evident. Problems of lithostratigraphic correlation of post-Sheepbed, pre-Backbone Ranges formations remain. Acritarchs indicate the age of the Sheepbed Formation and the Blue-flower Formation above it is latest Proterozoic (Vendian), whereas that of the Vampire Formation is Early Cambrian (Atdabanian). The Backbone Ranges Formation has not yielded datable acritarchs, but it is for the most part Cambrian in age, based on other fossil evidence. Comparisons are made with the Russian Platform and southern Canadian Rocky Mountains successions. The total number of acritarch genera increases markedly across the Precambrian–Cambrian transition.

scholarly journals Glacial erratic boulders from Jutland, Denmark, feature an uppermost lower Cambrian fauna of the Lingulid Sandstone Member of Västergötland, Sweden.

2015 ◽  
Vol 63 ◽  
pp. 59-86
Author(s):  
Thomas Weidner ◽  
Gerd Geyer ◽  
Jan Ove R. Ebbestad ◽  
Volker von Seckendorff
Keyword(s):  
Lower Cambrian ◽  
Source Area ◽  
Trace Fossils ◽  
Middle Part ◽  
Northern Germany

Reinvestigation of glacial erratic boulders from Jutland, Denmark, and from northern Germany, has revealed a moderately diverse fauna with the trilobites Holmiella? sp., Epichalnipsus anartanus, Epichalnipsus sp. A, Epichalnipsus sp. B, and Berabichia erratica, three species of lingulid brachiopods, one hyolith species, and trace fossils comparable to Halopoa imbricata. Comparison with faunas from the Cambrian of Scandinavia strongly suggested a biostratigraphic position equivalent to the uppermost part of the (revised) Holmia kjerulfi–‘Ornamentaspis’ linnarssoni to lowermost Comluella?–Ellipsocephalus lunatus zones sensu Nielsen & Schovsbo (2011), or the lower to middle part of the traditional ‘Ornamentaspis’ linnarssoni Zone, but probably a particular horizon and biofacies not yet discovered in Scandinavia. Considerations of glacial transport regimes and the distribution of comparable rock units, as well as a petrographical analysis of the material from the studied erratic boulders and rocks from outcrops in Sweden, indicate that the boulders were derived from the Lingulid Sandstone Member of the File Haidar Formation and the source area is situated in the vicinity of the present-day outcrops in the Halleberg–Hunneberg area, Västergötland, Sweden.

Early Cambrian Ediacaran-type fossils from California

2000 ◽  
Vol 74 (4) ◽  
pp. 731-740 ◽  
Author(s):  
James W. Hagadorn ◽  
Christopher M. Fedo ◽  
Ben M. Waggoner
Keyword(s):  
United States ◽  
Great Basin ◽  
Lower Cambrian ◽  
Trace Fossils ◽  
Early Cambrian ◽  
Marine Environments ◽  
Southwestern United States ◽  
White Mountains ◽  
Lower Member ◽  
Middle Member

Ediacara-type fossils are rare in the southwestern United States, and Cambrian occurrences of soft-bodied Ediacaran-type fossils are extremely rare. We report both discoidal and frondlike fossils comparable to Ediacaran taxa from the western edge of the Great Basin. We describe one specimen of a discoidal fossil, referred to the form species ?Tirasiana disciformis, from the upper member of the Lower Cambrian Wood Canyon Formation from the Salt Spring Hills, California. Two fragmentary specimens of frond-like soft-bodied fossils are described from the middle member of the Lower Cambrian Poleta Formation in the White Mountains, California, and the upper member of the Wood Canyon Formation in the southern Kelso Mountains, California. On the basis of similarities with fossils from the lower member of the Wood Canyon Formation and from the Spitzkopf Member of the Urusis Formation of Namibia, these specimens are interpreted as cf. Swartpuntia. All fossils were collected from strata containing diagnostic Early Cambrian body and trace fossils, and thus add to previous reports of complex Ediacaran forms in Cambrian marine environments. In this region, Swartpuntia persists through several hundred meters of section, spanning at least two trilobite zones.

On the Late Precambrian–Early Cambrian Hartshill Formation of Warwickshire

1978 ◽  
Vol 115 (1) ◽  
pp. 21-36 ◽  
Author(s):  
M. D. Brasier ◽  
R. A. Hewitt ◽  
C. J. Brasier
Keyword(s):  
Shallow Water ◽  
Lower Cambrian ◽  
Volcanic Rocks ◽  
Trace Fossils ◽  
Early Cambrian ◽  
Late Precambrian

SummaryThe Hartshill Formation (c. 270 m) consists largely of shallow-water feldspathic sandstones and greywackes lying unconformably on Precambrian (Vendian?) volcanic rocks and below shales with the first olenellid trilobites. Five members are recognized. The Park Hill Member is conglomeratic and arkosic near the base, passing up into green-grey megarippled quartzites with some thick shale bands. The Tuttle Hill Member is more shaly and glauconitic with conspicuous bioturbation. The Jee's Member is of distinctly cross-laminated glauconitic, feldspathic greywackes and shales with numerous trace fossils. Conglomerates, shales, sandstones, phosphorites and limestones comprise the Home Farm Member, withadiverse Tommotiantype shelly fauna and stromatolites near the top. Massive arkoses and greywackes of the Woodlands Member yield similar shelly fossils in calcareous beds at the base and top while the overlying Purley Shale yields the first Lower Cambrian trilobites.

scholarly journals Acritarchs from the Buen Formation (Lower Cambrian), North Greenland

1988 ◽  
Vol 137 ◽  
pp. 54-54
Author(s):  
G Vidal ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Trace Fossils ◽  
Early Cambrian ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Siliciclastic Sediments ◽  
North Greenland

Siliciclastic sediments of the Buen Formation of North Greenland yield the earliest Cambrian fossils known from North Greenland, with the exception of cyanobacteria described from dolomites of the underlying Portfjeld Formation (see Peel, this report). The fauna is dominated by olenellid and nevadiid trilobites indicating an Early Cambrian age (Poulsen, 1974; Blaker, this report) but hyolithids, bradoriids, sponges and other fossils also occur. Bergstrom & Peel (this report) described trace fossils from the Buen Formation. Of particular interest is the recent discovery of lightly skeletised arthropods comprising an assemblage similar to that of the Middle Cambrian Burgess shale of Canada (Conway Morris et al., 1987).

