The Vendian–Cambrian Cyclometric Stratigraphic Scale for the Southern and Central Siberian Platform

2021 ◽  
Vol 62 (08) ◽  
pp. 904-913
Author(s):  
N.V. Mel’nikov
Keyword(s):  
Siberian Platform ◽  
Regional Scale ◽  
Oscillatory Motion ◽  
Early Cambrian ◽  
Long Period ◽  
Stratigraphic Division ◽  
Regional Gap ◽  
Geologic Processes ◽  
Sedimentation Processes

Abstract —The general Vendian stratigraphic scale of Siberia, with the uncertain age of the Vendian base ranging from 600 to 630– 640 Ma in most of recent publications, remains worse constrained than the Cambrian scale, in which the boundaries of epochs and stages have been well defined. However, the imperfect classical stratigraphic division has been compensated by data on the cyclicity of the Vendian–Cambrian sedimentary section. The Vendian stratigraphy of the Siberian Platform and the related deposition history with cycles of sedimentation and gaps, as well as the hierarchy of sedimentation processes, can be inferred from the succession of alternating clastic, carbonate, and salt units. The cyclicity of geologic processes and their recurrence are attributed to periodic oscillatory motions of the crust. The ranks of these motions correlate with the cyclicity of sedimentary strata, including regocyclites, nexocyclites, and halcyclites separated by gaps. Each Vendian long-period oscillatory motion begins with a regocyclite and ends with a regional-scale gap. The Cambrian section includes one pre-Mayan regional gap at the end of the early Cambrian long-period cycle. Cambrian regocyclites are composed of carbonate subformations and formations in the lower part and alternating salt and carbonate beds in the upper part.

The oldest sequence of skeletal fossils in the Lower Cambrian of southeastern Newfoundland

1983 ◽  
Vol 20 (4) ◽  
pp. 525-536 ◽  
Author(s):  
Stefan Bengtson ◽  
Terence P. Fletcher
Keyword(s):  
Siberian Platform ◽  
Lower Cambrian ◽  
Short Interval ◽  
Time Span ◽  
Early Cambrian ◽  
Late Precambrian ◽  
Complete Sequences ◽  
Continuous Sedimentation

Sections on the Burin Peninsula in southeastern Newfoundland show a record of continuous sedimentation during the Late Precambrian–Early Cambrian transition. These may be correlated lithologically and biostratigraphically with less complete sequences on the Avalon and Bonavista Peninsulas. Below the oldest known trilobites in southeastern Newfoundland (of the Callavia Zone) two consecutive assemblages of skeletal fossils are recognizable: an Aldanella attleborensis assemblage and the succeeding Coleoloides typicalis assemblage. The shift between the two assemblages takes place within the Bonavista Formation in the Avalon–Bonavista region and in a similar succession of mudstones near St. Lawrence on the Burin Peninsula. The quartzitic Random Formation appears to have been deposited during a short interval within the time span represented by the A. attleborensis assemblage, and there is no conclusive biostratigraphical evidence of any major diachronism of this unit. The A. attleborensis assemblage contains taxa known from the lower part of the Tommotian Stage on the Siberian Platform. It is interpreted to be of Tommotian age, and the subsequent shift to the C. typicalis assemblage is tentatively correlated with the Tommotian–Atdabanian boundary as recognized in Siberia.

Late Precambrian–Early Cambrian stratigraphic and faunal succession of eastern California and the Precambrian–Cambrian boundary

1978 ◽  
Vol 115 (2) ◽  
pp. 121-126 ◽  
Author(s):  
C. A. Nelson
Keyword(s):  
Siberian Platform ◽  
Death Valley ◽  
Early Cambrian ◽  
Late Precambrian ◽  
Faunal Succession

