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Articoli di riviste sul tema "Stratigraphic Cambrian"

1

Fortey, Richard A. "Trilobite Evolution and Systematics". Short Courses in Paleontology 3 (1990): 44–65. http://dx.doi.org/10.1017/s2475263000001732.

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Trilobites are the most diverse of extinct arthropod groups, being known from several thousand genera; many more are discovered each year. They range in age from near the base of the shell-bearing Cambrian to high in the Permian. Because many trilobites evolved quickly, they have been widely employed in stratigraphy; in the Cambrian they are possibly the most important stratigraphical fossils. This has been a mixed blessing because some experts studying the group have tended to place stratigraphical utility foremost in their taxonomic methods. Stratigraphical boundaries have become taxonomic boundaries. This might not matter for stratigraphy, but it does matter for the other kinds of paleobiological studies which have recently become the center of attention. How, for example, can one study extinction, unless the groups extinguished are natural, monophyletic groups? The extinction of an arbitrary phylogenetic segment at a stratigraphic boundary tells us nothing.
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Mel’nikov, N. V. "The Vendian–Cambrian Cyclometric Stratigraphic Scale for the Southern and Central Siberian Platform". Russian Geology and Geophysics 62, n. 08 (1 agosto 2021): 904–13. http://dx.doi.org/10.2113/rgg20214339.

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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.
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Idrissi, Assia, Mohamed Saadi, Yassir Astati, Ali Bouayachi e Kawtar Benyas. "Mapping of Genetic Sequences of the Cambrian Series in the Jbel Saghro Massif, Eastern Anti-Atlas, Morocco: Implications for Eustatic and Tectonic Controls". Iraqi Geological Journal 55, n. 1D (30 aprile 2022): 1–20. http://dx.doi.org/10.46717/igj.55.1d.1ms-2022-04-17.

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In this paper, a sedimentological and sequence stratigraphy analysis was performed on Lower and Middle Cambrian deposits of Jbel Saghro, Eastern Anti-Atlas. The field data analysis and the application of sequence stratigraphy concepts were used to classify sedimentary processes and depositional environment, and to define the Lower to Middle Cambrian basin’s detailed geometry. The Cambrian sedimentation of northeastern Saghro indicates a deltaic environment, which is composed of two depositional sequences. These sequences are made of a transgressive system-tract with retrograding sediments and a highstand system tract with prograding sediments. In response to sea-level change, these system-tracts were formed by several genetic units, and limited by various stratigraphic surfaces. The genetic unit stacking-patterns combined with the study of synsedimentary tectonics enabled to follow the sedimentary record’s Spatio-temporal evolution and its three-dimensional geometry. The study area deposits display significant dissimilarities in thickness. The western part shows a Lower Cambrian hiatus and an important reduction of the thickness in the Middle Cambrian deposits. However, the marine trend (progradation/retrogradation) remains similar in the study area. This suggests the same eustatic origin of all genetic sequences and variations in their preservation rate. This configuration is the result of differential subsidence that affected the Anti-Atlas during the Cambrian.
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JACQUET, SARAH M., THOMAS BROUGHAM, CHRISTIAN B. SKOVSTED, JAMES B. JAGO, JOHN R. LAURIE, MARISSA J. BETTS, TIMOTHY P. TOPPER e GLENN A. BROCK. "Watsonella crosbyi from the lower Cambrian (Terreneuvian, Stage 2) Normanville Group in South Australia". Geological Magazine 154, n. 5 (21 ottobre 2016): 1088–104. http://dx.doi.org/10.1017/s0016756816000704.

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AbstractCorrelation of lower Cambrian strata is often confounded by provincialism of key fauna. The widespread occurrence of the micromollusc Watsonella crosbyi Grabau, 1900 is therefore an important biostratigraphic signpost with potential for international correlation of lower Cambrian successions. Previous correlations of W. crosbyi from Australia (Normanville Group) suggested an Atdabanian- to Botoman-equivalent age. However, in the upper part of the Mount Terrible Formation, stratigraphic ranges of W. crosbyi and Aldanella sp. cf. golubevi overlap prior to the incoming of vertically burrowed ‘piperock’, which is indicative of an age no earlier than Cambrian Stage 2. The stratigraphic range of W. crosbyi in the Normanville Group, South Australia correlates with the ranges of the taxon in China, France, Mongolia and Siberia (though not Newfoundland). The new Australian data add further support for considering the first occurrence of W. crosbyi a good potential candidate for defining the base of Cambrian Stage 2. The stratigraphic range of W. crosbyi through the lower Cambrian Normanville Group has been determined based on collections from measured sections. Although rare, W. crosbyi is part of an assemblage of micromolluscs including Bemella sp., Parailsanella sp. cf. murenica and a sinistral form of Aldanella (A. sp. cf. A. golubevi). Other fauna present include Australohalkieria sp., Eremactis mawsoni, chancelloriids and Cupitheca sp.
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Parkhaev, P. Yu. "The Cambrian molluscs of Australia: overview of taxonomy, biostratigraphy and paleobiogeography". Стратиграфия 27, n. 2 (25 marzo 2019): 52–79. http://dx.doi.org/10.31857/s0869-592x27252-79.