Micropaleontology across the Precambrian—Cambrian boundary in Spitsbergen

1987 ◽  
Vol 61 (5) ◽  
pp. 898-926 ◽  
Author(s):  
Andrew H. Knoll ◽  
Keene Swett
Keyword(s):  
Eastern Europe ◽  
Lower Cambrian ◽  
East European Platform ◽  
Trace Fossils ◽  
Early Cambrian ◽  
East Greenland ◽  
East European ◽  
Stratigraphic Subdivision ◽  
Biostratigraphic Correlation ◽  
Early Metazoan

Paleobiological studies of early metazoan evolution are critically dependent on the accurate stratigraphic subdivision and correlation of uppermost Proterozoic and Lower Cambrian sequences. Planktonic microfossils evolved rapidly during this period and are widely distributed and abundant in Vendian and Lower Cambrian rocks; therefore, they provide what is potentially one of the best means of correlating successions of this age. In Ny Friesland, Spitsbergen, tillite-bearing detrital rocks of the uppermost Proterozoic Polarisbreen Group are overlain without apparent unconformity by the Tokammane Formation, a tripartite lithologic sequence consisting of quartzarenites (Blårevbreen Member) overlain by dark shales with subordinate sandstone (Topiggane Member) and dolomites (Ditlovtoppen Member).Salterella, hyoliths, and other invertebrate remains occur in the upper part of the Tokammane succession; trace fossils are found in the Tokammane quartzarenites and shales, as well as in the uppermost few meters of the Polarisbreen sequence. Planktonic microfossils occur throughout the succession. They indicate that the Polarisbreen Group is Vendian in age and that a hiatus corresponding in time to the latest Vendian and (perhaps) earliest Cambrian coincides with the Polarisbreen/Tokammane boundary. Lower Topiggane shale samples contain acritarchs comparable to those found in the sub-HolmiaLontova Beds of Eastern Europe. Upper Topiggane samples contain diverse acritarch assemblages that indicate a lateHolmiaorProtolenusage, suggesting the presence of a second hiatus within the Tokammane Formation. Planktonic microfossils allow biostratigraphic correlation with other sequences both within (East Greenland) and between (East European Platform) paleocontinents. Like those from other areas, diversity trends exhibited by late Proterozoic and Early Cambrian acritarchs from Spitsbergen indicate a major Vendian episode of extinction followed by Early Cambrian rediversification of planktonic microfossils.

RETRACTED—Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

2017 ◽  
pp. 1-7 ◽  
Author(s):  
Natalie I. Schroeder ◽  
John R. Paterson ◽  
Glenn A. Brock
Keyword(s):  
Lower Cambrian ◽  
South Australia ◽  
Dorsal Surface ◽  
First Record ◽  
Trace Fossils ◽  
The Body ◽  
New Taxon ◽  
Stage 4 ◽  
Secondary Bifurcations ◽  
Body Fossil

Abstract Rare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar to Rotadiscus and Pararotadiscus of the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossil-bearing layers of the Konservat-Lagerstätte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs of Pararotadiscus guizhouensis Zhao and Zhu, 1994 from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the ‘preservational trap’ and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

scholarly journals Acritarchs from the Upper Proterozoic and Lower Cambrian of East Greenland

1979 ◽  
Vol 134 ◽  
pp. 1-40
Author(s):  
G Vidal
Keyword(s):  
Lower Cambrian ◽  
Russian Platform ◽  
The State ◽  
Tectonic Deformation ◽  
Early Cambrian ◽  
Thermal Alteration ◽  
Island Formation ◽  
East Greenland ◽  
Upper Proterozoic

Acritarchs are described from rocks of the Upper Proterozoic Eleonore Bay Group and Tillite Group and from the Lower Cambrian Bastion Formation and Ella Island Formation. Twenty-four previously described acritarch taxa have been identified. The state of preservation is variable perhaps depending on variable thermal alteration due to thickness of overburden, tectonic deformation and metamorphism. Palaeoenvironmental aspects of some acritarchs are discussed. The acritarchs of the Ella Island Formation and Upper Bastion Formation indicate a late Early Cambrian age in agreement with the age indicated by shelly faunas. A Vendian age is ascribed to the Tillite Group. The upper part of the Eleonore Bay Group is regarded as Late Riphean. Correlations of these units with Lower Cambrian and Upper Proterozoic sequences in the Russian Platform, Scandinavia and elsewhere are presented.

Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

2018 ◽  
Vol 92 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Natalie I. Schroeder ◽  
John R. Paterson ◽  
Glenn A. Brock
Keyword(s):  
Lower Cambrian ◽  
South Australia ◽  
Dorsal Surface ◽  
First Record ◽  
Trace Fossils ◽  
The Body ◽  
New Taxon ◽  
Stage 4 ◽  
Secondary Bifurcations ◽  
Body Fossil

AbstractRare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar toRotadiscusandPararotadiscusof the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossil-bearing layers of the Konservat-Lagerstätte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs ofPararotadiscus guizhouensis(Zhao and Zhu, 1994) from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the ‘preservational trap’ and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

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