SummaryThe Late Precambrian and Early Cambrian strata in eastern California and Nevada can be divided into 3 facies – the eastern Craton, the White-Inyo, and the Death Valley. These 3 facies supply evidence of 3 trilobite zones – the Fallotaspis, the Nevadella and the Bonnia-Olenellus; the inter-relationships are outlined. Correlations with the Siberian Platform successions are discussed and the Precambrian–Cambrian boundary is tentatively placed within the beds of the upper Reed Dolomite in the White-lnyo Range.

scholarly journals Palaeomagnetism of the Bayan Gol Formation, western Mongolia

1996 ◽  
Vol 133 (4) ◽  
pp. 487-496 ◽  
Author(s):  
D. A. Evans ◽  
A. Yu. Zhuravlev ◽  
C. J. Budney ◽  
J. L. Kirschvink
Keyword(s):  
Pacific Ocean ◽  
Siberian Craton ◽  
Siberian Platform ◽  
Lower Cambrian ◽  
High Coercivity ◽  
Early Cambrian ◽  
Thermal Demagnetization ◽  
Magnetic Components ◽  
Western Mongolia ◽  
Oriented Samples

AbstractOriented samples of the Lower Cambrian Bayan Gol Formation from Salaany Gol, Mongolia, were collected at roughly 5 m stratigraphic intervals for palaeomagnetic analysis. Progressive alternatingfield and thermal demagnetization isolated two magnetic components: a present-field overprint, typically removed by 10 mT fields and ~200°C heating; and a high-coercivity, high-unblocking-temperature (550–600 °C), predominantly single-polarity component that was imparted to the rocks prior to early or middle Palaeozoic deformation. Single-polarity magnetization at Salaany Gol contrasts with results from Lower Cambrian rocks on the Siberian platform, previously considered correlative with the Bayan Gol Formation, which show a prominent change in polarity bias near the top of the Tommotian Stage. Two hypotheses can explain this discrepancy. First, the entire Bayan Gol Formation may correlate with the predominantly reversely polarized, lower half of the Tommotian Stage in Siberia. This model is consistent with plausible interpretations of δ13C profiles for the Zavkhan basin and the Siberian platform. Alternatively, the characteristic magnetic direction from our samples may be a pre-fold overprint. If post-accretionary, then comparison with Siberian palaeomagnetic results suggest a Silurian–Devonian remagnetization age, and existing bioand chemostratigraphic correlations provide the most reliable spatial and temporal links between the Zavkhan basin and the Siberian platform. If the observed magnetic directions are primary or an immediate overprint then they may be used to constrain the early Cambrian palaeogeography of the Zavkhan basin and the Palaeo-Pacific Ocean. Mean inclination of 62 ±4° corresponds to a palaeolatitude of 44 ±5°, several thousand kilometres from the equatorial Siberian craton

scholarly journals Regional scale analysis of the altimetric stream network evolution

2006 ◽  
Vol 7 ◽  
pp. 79-83 ◽  
Author(s):  
T. Ghizzoni ◽  
M. Lomazzi ◽  
G. Roth ◽  
R. Rudari
Keyword(s):  
Mathematical Model ◽  
Carrying Capacity ◽  
Regional Scale ◽  
Network Evolution ◽  
Stream Channels ◽  
Stream Network ◽  
Sedimentation Stability ◽  
Flooding Risk ◽  
Sedimentation Processes

Abstract. Floods result from the limited carrying capacity of stream channels when compared to the discharge peak value. The transit of flood waves - with the associated erosion and sedimentation processes - often modifies local stream geometry. In some cases this results in a reduction of the stream carrying capacity, and consequently in an enhancement of the flooding risk. A mathematical model for the prediction of potential altimetric stream network evolution due to erosion and sedimentation processes is here formalized. It works at the regional scale, identifying the tendency of river segments to sedimentation, stability, or erosion. The model builds on geomorphologic concepts, and derives its parameters from extensive surveys. As a case study, tendencies of rivers pertaining to the Valle d'Aosta region are analyzed. Some validation is provided both at regional and local scales of analysis. Local validation is performed both through a mathematical model able to simulate the temporal evolution of the stream profile, and through comparison of the prediction with ante and post-event river surveys, where available. Overall results are strongly encouraging. Possible use of the information derived from the model in the context of flood and landslide hazard mitigation is briefly discussed.