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Cambrian malacofauna of Australia is among the most taxonomically diverse among time equivalents. By a number of valid mollusc species Australian Cambrian competes with Siberian and Chinese formations. Up to date, 80 valid species and 12 forms in open nomenclature, apparently representing new undescribed taxa, have been recorded from the Lower–Middle Cambrian successions of Australia. In addition, 6 species names can be considered as junior synonyms. Distribution ranges of mollusc species plotted over the modern stratigraphic scheme reveal four major molluscan evolutionary assemblages in the interval of Tommotian–Undillan stages. In paleogeographic aspect, the Cambrian malacofauna of Australia has 29 species in common with Siberian Platform, Kazakhstan, Altai-Sayan, Transbaikalia, Mongolia, South and North China, Morocco, Antarctic, Europe (Denmark, Germany), Greenland, North America, and New Zealand, providing important correlation links between these regional stratigraphic schemes.
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Hughes, Nigel C., Gerald O. Gunderson e Michael J. Weedon. "Late Cambrian conulariids from Wisconsin and Minnesota". Journal of Paleontology 74, n. 5 (settembre 2000): 828–38. http://dx.doi.org/10.1017/s0022336000033035.

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Several localities within the heterolithic facies of the St. Lawrence Formation (Upper Cambrian) of Wisconsin and Minnesota yield specimens with phosphatic exoskeletons, quadrate cross sections composed of four equidimensional faces each bearing a midline, and possible holdfast attachment during life. These specimens are here referred to the order Conulariida, class Scyphozoa. Their fine, tuberculate surface ornament and serially invaginated midline structure serve to define a new genus, Baccaconularia, to which two new species, B. robinsoni and B. meyeri, are assigned. Conularia cambria Walcott 1890, also from the Cambrian of the northern Mississippi Valley and long dismissed as a misidentified trilobite fragment, is illustrated photographically for the first time. This species occurs in rocks stratigraphically beneath the St. Lawrence Formation. Specimens assigned to this species by Walcott are conulariids, but lack features now considered diagnostic of either Conularia or Baccaconularia. Walcott's material is insufficient to permit detailed taxonomic evaluation, and we isolate this name to this material, pending the collection of additional, better preserved specimens. Together, Baccaconularia and Conularia cambria contain the oldest large conulariids, and these narrow a stratigraphic gap between other large conulariids known from the Lower Ordovician onwards, and smaller fossils with conulariid affinities known only from Lower Cambrian rocks.
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Li, Xing, e Mary Droser. "The development of Early Paleozoic shell concentrations: evidence from the Cambrian and Ordovician of the Great Basin". Paleontological Society Special Publications 6 (1992): 183. http://dx.doi.org/10.1017/s2475262200007437.

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Shell concentrations have constituted an important and conspicuous part of the stratigraphic record since the Early Cambrian. The paleontological and stratigraphic significance of shell beds is well understood, primarily from Mesozoic and Cenozoic examples. Lower Paleozoic fossil concentrations, however, have not received much attention. The Cambrian and Ordovician evolutionary radiations were two of the most significant events in the history of life and established the Cambrian and Paleozoic faunas respectively. In order to determine the effect of these radiations on the development of fossil accumulations, a systematic study of early Paleozoic shell beds was conducted in the Great Basin areas of California, Nevada, and Utah.In order to minimize taphonomic variations in original chemical and physical conditions, shell beds were compared from strata deposited in similar depositional environments from similar tectonic settings. Preliminary analysis of the shell beds from relatively pure carbonate facies and mixed carbonate and siliciclastic facies shows: 1) that shell concentrations became a significant stratigraphic feature in the later Early Cambrian; 2) the thickness and lateral extent of the shell beds increase from Early Cambrian to Middle Ordovician; 3) the abundance and internal complexity of the shell beds increase from Early Cambrian to Middle Ordovician; and 4) the Cambrian and Early Ordovician shell beds are primarily, if not exclusively, dominated by trilobites whereas the Middle Ordovician shell beds are dominated by brachiopods and ostracodes.These data show a temporal trend in the development of the early Paleozoic shell beds. The nature of the Cambrian and Ordovician shell beds differs qualitatively and quantitatively. There is an increase in physical scale, abundance, and internal complexity through time. The thickness and abundance of the trilobite beds increase through the Cambrian. Interestingly, although trilobites were still diverse and abundant, they did not commonly generate thick trilobite beds after the Late Cambrian. The early Middle Ordovician is a critical time in the development of early Paleozoic shell beds. A variety of monotaxic and polytaxic shell beds, including 6m thick composite beds, first appeared at this time. While the brachiopods and ostracodes generate laterally extensive, commonly monotaxic, shell beds, the gastropods and bryozoans only formed lenticular concentrations.
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Sumrall, Colin D., e Samuel Zamora. "A columnal-bearing eocrinoid from the Cambrian Burgess Shale (British Columbia, Canada)". Journal of Paleontology 89, n. 2 (marzo 2015): 366–68. http://dx.doi.org/10.1017/jpa.2014.54.

