The Cambrian Period

Shanchi, Peng; Babcock, Loren E.; Ahlberg, Per

doi:10.1016/b978-0-12-824360-2.00019-x

Cited by 68 publications

(42 citation statements)

References 238 publications

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“…2B); retrospectively, at least three carbon isotope excursions, which probably represent the Cambrian arthropod radiation isotope excursion (CARE), Mingxinsi carbon isotope excursion (MICE), and D r a f t 7 archaeocyathan extinction isotope excursion (AECE), are identifiable in the Sekwi Formation (Fig. 2A;Geyer, 2019;Peng et al, 2020;Cramer and Jarvis, 2020). The redlichiid-olenellid extinction isotope excursion (ROECE) may be partly expressed in Section 4 of Dilliard et al (2007), which, unlike the type section (section 10), has an intact upper contact that is not compromised by faulting or post-Sekwi exposure in the vicinity of the Mackenzie-Redstone arch [Dilliard et al 2007 (fig.…”

Section: Biostratigraphymentioning

confidence: 99%

“…The current regional lower Cambrian trilobite biostratigraphic scheme for Laurentia consists of the Fritzaspis, Fallotaspis, Nevadella, and Bonnia-Olenellus zones (Fritz, 1972;Hollingsworth, 2007). These biozones are defined by trilobite genera and span Cambrian stages 3 and 4, comprising what was traditionally known as the trilobite-bearing lower Cambrian (e.g., Peng et al 2020;Geyer 2019). Although the modern lower Cambrian trilobite biozones of Laurentia have been widely used for decades, there are issues with their utility.…”

Section: Lower Cambrian (Stages 3 and 4) Biostratigraphy Of Laurentiamentioning

confidence: 99%

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Biostratigraphic evidence for incremental tectonic development of early Cambrian deep-water environments in the Misty Creek embayment (Selwyn basin, Northwest Territories, Canada)

et al. 2022

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The early evolution of the Misty Creek embayment (MCE), a prominent, northwest-trending sub-basin of the economically important Selwyn basin, is poorly understood. The abrupt contact between Cambrian Stage 4 (traditional lower Cambrian) carbonate ramp strata of the Sekwi Formation and overlying Miaolingian (traditional middle Cambrian) deep-water, calciturbiditic strata of the Hess River Formation has been regarded as diachronous. This important transition, which marks the onset of long-lived, deep-water conditions in the MCE, remains unexplained. This study uses biostratigraphic data from a previously undescribed location in the MCE, existing biostratigraphic and lithostratigraphic data from the 1970s, and regional thickness patterns to characterise the sharp yet diachronous transition from lithofacies typical of the Sekwi Formation to those typical of the Hess River Formation. The dramatic change in depositional environments was diachronous yet non-gradational, precluding a eustatic cause. The change was geologically abrupt, probably through two extension-related subsidence events, with different geographic extents, which heralded the MCE’s long life as a deep-water basin. The onset of deep-water conditions in the MCE occurred semi-contemporaneously with other extension-related events that are recorded in the northern Canadian Cordillera, demonstrating that Cambrian Series 2 – Miaolingian was a time of widespread extension and subsidence along the western margin of Laurentia.

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Section: Biostratigraphymentioning

confidence: 99%

Section: Lower Cambrian (Stages 3 and 4) Biostratigraphy Of Laurentiamentioning

confidence: 99%

Biostratigraphic evidence for incremental tectonic development of early Cambrian deep-water environments in the Misty Creek embayment (Selwyn basin, Northwest Territories, Canada)

et al. 2022

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“…Approximately 300 m above the base of the Middle Member, archaeocyathid reefs and hash can be observed in bioturbation-free zones (Fig. 4F), constraining the strata to a window of the early Cambrian between the Tommotian and Toyonian Stages (~525-511 Ma, or mid-Terreneuvian Age 2 to Cambrian Series 2, Age 4; Peng et al, 2020). The Middle Member of the Erkhelnuur Formation ranges from 600-800 m thick, and is best exposed in sections EA1801-1802 (see Fig.…”

