Geology, Belleoram, Newfoundland

Anderson, F D

doi:10.4095/124106

Cited by 4 publications

(2 citation statements)

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“…Since the 1960s, geologists have highlighted three distinct features for the ‘lower Cambrian’ stratigraphy in the Avalon Zone: (a) discontinuous sedimentation episodically punctuated by angular discordances and paraconformities, in some cases associated with ‘folding’ (North, 1971 and references therein); (b) the abundance of scouring channels marking the contacts of several Cambrian formations, infilled with plutonic clasts derived from Neoproterozoic granitic bedrock, and pointing to contemporaneous uplift and erosive episodes; and (c) the presence of thin reddish to purple fossiliferous limestones that commonly pinch out over kilometres, grading laterally from metre‐thick beds and lenses to centimetre‐thick nodules aligned parallel to stratification (e.g. Anderson, 1965; Hutchinson, 1962; Jenness, 1963; McCartney, 1967; North, 1971). Other distinct exotic components, such as detrital muscovite and garnet, so abundant in the Random Formation and other Cambrian sandstones but virtually absent in Neoproterozoic bedrocks of SE Newfoundland, have been a matter of discussion (e.g.…”

Section: Geological and Stratigraphic Backgroundmentioning

confidence: 99%

Cambrian syn‐rift tectonic pulses at unconformity‐bounded carbonates in the Avalon Zone of Newfoundland, Canada

Álvaro

2021

Basin Research

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In the Avalon Zone of SE Newfoundland, several Terreneuvian to Cambrian Series 2 carbonate bodies occur associated with paraconformities and onlapping geometries. Their stratigraphic discontinuities and related gaps represent syn-rift episodes characterized by sharply tilted and downfaulted blocks and deposition of chaotic megabreccia beds and conglomerates on neighbouring footwall areas. Microbial and shelly carbonate production nucleated on tectonically unstable palaeohorsts, where stromatolitic crusts and mats commonly reflect the onset of hiatal stratigraphic diastems, and mud-mounds the episodic establishment of calm conditions. Short-term uplift episodes of rift shoulders led to unroofing of the Neoproterozoic basement (yielding granitoid clasts and input of reworked exotic clasts and allochthonous fossils from underlying Cambrian strata), localized subaerial exposure and karst features, and the development of synsedimentary fracture networks that provided favourable conduits and pathways for hydrothermal fluids. These carbonate beds host vein networks of carbonate-hosted polymetallic sulphide-sulphate-oxide mineral associations (Pb-Cu-Fe-barite stockworks). The mixture of parautochthonous and allochthonous bioclastic assemblages points to the record of event-concentration strata, which may clarify the long stratigraphic ranges of some involved microfossils. The Cambrian Avalonia rift and the offshore to basinal rift sector of the neighbouring Atlas-Ossa-Morena rift, preserved in the Moroccan northern High Atlas and Coastal Meseta, share common temperatewater carbonate facies and build-ups, lacking 'subtropical' indicators such as archaeocyathan-microbial reefs, ooidal shoals or evaporitic pseudomorphs. These diagnostic facies and minerals occur only in relatively stable, shallow-water rift branches, such as those preserved in the Anti-Atlas and the Ossa-Morena Zone (Iberian Massif).

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Section: Geological and Stratigraphic Backgroundmentioning

confidence: 99%

Cambrian syn‐rift tectonic pulses at unconformity‐bounded carbonates in the Avalon Zone of Newfoundland, Canada

Álvaro

2021

Basin Research

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“…Hutchinson ( 1962) found no conclusive evidence of a disconformity at the base of the fossiliferous Cambrian shales in Fortune Bay. In the intervening Placentia Bay area most previous workers (Anderson 1965;Rose 1948;Van Alstine 1948) included quartzites now assigned to the Random Formation in the Lower Cambrian, thus implying no disconformity there.…”

Section: The Upper Contact Of the Random Formationmentioning

confidence: 97%

New Fossil Localities and the Base of the Cambrian in Southeastern Newfoundland

Greene¹,

Williams²

1974

Can. J. Earth Sci.

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In the essentially continuous late Precambrian – Early Paleozoic succession of eastern Newfoundland, abundantly fossiliferous Cambrian shales are separated in most places from underlying strata by a quartzite-siltstone unit. This unit has been referred to the Random Formation in the Avalon-Bonavista area (east) and to the Blue Pinion Formation in the Fortune Bay area (west), and its age and significance in defining a Cambrian-Precambrian boundary have been in doubt for some time. An erosional disconformity at the top of the Random Formation has been interpreted as the base of the Cambrian by most authors. Recent stratigraphic studies indicate that both the Random and Blue Pinion Formations are parts of a laterally continuous lithologic unit and that the upper contact of this unit is gradational and conformable in central parts of its outcrop area. New fossil discoveries both within and beneath the Blue Pinion Formation indicate that the quartzite-siltstone unit is diachronous, and that its westernmost exposures are of Cambrian age.

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The Age and Origin of the Deepest Correlative Structures Recognized off Canada and Europe

LEFORT¹,

HAWORTH²

1979

Developments in Geotectonics

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Geology, Belleoram, Newfoundland

Cited by 4 publications

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Cambrian syn‐rift tectonic pulses at unconformity‐bounded carbonates in the Avalon Zone of Newfoundland, Canada

Cambrian syn‐rift tectonic pulses at unconformity‐bounded carbonates in the Avalon Zone of Newfoundland, Canada

New Fossil Localities and the Base of the Cambrian in Southeastern Newfoundland

The Age and Origin of the Deepest Correlative Structures Recognized off Canada and Europe

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