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AbstractA new eocrinoid ?Ubaghsicystis sp. from the middle Cambrian (Series 3, Stage 5) Burgess Shale is reported based on a single known specimen. This species extends the stratigraphic range of columnal-bearing eocrinoids in Laurentia significantly from Cambrian Stage 7 (Guzhangian) to Stage 5. It increases the diversity of echinoderms in this well-known fossil-Lagerstätte, provides the oldest evidence of columnal-bearing eocrinoids from Laurentia, and further documents the cosmopolitan distribution of middle Cambrian echinoderm clades.
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Clausen, Sébastien, J. Javier Álvaro, Léa Devaere, Per Ahlberg e Loren E. Babcock. "The Cambrian explosion: Its timing and stratigraphic setting". Annales de Paléontologie 101, n. 3 (luglio 2015): 153–60. http://dx.doi.org/10.1016/j.annpal.2015.07.001.

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Myrow, P. M., N. C. Hughes e N. R. McKenzie. "Reconstructing the Himalayan margin prior to collision with Asia: Proterozoic and lower Paleozoic geology and its implications for Cenozoic tectonics". Geological Society, London, Special Publications 483, n. 1 (21 novembre 2018): 39–64. http://dx.doi.org/10.1144/sp483.10.

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AbstractReconstructing the stratigraphic architecture of deposits prior to Cenozoic Himalayan uplift is critical for unravelling the structural, metamorphic, depositional and erosional history of the orogen. The nature and distribution of Proterozoic and lower Paleozoic strata have helped elucidate the relationship between lithotectonic zones, as well as the geometries of major bounding faults. Stratigraphic and geochronological work has revealed a uniform and widespread pattern of Paleoproterozoic strata >1.6 Ga that are unconformably overlain by <1.1 Ga rocks. The overlying Neoproterozoic strata record marine sedimentation, including a Cryogenian diamictite, a well-developed carbonate platform succession and condensed fossiliferous Precambrian–Cambrian boundary strata. Palaeontological study of Cambrian units permits correlation from the Indian craton through three Himalayan lithotectonic zones to a precision of within a few million years. Detailed sedimentological and stratigraphic analysis shows the differentiation of a proximal realm of relatively condensed, nearshore, evaporite-rich units to the south and a distal realm of thick, deltaic deposits to the north. Thus, Neoproterozoic and Cambrian strata blanketed the northern Indian craton with an extensive, northward-deepening, succession. Today, these rocks are absent from parts of the inner Lesser Himalaya, and the uplift and erosion of these proximal facies explains a marked change in global seawater isotopic chemistry at 16 Ma.
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Tesi sul tema "Stratigraphic Cambrian"

1

Eagan, Keith E. "Paleoenvironmental and Stratigraphic Interpretation of the Middle Cambrian Ute Formation, Northern Utah". DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/6791.

