Chronology of tectonothermal activity in the western Avalon Zone of the Newfoundland Appalachians

Dallmeyer, R. D.; Hussey, E. M.; O’Brien, S. J.; O'Driscoll, C. F.

doi:10.1139/e83-034

Cited by 18 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2). These rocks are deformed and sericitized, with a cleavage typical in orientation and style of the numerous fault zones that result from Acadian thrusting throughout the western Avalon Terrane (Strong et al 1978;Dallmeyer et al 1983). The zircons have a simple igneous habit, but the data have an unusual discordance pattern (analyses 5 -9, Table 1, Fig.…”

Section: New Data Methods and Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Precise U–Pb zircon dates from the Avalon Terrane in Newfoundland

Krogh¹,

Strong²,

O’Brien³

et al. 1988

Can. J. Earth Sci.

Self Cite

143

View full text Add to dashboard Cite

The following new U–Pb dates are provided for zircons from volcanic and intrusive rocks of the Avalon Terrane of Newfoundland: Burin Group ophiolite (Wandsworth pegmatitic gabbro), [Formula: see text]; Marystown Group ash-flow tuff, [Formula: see text]; Rock Harbour Group rhyolite clast in conglomerate, [Formula: see text]; Harbour Main Group ash-flow tuff, [Formula: see text]; Harbour Main Group flow-banded rhyolite, [Formula: see text]; porphyritic rhyolite plug intruding Harbour Main Group, 632 ± 2 Ma; Holyrood Granite, [Formula: see text]; rhyolite dyke, Harbour Main Group, [Formula: see text]; and welded ash-flow tuff, "Grand Beach porphyry," [Formula: see text]. All of the dated zircons are simple, single-age populations with no trace of inheritance. These dates confirm that the ophiolitic Burin Group represents an older and separate event that correlates precisely with the Bou Azzer ophiolite of Morocco and that the Rock Harbour Group does not represent continental volcanism that preceded that event. The Rock Harbour, Marystown, and Harbour Main groups and the Holyrood Granite (632–608 Ma) are all part of the younger 650–550 Ma pulse of Pan-African orogenesis that affected a broad area extending through Africa, Asia, western Europe, southern England and Wales, and eastern North America. However, a shortage of high-precision dates throughout these terranes precludes very exact correlations and thus very exact interpretations in terms of specific tectonic or magmatic events. Although these dates require some revisions in the stratigraphy of the Newfoundland Avalon Terrane, they do not support suggestions that the Avalon Terrane comprises a "collage of suspect terranes." The age of the Grand Beach porphyry (394 Ma) places it squarely with the Acadian granites of the Appalachians and removes it from consideration as part of the Marystown Group.

show abstract

Section: New Data Methods and Resultsmentioning

confidence: 99%

“…Although some radiometric dates using Rb-Sr, U -Pb, and 40Ar/39Ar methods are available (e. g . , Dallmeyer et al 1981a, Dallmeyer et al , 1981b, Dallmeyer et al , 1983, there is a great need for high-precision dates if we are to reach a full understanding of the stratigraphic evolution and tectonic significance of the Avalon Terrane.…”

Section: Introductionmentioning

confidence: 99%

Precise U–Pb zircon dates from the Avalon Terrane in Newfoundland

Krogh¹,

Strong²,

O’Brien³

et al. 1988

Can. J. Earth Sci.

Self Cite

143

View full text Add to dashboard Cite

show abstract

“…Location of Grey River, Cinq Cerf Bay, and Hermitage Flexure also shown in Figure 1. areas record regional postmetamorphic cooling along the eastern margin of the orogen at this time (Dallmeyer et al, 1981(Dallmeyer et al, , 1983Chorlton and Dallmeyer, 1986).…”

Section: Early Paleozoic Evolution Of the Neoproterozoic Rocksmentioning

confidence: 95%

“…Kerr et al, 1993) and which was accompanied by postmetamorphic cooling (Dallmeyer et al, 1981(Dallmeyer et al, , 1983. Ductile structures of Silurian age in both the Hermitage Flexure and along the northwestern edge of the Avalon Zone are crosscut by Devonian high-level plutons (S. J.…”

Section: Devonian Recordmentioning

confidence: 99%

“…Minor tilting and extensional block faulting related to the Avalonian Orogeny (Lilly, 1966;Rodgers, 1967Rodgers, , 1972 were seen as the only tectonic events of regional significance to have affected these rocks prior to the deposition of an early Paleozoic platformal succession, widely viewed (inaccurately, we argue) as the hallmark of the Avalonian orogenic belt. Tectonism of Avalonian rocks was viewed to be of mainly post-Cambrian and pre-Late Devonian age, related to what was assumed to be initial accretion of the Avalon Zone to inboard Appalachian elements during Early to Middle Devonian Acadian orogenesis (e.g., Dallmeyer et al, 1983).…”

Section: Late Neoproterozoic Rocks Of the Avalon Zone (Sensu Stricto)mentioning

confidence: 99%

See 1 more Smart Citation

Late Neoproterozoic Avalonian and related peri-Gondwanan rocks of the Newfoundland Appalachians