Features of paleohydrogeochemistry of the lower cambrian deposits of the Siberian Platform

2020 ◽  
Author(s):  
Anatoly V. Chernykh ◽  
◽  
Dmitry A. Tokarev ◽  
Dmitry A. Novikov ◽  
Fedor F. Dultsev ◽  
...  
Keyword(s):  
Calcium Chloride ◽  
Siberian Platform ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
Potassium Salts ◽  
Modern Chemistry ◽  
Host Rocks

The results of paleohydrogeochemical reconstructions of the Lower Cambrian deposits of the Siberian platform are presented. The characteristic of the main biota groups of the Early Cambrian time of the Siberian paleobasin is given. The conditions of formation and compositional features of syngenetic waters are considered. The modern chemistry of the inter–salt brines is mainly of an inherited nature, while the appearance of super–strong brines of calcium chloride composition is due to the processes of deep interaction of the initial sea brine with the host rocks. Based on the analysis of the hydrogeochemical features of the Lower Cambrian sediments, the prediction of the zones of distribution of potassium salts is given.

Earliest skeletal fossils from Precambrian–Cambrian boundary strata, Elburz Mountains, Iran

1989 ◽  
Vol 126 (3) ◽  
pp. 283-289 ◽  
Author(s):  
B. Hamdi ◽  
M. D. Brasier ◽  
Jiang Zhiwen
Keyword(s):  
Central Asia ◽  
South China ◽  
Siberian Platform ◽  
Early Cambrian ◽  
Late Precambrian

AbstractThe lithological and biotic succession across the late Precambrian to early Cambrian interval is outlined for the Dalir and Valiabad successions of the Elburz Mountains of Iran. The Lower Dolomite Member contains an assemblage of phosphatic tubes and other poorly preserved remains. The succeeding Lower Shale Member bears macroscopic chuariamorphid algae. Early skeletal fossil diversity rises through the Middle Dolomite Member, with the successive appearance ofProtohertzina anabarica, Cambrotubulus decurvatusandAnabarites trisulcatus, culminating near the top of the dolomites with the appearance ofPurellasp.,Maikhanella multa, Tiksitheca licisand circothecids. This succession is compared with lower to upper parts of the Nemakit-Daldyn Formation of Siberia. The overlying Upper Shale Member bears phosphatic beds at its base with allathecids and an uncoiled pelagiellid (?Aldanellasp.) that suggest comparison with lower Tommotian strata and the Precambrian–Cambrian boundary phosphorite event of southern and central Asia. A rich assemblage of molluscs appears high in the Upper Shale Member, including theLatouchella korobkovigroup and thePelagiella lorenzigroup. The succession is broadly homotaxial with those from the Siberian Platform and Mongolia and those platforms bordering Gondwana (India, Kazakhstan, South China).

Evolution of archaeocyaths and palaeobiogeography of the Early Cambrian

1986 ◽  
Vol 123 (4) ◽  
pp. 377-385 ◽  
Author(s):  
Andrey Yu. Zhuravlev
Keyword(s):  
North America ◽  
North Africa ◽  
Siberian Platform ◽  
Western Europe ◽  
Early Cambrian ◽  
Western North America ◽  
Geographic Isolation ◽  
Taxonomic Rank ◽  
Two Peaks