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The Middle Cambrian Ute Formation includes some 200 m of cyclically alternating carbonates and mud rocks. These are arranged in eight to nine, meter-scale, shallowing-upwards packages, representing deposition under predominantly subtidal conditions. The packages consist of vertical sequences of shale, silty limestone, oncolitic packstone, and oolitic grainstone that exhibit little variance in this general pattern. Small-scale unconformities separate the packages. The inferred depositional environment consists of an intrashelf basin that has a peritidal platform near its margins. The craton, which supplied most of the terrigenous sediment, was situated to the south (Cambrian orientation), and located near the equator. One cycle includes a stromatolite biostrome that is distributed across more than 1500 km2 in northern Utah and southern Idaho. Stromatolites range from mound-like to club-shaped to columnar and reach up to 2 min vertical dimension, and 0.15 min diameter. These large columnar structures were apparently established just basinward of an oolitic shoal. These ancient stromatolites, which are in many ways similar to those stromatolites recently reported from the Bahamas, contain many clues that suggest that they grew in normal marine conditions. These findings require a rethinking of the commonly held belief that Phanerozoic columnar stromatolites are indicators of restricted, hypersaline conditions. Analysis of several orders of laminae in Ute Formation stromatolites indicates periodicity in accumulation from which yearly accumulation rates may be inferred. Values obtained for growth rate range from 4.39-4.88 cm/yr. Such rates of accumulation are in accord with those documented for ancient stromatolites from the Bitter Springs Formation. Thus, even considering the occurrence of hiatal surfaces within the stromatolites, the duration of the columnar-stromatolite horizon probably encompasses 10-2 - 10-3 yr. The biostrome's position in the sequence of cycles and the changes in stromatolite morphology across depositional dip suggest that the biostrome may be essentially isochronous across its outcrop area and, thus, may be viewed as a bioevent horizon. The stromatolites also contribute to a better understanding of the paleogeography of the study area during the Middle Cambrian by providing information on relative energy levels and flow directions. (212 pages)
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Dilliard, Kelly Ann. "Sequence stratigraphy and chemostratigraphy of the Lower Cambrian Sekwi Formation, Northwest Territories, Canada". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Spring2006/K%5FDilliard%5F042406.pdf.

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Osleger, David Allen. "Cyclostratigraphy of Late Cambrian cyclic carbonates : an interbasinal field and modelling study, U.S.A. /". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03262008-175224/.

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Turner, Bronwyn Louise. "Cambrian black shales in the Karinya Syncline : stratigraphic distribution, sedimentology and kerogen composition /". Title page, table of contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09SB/09sbt944.pdf.

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Baghiyan-Yazd, Mohammad Hassan. "Palaeoichnology of the terminal Proterozoic-Early Cambrian transition in central Australia : interregional correlation and palaeoecology". Title page, table of contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phb1445.pdf.

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Sundberg, Frederick Allen. "Morphological diversification of the ptychopariid trilobites in the Marjumiid biomere (Middle to Upper Cambrian)". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07102007-142511/.

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Malhame, Pierre. "Quartz arenites of the uppermost Cambrian-lowermost Ordovician Kamouraska Formation, Québec, Canada : gravity flow deposits of eolian sand in the deep sea". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101868.

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The uppermost Cambrian-Lower Ordovician Kamouraska Formation in the external Humber Zone of the Quebec Appalachians consists of dominant thick massive to graded quartz arenite beds, subordinate pebble conglomerate and intercalated thin shale and siltstone beds. It was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the Iapetus Ocean. Turbidity currents deposited beds with turbidite structure divisions. The sandstones consist of well sorted, well rounded quartz sand with frosted grains. Scanning electron microscopy reveals the presence of textures supporting eolian transport before redeposition in the deep sea. The Kamouraska quartz arenites are considered an ancient equivalent of Pleistocene eolian-sand turbidites on an abyssal plain off West Africa consisting of Sahara sand. Sand provenance is attributed to eolian equivalents of the Cairnside Formation of the Potsdam Group. The quartz arenites of the Kamouraska Formation provide a variant to tectonic sandstone provenance proposed in the scheme of Dickinson and Suczek (1979).
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Singh, Updesh. "Late Precambrian and Cambrian carbonates of the Adelaidean in the Flinders Ranges, South Australia : a petrographic, electron microprobe and stable isotope study /". Title page, abstract and contents only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phs1792.pdf.

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Tremblay, James Vincent. "Trilobites and strata of the Lower and Middle Cambrian Peyto, Mount Whyte and Naiset Formations, Alberta and British Columbia /". *McMaster only, 1996.

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Dunster, John N. "Sedimentology of the Ouldburra Formation (Early Cambrian), northeastern Officer Basin". Title page, contents and abstract only, 1987. http://web4.library.adelaide.edu.au/theses/09SM/09smd926.pdf.

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Libri sul tema "Stratigraphic Cambrian"

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Jankauskas, Tadas. Cambrian stratigraphy of Lithuania. Vilnius: Geologijos institutas, 2002.

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Controversy in Victorian geology: The Cambrian-Silurian dispute. Princeton, N.J: Princeton University Press, 1986.

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W, Cowie J., e Brasier M. D, a cura di. The Precambrian-Cambrian boundary. Oxford: Clarendon Press, 1989.

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Ineson, Jon R. Cambrian shelf stratigraphy of North Greenland. Copenhagen, Denmark: Geological Survey of Denmark and Greenland, Ministry of Environment and Energy, 1997.

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Holmes, Thom. Early life: The Cambrian period. New York: Chelsea House, 2008.

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Aceñolaza, Guillermo Federico, e Silvio Peralta. Cambrian from the southern edge. San Miguel de Tucumán, Républica Argentina: Consejo Nacional de Investigaciones Cientif́icas y Técnicas, Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, 2000.