O’Brien¹,

O'Brien²,

Dunning³

et al. 1996

Special Paper 304: Avalonian and Related Peri-Gondwanan Terranes of the Circum-North Atlantic

Self Cite

View full text Add to dashboard Cite

Distinct groupings of late Neoproterozoic tectonomagmatic and depositional events at 760 Ma, 685-670 Ma, 635-590 Ma and 590-545 Ma are recognized within the peri-Gondwanan margin of the Newfoundland Appalachians. This pre-Iapetan orogenic activity resulted in amalgamation of distinctive tectonic packages prior to deposition of a shale-rich platformal cover of terminal Neoproterozoic to Early Ordovician age, east of the Appalachian central mobile belt. The late Neoproterozoic successions chronicle, in part, the development of segments of a larger peri-Gondwanan orogenic system that was dispersed prior to, and variously reworked during, the protracted evolution of the southern Iapetus Ocean.The oldest orogenic events yet identified in the Newfoundland Avalonian belt occurred at and prior to 760 Ma and are manifest by the accumulation of submarine mafic volcanic rocks, the emplacement of oceanic gabbros, and the associated deposition of unique clastic and carbonate olistostromes. As early as 685 Ma, arc-related volcanic and associated arc-root plutonic complexes of felsic to intermediate composition developed along the orogenic belt in an overall contractional environment. These complexes, which are preserved together with amphibolite gneisses and associated intrusive rocks, were inhomogeneously deformed and then uplifted prior to the onset of widespread (635-590 Ma) volcanism, marine sedimentation, and coeval calc-alkaline plutonism, the products of which were deposited upon or emplaced into the 685-670 Ma basement. Locally, pre-600 Ma rocks have been inhomogeneously deformed prior to a complex volcanic, plutonic, and structural event (590-545 Ma), partly extensional and partly contractional in nature, during which the classical Ediacaranbearing and younger sedimentary successions of the Avalonian belt accumulated.Diverse tectonic elements that evolved prior to the Cambrian were variably dispersed at several times, perhaps most significantly during late Neoproterozoic orogenesis. Pronounced terminal Neoproterozoic and early Paleozoic tectonothermal events were recorded on the inboard Iapetan margin of the belt, while elsewhere, terminal Neoproterozoic through Cambro-Ordovician platformal sediments were deposited, in most cases without apparent hiatus. These contrasting peri-Gondwanan terranes were reamalgamated and again dispersed during complex transpressional orogenesis of Silurian age related to closure of the Iapetus Ocean, and ensuing collision of Gondwanan and Laurentian elements of the Appalachian orogen.

show abstract

The Avalon Zone: A Pan‐African terrane in the Appalachian Orogen of Canada

1983

Self Cite

View full text Add to dashboard Cite

The Precambrian sequences of the Avalon Zone in Canada (southeastern margin of the Appalachian Orogen) are interpreted as a Pan‐African orogenic belt incorporated into the Appalachian Orogen during Palaeozoic times as its southeastern margin. The Precambrian evolution of the Avalon Zone was genetically unrelated to subsequent Palaeozoic evolution. The Avalon Zone shows marked similarities in age, tectonic history, and facies development to the Pan‐African belts adjacent to the West African Craton. Precambrian evolution of the zone began with circa 800 Ma rifting of a sialic gneissic basement and deposition of a Middle Proterozoic(?) carbonate‐clastic cover sequence. Early crustal rifting was associated with localized partial melting and metamorphism. Limited crustal separation led to the restricted development of circa 760 Ma oceanic volcanics. Continued rifting and subsequent closure of these narrow ocean basins led to the eruption of widespread subaerial volcanic suites, block faulting, granite plutonism, and local, late Proterozoic sedimentary basin formation. Precambrian evolution of the zone terminated with the Avalonian Orogeny (circa 650‐600 Ma), a deformational event, the affects of which are most evident locally along the northwestern margin of the zone. The controlling features of the Proterozoic evolution of the Avalon Zone are a series of linear intracratonic troughs and small ocean basins that formed during thinning and separation of the crust by ductile spreading, rupture, and delamination (cf. Martin and Porada 1977). The variation in degree of crustal separation led to subsequent variation in orogenesis during late Proterozoic compression. The zone marks the original westward limit of Pan‐African activity and displays no apparent genetic link with the Appalachian Orogen in Canada until Devonian times.

show abstract

Chronology of tectonothermal activity in the western Avalon Zone of the Newfoundland Appalachians

Cited by 18 publications

References 24 publications

Precise U–Pb zircon dates from the Avalon Terrane in Newfoundland

Precise U–Pb zircon dates from the Avalon Terrane in Newfoundland

Late Neoproterozoic Avalonian and related peri-Gondwanan rocks of the Newfoundland Appalachians

The Avalon Zone: A Pan‐African terrane in the Appalachian Orogen of Canada

Contact Info

Product

Resources

About