AbstractIn the Early Cambrian, there were two peaks of the increase in number of new archaeocyathan genera. These diversification bursts are, perhaps, related to significant changes in Early Cambrian palaeogeography. The first burst at the beginning of the Atdabanian was, perhaps, connected with the initiation of archaeocyathan expansion beyond the Siberian Platform. During the second half of the Atdabanian, closely related archaeocyathan assemblages were established from North Africa to Australia because neither climate, nor geographic isolation could have affected their differentiation in that time. At the end of the Atdabanian and the beginning of the Botomian the number of archaeocyathan genera again increased sharply, and isolated provinces were established. The American–Koryakiyan province was formed in western North America (from Alaska to Sonora) and included the Koryakiya, while the Afro–Siberian–Antarctic province probably extended from North Africa and Western Europe to Siberia, Australia, and Antarctica. The main difference between the regular archaeocyathan assemblages lies in what skeletal elements filled the intervallum. There was a certain stability in the distribution of skeletal elements of high taxonomic rank and an interchangeability of elements of low taxonomic rank.

Magnetostratigraphy of lower Cambrian strata from the Siberian Platform: a palaeomagnetic pole and a preliminary polarity time-scale

1984 ◽  
Vol 121 (3) ◽  
pp. 189-203 ◽  
Author(s):  
Joseph L. Kirschvink ◽  
A. Yu. Rozanov
Keyword(s):  
Siberian Platform ◽  
Time Scale ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
Polar Wander ◽  
Lena River ◽  
Apparent Polar Wander Path ◽  
Geographical Position ◽  
Geomagnetic Polarity ◽  
Geomagnetic Polarity Time Scale

AbstractFour sedimentary sections seen in continuous exposures along the Lena River on the Siberian Platform in Yakutia contain a record of the geomagnetic field during the Tommotian and Atdabanian stages of Early Cambrian time. The direction of the stable remanent magnetization indicates that the Siberian platform was located on the equator, and the corresponding palaeomagnetic pole provides a well-dated extension of the Siberian apparent polar wander path. A belt of archaeocyathid bioherms which separates two major facies zones in the lower Cambrian was positioned on and aligned more or less parallel with the palaeoequator. The geographical position of this belt appears to have tracked the southward motion of the Siberian platform during post-Tommotian time. These palaeomagnetic results combined with the extensive biostratigraphy of the Siberian Platform provide a provisional geomagnetic polarity time scale for this part of Early Cambrian time. Comparison of these results with data of similar age from Central Australia suggests that strata of Tommotian and lower Atdabanian age are not present in the Amadeus Basin of Australia.

Shelly fossils from the Early Cambrian (Toyonian) Wirrealpa, Aroona Creek, and Ramsay Limestones of South Australia

1993 ◽  
Vol 67 (5) ◽  
pp. 758-787 ◽  
Author(s):  
Glenn A. Brock ◽  
Barry J. Cooper
Keyword(s):  
Sequence Stratigraphy ◽  
Siberian Platform ◽  
South Australia ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Marine Transgression ◽  
Small Shelly Fossils ◽  
Flinders Ranges ◽  
Yorke Peninsula

Small shelly fossils from the Wirrealpa and Aroona Creek Limestones, Flinders Ranges, and the temporally equivalent Ramsay Limestone, Yorke Peninsula, South Australia, are described and assessed. These formations, deposited during a widespread marine transgression, have traditionally been assigned an early Middle Cambrian age based on lateral facies relationships, lithostratigraphic interpretation, and age diagnostic trilobites. However, new data from regional sequence stratigraphy and mounting paleontological evidence suggest that a late Early Cambrian age (equivalent to the Toyonian Stage from the Siberian Platform) is more appropriate for these units. Twenty-four taxa, including a number of problematica, poriferans, coeloscleritophorans, palaeoscolecidans, “conodontomorphs,” hyolithelminthes, hyoliths, mollusks, and inarticulate brachiopods, are reported herein; many of these have not previously been reported from the Cambrian of South Australia. The enigmatic Chalasiocranos exquisitum n. gen. and sp., known from disarticulated tuberculate cone-shaped phosphatic sclerites, and Protomelission gatehousei n. gen. and sp., a problematic, perhaps colonial organism, known from phosphatic plates, are especially notable. The genus Kaimenella is formally included in the Palaeoscolecida, and two species (including K. dailyi n. sp.) are recognized.

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