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Mokrik, Robert. The palaeohydrogeology of the Baltic Basin: Vendian & Cambrian. Tartu: Institute of Geology, Lithuania, 1997.

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Harris, David C. Cambrian hydrocarbon potential indicated in Kentucky's Rome Trough. [Lexington, Ky.]: Kentucky Geological Survey, 1996.

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Secord, James A. Controversy in Victorian geology: The Cambria-Silurian dispute. Oxford: Princeton University Press, 1990.

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E, Babcock Loren, e Lin Huanling, a cura di. Polymerid trilobites from the Cambrian of northwestern Hunan, China. Beijing: Science Press, 2006.

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Capitoli di libri sul tema "Stratigraphic Cambrian"

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Traverse, Alfred. "Stratigraphic Palynology–Precambrian, Cambrian, Ordovician". In Paleopalynology, 155–88. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-5610-9_6.

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Huntoon, Peter W. "Cambrian stratigraphic nomenclature,Grand Canyon, Arizona: Mappers nightmare". In Geology of Grand Canyon, Northern Arizona (with Colorado River Guides): Lee Ferry to Pierce Ferry, Arizona, 128–30. Washington, D. C.: American Geophysical Union, 1989. http://dx.doi.org/10.1029/ft115p0128.

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Christie-Blick, Nicholas, e Marjorie Levy. "Stratigraphic and tectonic framework of Upper Proterozoic and Cambrian rocks in the western United States". In Late Proterozoic and Cambrian Tectonics, Sedimentation, and Record of Metazoan Radiation in the Western United States: Pocatello, Idaho, to Reno, Nevada 20–29 July, 1989, 7–21. Washington, D. C.: American Geophysical Union, 1989. http://dx.doi.org/10.1029/ft331p0007.

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Brasier, Martin D. "The Basal Cambrian Transition and Cambrian Bio-Events (From Terminal Proterozoic Extinctions to Cambrian Biomeres)". In Global Events and Event Stratigraphy in the Phanerozoic, 113–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-79634-0_8.

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Dorjnamjaa, D., B. Enkhbaatar e G. Altanshagai. "Precambrian and Cambrian Regional Stratigraphy of Mongolia". In Springer Geology, 391–95. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04364-7_76.

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Palmer, A. R. "Day 0: Early and Middle Cambrian stratigraphy of Frenchman Mountain, Nevada". In Cambrian and Early Ordovician Stratigraphy and Paleontology of the Basin and Range Province, Western United States: Las Vegas, Nevada to Salt Lake City, Utah, July 1–7, 1989, 14–16. Washington, D. C.: American Geophysical Union, 1989. http://dx.doi.org/10.1029/ft125p0014.

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Palmer, A. R., e Stephen M. Rowland. "Day 1: Early Cambrian stratigraphy and paleontology, southern Great Basin, California-Nevada". In Cambrian and Early Ordovician Stratigraphy and Paleontology of the Basin and Range Province, Western United States: Las Vegas, Nevada to Salt Lake City, Utah, July 1–7, 1989, 17–27. Washington, D. C.: American Geophysical Union, 1989. http://dx.doi.org/10.1029/ft125p0017.

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Zellouf, Khemissi, e Hamid Aït Salem. "Sequence Stratigraphy of the Cambrian and Ordovician Series in the Illizi Basin (Algeria)". In Springer Geology, 815–20. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04364-7_153.

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Sukhov, Sergey. "Sedimentological Causes of Some Problems in the Cambrian Stratigraphy of the Siberian Platform". In Springer Geology, 453–56. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04364-7_87.

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Azmy, Karem, Gabriella Bagnoli, Svend Stouge e Uwe Brand. "High-Resolution Carbon-Isotope Stratigraphy of the Cambrian–Ordovician GSSP: An Enhanced International Correlation Tool". In Springer Geology, 233–37. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-04364-7_47.

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Atti di convegni sul tema "Stratigraphic Cambrian"

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Hughes, G. M., e A. Al Lawati. "An updated Stratigraphic Framework for the Haima Supergroup of North Oman". In Seventh Arabian Plate Geology Workshop: Pre-Cambrian to Paleozoic Petroleum Systems in the Arabian Plate. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201900227.

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MacNaughton, Robert B., Karen M. Fallas e Wing C. Chan. "STRATIGRAPHIC EVIDENCE FOR EDIACARAN AND EARLY CAMBRIAN EXTENSIONAL FAULTING, MACKENZIE MOUNTAINS, NORTHWESTERN CANADA". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-295926.