Section: Middle Membermentioning

confidence: 99%

Stratigraphy of the Khuvsgul Group, Mongolia

2021

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The Khuvsgul Group (Khuvsgul Province, Mongolia) is a Late Neoproterozoic to Cambrian carbonate-dominated succession that includes minor glacial diamictite and one of the largest known ore-grade phosphate deposits in the world. These strata, which have experienced low-grade metamorphism, are exposed in the Khoridol-Saridag Range on the western margin of Lake Khuvsgul. Since 2017, new geologic mapping and field studies have been conducted in the Khuvsgul region. During the course of this work, it has become necessary to restructure the stratigraphic framework of the Khuvsgul Group in order to better facilitate geologic mapping, stratigraphic observations, and regional correlations. We have divided the lower Khuvsgul Group into four distinct formations spanning the Cryogenian and Ediacaran, each of which encompass strata associated with the Sturtian glaciation, Cryogenian non-glacial interlude, Marinoan glaciation, and basal Ediacaran transgression respectively. The phosphorites of the Khuvsgul Group are now included within a new distinct formation, while the overlying Cambrian carbonates and siliciclastic rocks have been further subdivided to streamline mapping and correlation efforts. The stratigraphic framework outlined below will simplify identification and differentiation of Khuvsgul Group rocks in the field and provide a foundation for the interpretation of Khuvsgul Group strata within the context of the changing climatic, tectonic, and paleoenvironmental conditions of the late Neoproterozoic and early Cambrian.

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“…This is especially true in shale deposits (e.g., Hollingsworth, 2005;McCollum and McCollum, 2011;Webster, 2011a, b, c, d;Webster et al, 2011), but less so in carbonates in which pagetiids, ptychoparioids and corynexochines can be locally abundant (e.g., Fritz, 1972;Hopkins and Webster, 2009;Geyer and Peel, 2011;Webster, 2011a, e). Whereas the endemic olenelline trilobites have become the major focus for biostratigraphic correlation of Series 2 strata in Laurentia, corynexochines-especially the oryctocephalids-have the potential to allow international correlations (e.g., Sundberg and McCollum, 1997;Sundberg et al, 1999Sundberg et al, , 2016Fletcher, 2001Fletcher, , 2003Fletcher, , 2007Zhao et al, 2001;Geyer and Peel, 2011;Lin et al, 2019;Peng et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Corynexochine trilobites of the Harkless Formation and Mule Spring Limestone (Cambrian Series 2, Stage 4), Clayton Ridge, Nevada

Sundberg

Webster

2021

J. Paleontol.

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Most Cambrian Series 2 faunas of Laurentia are dominated by olenelline trilobites; however, non-olenelline trilobites occur with the olenellines and sometimes dominate the assemblages. Reported here are such non-olenelline trilobites from the Harkless Formation and Mule Spring Limestone at Clayton Ridge, Nevada. At the bottom of the Saline Valley Tongue, Harkless Formation, are two assemblages that are characterized by corynexochines and/or ptychoparioids, with olenellines occurring as only rare components. The corynexochines present in these assemblages include Bonnia cf. B. brennus (Walcott, 1916), Ovatoryctocara cf. O. yaxiensis Yuan et al., 2009, Protoryctocephalus? aff. P.? arcticus Geyer and Peel, 2011, Ogygopsis sp. indet., and Oryctocephalops frischenfeldi Lermontova, 1940. These assemblages are from the mid-Dyeran Stage, below the lowermost zone in the upper Dyeran (Arcuolenellus arcuatus Biozone), and can be correlated to Series 2 Stage 4 (Cambrian) assemblages in Greenland, Siberia, and South China based on the corynexochines. Also in the Saline Valley Tongue and the overlying Mule Spring Limestone and lowermost Emigrant Formation are olenelloid-dominated assemblages that contain the corynexochines Bonnia columbensis Resser, 1936, Zacanthopsis aff. Z. levis (Walcott, 1886), and Z. sp. indet.

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The Cambrian Period

Cited by 68 publications

References 238 publications

Biostratigraphic evidence for incremental tectonic development of early Cambrian deep-water environments in the Misty Creek embayment (Selwyn basin, Northwest Territories, Canada)

Biostratigraphic evidence for incremental tectonic development of early Cambrian deep-water environments in the Misty Creek embayment (Selwyn basin, Northwest Territories, Canada)

Stratigraphy of the Khuvsgul Group, Mongolia

Corynexochine trilobites of the Harkless Formation and Mule Spring Limestone (Cambrian Series 2, Stage 4), Clayton Ridge, Nevada

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