Three new Upper Cambrian stages for North America

Ludvigsen, Rolf; Westrop, Stephen R.

doi:10.1130/0091-7613(1985)13<139:tnucsf>2.0.co;2

Cited by 93 publications

(46 citation statements)

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“…This was followed by major regression and a widespread hiatus between the Dresbachian and Franconian Stages (i.e the Steptoean Stage of Ludvigsen & Westrop 1985, spanning the Aphelaspis to lower Elvinia Zones). This break can be traced across a wide area, as follows: in the eastern part of the Great Basin, in the Rocky Mountains from Montana to Arizona, in the mountains of northwestern and southwestern Canada, in the midcontinent region of Texas, Missouri and the upper Mississippi Valley, in western Newfoundland and in northwestern Greenland (Palmer 1981b;Westrop 1986).…”

Section: Cambrian Of the Great Basinmentioning

confidence: 99%

Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession

Brasier

1993

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Section: Cambrian Of the Great Basinmentioning

confidence: 99%

Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession

Brasier

1993

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“…4). The fauna includes cosmopolitan genera that Taylor and Rushton (1971) equated with the Dresbachian and lowest Franconian stages of North America; stages that equate with the Marjuman and Steptoean of Ludvigsen and Westrop (1985). …”

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confidence: 99%

The Furongian (late Cambrian) Steptoean Positive Carbon Isotope Excursion (SPICE) in Avalonia

Woods

Wilby

Leng

et al. 2011

JGS

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The Steptoean Positive Carbon Isotope Excursion (SPICE) of earliest late Cambrian (Furongian) age is identified in England. The excursion is found within a ca 145 m thick siliciclastic succession within the middle and higher part of the Outwoods Shale Formation of Warwickshire, and reaches a maximum δ 13 C org amplitude of 4.1‰ at values of -25.6‰. Biostratigraphical data show that the excursion occupies the greater part of the Olenus trilobite biozone, an equivalent of the Glyptagnostus reticulatus biozone that marks the base of the Furongian and coeval base of the Steptoean in North America. The amplitude of the excursion approaches that recorded in limestonedominated Laurentian successions, and is greater than that recently documented for organic-rich mudstones of palaeocontinental Baltica in southern Sweden. A minor positive excursion above the SPICE may equate with a similar excursion recognised in Siberia. The SPICE in the Outwoods Shale Formation seems closely linked to the widely recognised early Furongian eustatic sea level rise. There is no evidence in the English succession for slightly later regression, elsewhere considered coincident with the peak of the excursion and pivotal to some previous models explaining the SPICE.Keywords: Cambrian, Furongian, carbon isotope excursion, England, Avalonia Late Cambrian (Furongian) carbonate successions in many parts of the world (North America, Argentina, Siberia, Kazakhstan, China, Australia) contain an interval of markedly positive δ 13 C carb values, peaking at +5‰ (Saltzman et al., 2000;Kouchinsky et al., 2008). More recently, the same positive Carbon Isotope Excursion (CIE) has been identified in organic-rich mudstones of the Alum Shale Formation in southern Sweden, where δ 13 C org peak values are around -28‰ (with a maximum amplitude of around 2‰) (Ahlberg et al., 2009). This CIE, first recognised in the late Cambrian of North America by Brasier (1993) and confirmed as a global CIE by Saltzman et al. (1995), is termed the Steptoean Positive Carbon Isotope Excursion (SPICE) (Saltzman et al., 1998). We report here the occurrence of the SPICE in the Cambrian of central England, the first record in an Avalonian succession. The palaeogeographic setting of these mid-shelf clastic deposits contrasts with 1 areas where the SPICE has previously been identified (e.g. shallow carbonate shelf in North America; shallow, dysoxic-anoxic shelf in southern Sweden). This contrasting setting provides an opportunity to critically assess the likely driving mechanism(s) that created this global isotopic excursion.The SPICE is believed to have had a duration of about 4 Ma (Saltzman et al., 1998), although 3 Ma is probably a better estimate based on dates recently published by Peng and Babcock (2008). In common with other positive CIEs in the geological record, one interpretation of the SPICE is attributed to increased burial of organic carbon, that is enriched in isotopically light 12 C thus increasing the 13 C pool in the oceans. However, terrestrial weathering impacts relate...

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“…This places the sample at the top of the Upper Shale Member above the Crepicephalus-Aphelaspis biozone boundary. The range of Auritusphaera gen. nov., based on these three samples, appears to be within the three biozones, Cedaria-Crepicephalus-Aphelaspis, straddling the Marjuman-Steptoean Stage boundary of the Upper Cambrian (Ludvigsen and Westrop, 1985). The depositional setting of the Nolichucky Shale has long been considered to be marine, although the presence of peritidal elements in lateral extensions of the middle Bradley Creek Member indicate that the water depth was shallow (Markello and Read ,1981).…”

Section: Geologic Setingmentioning

confidence: 99%

“…Its range begins in the CedariaCrepicephalus biozone, and extends into the Aphelaspis biozone (Glumac and Walker, 2000). This taxon is a potential marker for the Marjuman-Steptoean Stage boundary (sensu Ludvigsen and Westrop, 1985) in the Upper Cambrian.…”

Section: Introductionmentioning

confidence: 99%

A new Cambrian acritarch from the Nolichucky Shale, Eastern Tennessee, U.S.A.

Strother¹

2008

Palynology

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A new acanthomorph acritarch genus, Auritusphaera, is erected to accommodate a distinctive form whose processes form a pseudoreticulum on the surface of a spherical vesicle. The genus is present in, and restricted to, the Upper Shale Member of the Nolichucky Shale in eastern Tennessee, U.S.A., where it is found in two cores drilled in the grounds of the Oak Ridge National Laboratory. The Upper Shale Member corresponds to the upper part of the Cedaria-Crepicephalus biozone and the lower part of the Aphelaspis biozone, and is Late Cambrian in age. The distinctive morphology of this acritarch may render it a potential marker for the Upper Cambrian Marjuman/Steptoean Stage boundary.

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Three new Upper Cambrian stages for North America

Cited by 93 publications

References 0 publications

Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession

Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession

The Furongian (late Cambrian) Steptoean Positive Carbon Isotope Excursion (SPICE) in Avalonia

A new Cambrian acritarch from the Nolichucky Shale, Eastern Tennessee, U.S.A.

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