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Jeffrey, Matthew Jarrell, John Warren Huntley, James D. Schiffbauer, David A. Fike e Kevin L. Shelton. "STRATIGRAPHIC VARIATION OF THE SPICE EVENT IN UPPER CAMBRIAN CARBONATES OF SOUTHERN MISSOURI". In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-282908.

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Farrell, Thomas, Hannah Cothren, Laura J. Crossey, Carol Dehler, John R. Foster, James W. Hagadorn, Karl E. Karlstrom, Fred A. Sundberg, Mark D. Schmitz e Mark Webster. "NUMERICAL CALIBRATION OF WESTERN LAURENTIAN CAMBRIAN STRATIGRAPHIC SUCCESSIONS INTO THE GLOBAL GEOLOGIC TIME SCALE". In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-368486.

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Plechacek, Amy, Madeleine Mathews, Sean Scott, Madeline Gotkowitz e Matthew Ginder-vogel. "ASSESSING RADIUM LEACHING POTENTIAL FROM STRATIGRAPHIC UNITS WITHIN THE MIDWESTERN CAMBRIAN-ORDOVICIAN AQUIFER SYSTEM". In GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-365448.

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Maguire, Henry C., Charlotte Mehrtens, Jonathan J. Kim e Ed Romanowicz. "APPLICATION OF GEOPHYSICAL METHODS TO STRATIGRAPHIC PROBLEMS IN THE LOWER CAMBRIAN MONKTON FORMATION: NW VERMONT". In 53rd Annual GSA Northeastern Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018ne-311020.

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Lasemi, Yaghoob, e Zohreh Askari Khorasgani. "STRATIGRAPHIC VARIABILITY, SECONDARY POROSITY DEVELOPMENT, AND CORRELATION OF THE CAMBRIAN POTOSI DOLOMITE ACROSS THE ILLINOIS BASIN". In GSA 2020 Connects Online. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020am-359811.

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Allard, J., S. Roussé, D. Savva, B. Murat, F. Saint-Ange, M. Djidjeli, C. Basuyau e A. Lounes. "Emerging unconventional plays in western Algerian Saharan platform: tectono-stratigraphic approach of Cambrian to Devonian units". In EAGE/ALNAFT Geoscience Workshop. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.2019x60047108.

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Hageman, Steven J. "SKOLITHOS LIFE ASSEMBLAGES AS SEDIMENTATION RATE AND “STRATIGRAPHIC UP” INDICATORS: PSEDUO-SPREITEN IN EARLY CAMBRIAN TRACE FOSSILS". In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-344245.

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Weichert, Wesley Donald, e Kevin Ray Evans. "STRATIGRAPHIC ANALYSIS OF CARBON ISOTOPE AND GAMMA-RAY RECORDS OF UPPER CAMBRIAN CARBONATE CYCLES FROM UTAH AND NEVADA". In Joint 52nd Northeastern Annual Section and 51st North-Central Annual GSA Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017ne-291424.

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Rapporti di organizzazioni sul tema "Stratigraphic Cambrian"

1

Cecile, M. P., B. S. Norford, G. S. Nowlan e T. T. Uyeno. Lower Paleozoic stratigraphy and geology, Richardson Mountains, Yukon (with stratigraphic and paleontological appendices). Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329454.

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Abstract (sommario):
The Richardson Trough was a rift basin on the southern margin of an ancestral Iapetus Ocean. It was part of a complex paleogeography that included at least two major rift basins on western Franklinian and northern Cordilleran continental shelves. This paleogeography included the Ogilvie Arch, Porcupine Platform, Blackstone 'supra-basin', Babbage Basin, Husky Lakes Arch, Richardson Trough, Mackenzie Arch, Lac des Bois Platform, and the White Mountains and Campbell uplifts. The Richardson Trough was the failed arm of a triple rift system that formed when an early Paleozoic Iapetus Ocean developed north of the trough. The Richardson Trough displays a classic 'steer's head' profile with two rift fill cycles. The first features late early to middle late Cambrian rifting and late late Cambrian to late Early Ordovician post-rift subsidence; the second, late Early Ordovician to early Silurian rifting and late early Silurian to early Middle Devonian post-rift subsidence. Lower Paleozoic strata exposed in the Richardson Trough range in age from middle Cambrian to early Middle Devonian and are similar to strata in their sister rift, the Misty Creek Embayment. Before this study, the stratigraphic units defined for the Richardson Trough were the Slats Creek Formation and the Road River Formation. Here, the Slats Creek Formation and a new Road River Group are recognized. In order, this group consists of the middle and/or late Cambrian to Early Ordovician Cronin Formation; the early Early Ordovician to latest early Silurian Mount Hare Formation; the early Silurian to late Silurian Tetlit Formation; and the late Silurian to early Middle Devonian Vittrekwa Formation. These Road River Group strata are unconformably overlain by the late Middle to Late Devonian Canol Formation (outcrop) and by the Early Devonian Tatsieta Formation (subsurface).
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MacNaughton, R. B., e K. M. Fallas. Neoproterozoic-Cambrian stratigraphy of the Mackenzie Mountains, northwestern Canada, part IV: a stratigraphic reference section for the Ediacaran-Cambrian transition in NTS 95-M (Wrigley Lake map area). Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329217.

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A composite reference section for the upper Ediacaran and lower Cambrian is documented for a location near Moose Horn River in Wrigley Lake map area (NTS 95-M), Mackenzie Mountains, Northwest Territories. Four measured stratigraphic sections cover, in ascending order: the uppermost Sheepbed Formation; the informal Sheepbed carbonate; the lower, middle, and upper members of the Backbone Ranges Formation; the Sekwi Formation; and the lowermost beds of the Rockslide Formation. The uppermost Sheepbed Formation is dominated by dark-weathering shale and siltstone. The Sheepbed carbonate (440 m) lies conformably on the Sheepbed Formation and consists of limestone, dolostone, and dolomitic siltstone, including several horizons of rudstone with clasts up to boulder size. The upper surface of the Sheepbed carbonate has been eroded and the unit thins to a zero edge to the east. The lower member of the Backbone Ranges Formation (253 m) is heterolithic, including interbedded quartzose siltstone and quartzose sandstone, quartz arenite (locally with horizons of quartz pebbles), and dolostone to dolomitic sandstone. The middle member of the Backbone Ranges Formation (93 m) consists mainly of pink to grey-weathering limestone with red mudstone partings. The upper member (501.5 m) is dominated by quartz arenite, but also contains intervals of siltstone. Partway through the upper member there is a marker unit of dolostone to dolomitic sandstone that previous work suggests is a tongue of the Ediacaran Risky Formation. Based on regional correlations, the top of this marker may approximate the Ediacaran-Cambrian boundary in this section. The Sekwi Formation lies abruptly upon the Backbone Ranges Formation. The contact is unconformable at this locality and mapping in the area indicates eastward erosional removal of the upper member of the Backbone Ranges Formation beneath the Sekwi Formation. The Sekwi Formation here consists of variegated siltstone with lesser dolostone, limestone, and quartz sandstone. An abrupt contact with nodular limestone and grey shale of the overlying Rockslide Formation approximates the base of Cambrian Series 3.
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Lavoie, D. Stratigraphic framework for the Cambrian Chaudière Nappe in the external domain of the Humber Zone in the Quebec Re-entrant, and preliminary correlation with adjacent stratigraphic frameworks. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2002. http://dx.doi.org/10.4095/213237.

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Lavoie, D. Along-strike Upper Cambrian-Lower Ordovician stratigraphic nomenclature and framework for the external Humber Zone, from Quebec City to Gaspé. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1998. http://dx.doi.org/10.4095/209528.

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Fallas, K. M., e R. B. MacNaughton. Bedrock mapping and stratigraphic studies in the Mackenzie Mountains, Franklin Mountains, Colville Hills, and adjacent areas of the Northwest Territories, Geo-mapping for Energy and Minerals program 2009-2019. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/326093.

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Abstract (sommario):
The Geo-mapping for Energy and Minerals (GEM) program provided an opportunity to update bedrock geological maps for nearly 92 000 km2 of the northwestern portion of the mainland area of the Northwest Territories. Twenty-four new maps (at the scale of 1:100 000 or 1:250 000) cover a region from the Colville Hills southwestward into the Mackenzie Mountains, including areas of significant mineral and energy resource potential. New mapping was informed by archived Geological Survey of Canada data, notably from Operation Norman (1968-1970), as well as by public-domain industry data. Maps incorporate numerous stratigraphic revisions that postdate Operation Norman, including GEM program innovations affecting Neoproterozoic (specifically Tonian and Ediacaran), Cambrian, and Ordovician units. In this paper, the mapping effort and stratigraphic revisions are documented, a preliminary treatment of structural geology is provided, and related subsurface studies are summarized. Following GEM, GIS-enabled bedrock maps will be available for a swath of territory stretching from the edge of the Selwyn Basin, near the Yukon border, to the Brock Inlier in the northeastern portion of the mainland area of the Northwest Territories.
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MacNaughton, R. B. Neoproterozoic-Cambrian stratigraphy of the Mackenzie Mountains, northwestern Canada, part II: archival stratigraphic data for the Backbone Ranges Formation and related units, Mackenzie Mountains, Northwest Territories, Canada (NTS 95-L and 105-P). Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2020. http://dx.doi.org/10.4095/327238.

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Mueller, C., S. J. Piercey, M. G. Babechuk e D. Copeland. Stratigraphy and lithogeochemistry of rocks from the Nugget Pond Deposit area, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328989.

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Stratigraphic and lithogeochemical data were collected from selected drill core from the Nugget Pond gold deposit in the Betts Cove area, Newfoundland. The stratigraphy consists of a lower unit of basaltic rocks that are massive to pillowed (Mount Misery Formation). This is overlain by sedimentary rocks of the Scrape Point Formation that consist of lower unit of turbiditic siltstone and hematitic cherts/iron formations (the Nugget Pond member); the unit locally has a volcaniclastic rich-unit at its base and grades upwards into finer grained volcaniclastic/turbiditic rocks. This is capped by basaltic rocks of the Scrape Point Formation that contain pillowed and massive mafic flows that are distinctively plagioclase porphyritic to glomeroporphyritic. The mafic rocks of the Mount Misery Formation have island arc tholeiitic affinities, whereas Scrape Point Formation mafic rocks have normal mid-ocean ridge (N-MORB) to backarc basin basalt (BABB) affinities. One sample of the latter formation has a calc-alkalic affinity. All of these geochemical features are consistent with results and conclusions from previous workers in the area. Clastic sedimentary rocks and Fe-rich sedimentary rocks of the Scrape Point Formation have features consistent with derivation from local, juvenile sources (i.e., intra-basinal mafic rocks). The Scrape Point Formation sedimentary rocks with the highest Fe/Al ratios, inferred to have greatest amount of hydrothermally derived Fe, have positive Ce anomalies on Post-Archean Australian Shale (PAAS)-normalized trace element plots. These features are consistent with having formed via hydrothermal venting into an anoxic/ sub-oxic water column. Further work is needed to test whether these redox features are a localized feature (i.e., restricted basin) or a widespread feature of the late Cambrian-early Ordovician Iapetus Ocean, as well as to delineate the role that these Fe-rich sedimentary rocks have played in the localization of gold mineralization within the Nugget Pond deposit.
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Mueller, C., S. J. Piercey, M. G. Babechuk e D. Copeland. Stratigraphy and lithogeochemistry of the Goldenville horizon and associated rocks, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328990.

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The Goldenville horizon in the Baie Verte Peninsula is an important stratigraphic horizon that hosts primary (Cambrian to Ordovician) exhalative magnetite and pyrite and was a chemical trap for younger (Silurian to Devonian) orogenic gold mineralization. The horizon is overlain by basaltic flows and volcaniclastic rocks, is intercalated with variably coloured argillites and cherts, and underlain by mafic volcaniclastic rocks; the entire stratigraphy is cut by younger fine-grained mafic dykes and coarser gabbro. Lithogeochemical signatures of the Goldenville horizon allow it to be divided into high-Fe iron formation (HIF; &amp;gt;50% Fe2O3), low-Fe iron formation (LIF; 15-50% Fe2O3), and argillite with iron minerals (AIF; &amp;lt;15% Fe2O3). These variably Fe-rich rocks have Fe-Ti-Mn-Al systematics consistent with element derivation from varying mineral contributions from hydrothermal venting and ambient detrital sedimentation. Post-Archean Australian Shale (PAAS)-normalized rare earth element (REE) signatures for the HIF samples have negative Ce anomalies and patterns similar to modern hydrothermal sediment deposited under oxygenated ocean conditions. The PAAS-normalized REE signatures of LIF samples have positive Ce anomalies, similar to hydrothermal sediment deposited under anoxic to sub-oxic conditions. The paradoxical Ce behaviour is potentially explained by the Mn geochemistry of the LIF samples. The LIF have elevated MnO contents (2.0-7.5 weight %), suggesting that Mn from hydrothermal fluids was oxidized in an oxygenated water column during hydrothermal venting, Mn-oxides then scavenged Ce from seawater, and these Mn-oxides were subsequently deposited in the hydrothermal sediment. The Mn-rich LIF samples with positive Ce anomalies are intercalated with HIF with negative Ce anomalies, both regionally and on a metre scale within drill holes. Thus, the LIF positive Ce anomaly signature may record extended and particle-specific scavenging rather than sub-oxic/redox-stratified marine conditions. Collectively, results suggest that the Cambro-Ordovician Taconic seaway along the Laurentian margin may have been completely or near-completely oxygenated at the time of Goldenville horizon deposition.
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Aitken, J. D. Cambrian and Lower Ordovician-Sauk Sequence [Chapter 4: Stratigraphy]. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1993. http://dx.doi.org/10.4095/192360.

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Dixon, J. Cambrian stratigraphy of the northern Interior Plains, Northwest Territories. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1997. http://dx.doi.org/10.4095/209239.

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