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

Krogh, T. E.; Strong, D. F.; O’Brien, S. J.; Papezik, V. S.

doi:10.1139/e88-045

Cited by 144 publications

(70 citation statements)

References 30 publications

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“…The protracted magmatic, metamorphic, and tectonic events related to the closure of Precambrian ocean basins and assembling of Gondwana have been termed 'Pan African' by Kennedy (1964) and more recently as 'Brasiliano -Pan African' by da Silva et al (2005). In the northern Appalachians, evidence for the breakup of Rodinia is recorded in the Avalon Terrane of Newfoundland by ophiolitic rocks that have yielded a U-Pb date of 763 ± 2 Ma (Strong et al 1978;Krogh et al 1988;Murphy et al 2008).…”

Section: Tectonic Evolution Of the Grand Manan Terranementioning

confidence: 99%

The Grand Manan Terrane of New Brunswick: Tectonostratigraphy and Relationship to the Gondwanan Margin of the Iapetus Ocean

Fyffe

2014

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Recently gathered stratigraphic and U–Pb geochronological data indicate that the pre-Triassic rocks of the Grand Manan Terrane on the eastern side of Grand Manan Island can be divided into: (1) Middle Neoproterozoic (late Cryogenian) quartzose and carbonate sedimentary sequences (The Thoroughfare and Kent Island formations); (2) a Late Neoproterozoic (early Ediacaran) volcanic-arc sequence (Ingalls Head Formation); and (3) Late Neoproterozioc (mid- Ediacaran) to earliest Cambrian (early Terreneuvian) sedimentary and volcanic-arc sequences (Great Duck Island, Flagg Cove, Ross Island, North Head, Priest Cove, and Long Pond Bay formations). A comparison to Precambrian terranes on the New Brunswick mainland (Brookville and New River terranes) and in adjacent Maine (Islesboro Terrane) suggests that the sedimentary and volcanic sequences of the Grand Manan Terrane were deposited on the continental margin of a Precambrian ocean basin that opened during the breakup of Rodinia in the Middle Neoproterozoic (Cryogenian) and closed by the Early Cambrian (Terreneuvian) with the final assembling of Gondwana. Rifting associated with the initial opening of the Paleozoic Iapetus Ocean began in the Late Neoproterozoic (late Ediacaran) and so overlapped in time with the closing of the Precambrian Gondwanan ocean. The southeastern margin of the Iapetus Ocean is defined by thick sequences of quartz-rich Cambrian sediments (within the St. Croix and Miramichi terranes of New Brunswick) that were largely derived from recycling of Precambrian passive-margin sedimentary rocks preserved in the Grand Manan and Brookville terranes of New Brunswick and in the Islesboro Terrane of Maine. These Precambrian terranes are interpreted to represent dextrally displaced basement remnants of the Gondwanan continental margin of Iapetus, consistent with the model of a two-sided Appalachian system proposed by Hank Williams in 1964 based on his work in Newfoundland.SOMMAIREDes données stratigraphiques et géochronologiques U–Pb obtenues récemment indiquent que les roches prétriasiques du terrane de Grand Manan du côté est de l’île Grand Manan peuvent être répartis en: 1) séquences sédimentaires quartzeuses et carbonatées du Néoprotérozoïque moyen (Cryogénien tardif) (formations de Thoroughfare et de Kent Island); 2) séquence d’arc volcanique du Néoprotérozoïque tardif (Édiacarien précoce) (formation d’Ingalls Head); 3) séquences sédimentaires et d’arc volcanique du Néoprotérozoïque tardif (milieu de l’Édiacarien) au tout début du Cambrien (Terreneuvien précoce) (formations de Great Duck Island, Flagg Cove, Ross Island, North Head, Priest Cove et Long Pond Bay). Une comparaison avec des terranes du Précambrien dans la partie continentale du Nouveau-Brunswick (terranes de Brookville et New River) et dans le Maine adjacent (terrane d’Islesboro) semble indiquer que les séquences sédimentaires et volcaniques du terrane de Grand Manan se sont déposées sur la marge continentale d’un bassin océanique précambrien qui s’est ouvert durant la fracturation de la Rodinia au Néoprotérozoïque moyen (Cryogénien) et s’est fermé au Cambrien précoce (Terreneuvien) avec l’assemblage final du Gondwana. La distension continentale associée à l’ouverture initiale de l’océan Iapetus au Paléozoïque a commencé au Néoprotérozoïque tardif (Édiacarien tardif) et a donc partiellement coïncidé avec la fermeture de l’océan précambrien du Gondwana. La marge sud-est de l’océan Iapetus est définie par d’épaisses séquences de sédiments cambriens riches en quartz (dans les terranes de St. Croix et de Miramichi du Nouveau-Brunswick) issus en grande partie du recyclage de roches sédimentaires de la marge continentale passive du Précambrien préservées dans les terranes de Grand Manan et de Brookville au Nouveau-Brunswick et dans le terrane d’Islesboro dans le Maine. Ces terranes précambriens sont interprétés comme la représentation de vestiges, ayant subi un déplacement dextre, du socle de la marge continentale gondwanienne de l’océan Iapetus, ce qui concorde avec le modèle d’un système appalachien à deux côtés proposé par Hank Williams en 1964 sur la base de ses travaux à Terre-Neuve.

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Section: Tectonic Evolution Of the Grand Manan Terranementioning

confidence: 99%

The Grand Manan Terrane of New Brunswick: Tectonostratigraphy and Relationship to the Gondwanan Margin of the Iapetus Ocean

Fyffe

2014

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“…On the Avalon Peninsula, the late Neoproterozoic strata comprise an apparently conformable succession, some 6±7 km thick, overlying the massive glacial deposits of the Gaskiers Formation A maximum age for the glaciogene Gaskiers Formation is constrained by a 606´8 6 3´7 Ma U-Pb zircon date from basement rocks of the Harbour Main (Krogh et al 1988). High in the Conception Group, the most richly populated fossil bed in the Mistaken Point Formation was smothered by a crystal-bearing ash layer dated at 565 6 3 Ma (Benus 1988).…”

Section: Stratigraphy Of Avalon Zonementioning

confidence: 99%

“…A maximum age for the glaciogene Gaskiers Formation is constrained by a 606´8 6 3´7 Ma U-Pb zircon date from basement rocks of the Harbour Main (Krogh et al 1988). High in the Conception Group, the most richly populated fossil bed in the Mistaken Point Formation was smothered by a crystal-bearing ash layer dated at 565 6 3 Ma (Benus 1988).…”

Section: Stratigraphy Of Avalon Zonementioning

confidence: 99%

The first named Ediacaran body fossil, Aspidella Terranovica

2000

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ABSTRACT. Aspidella terranovica Billings, 1872 was ®rst described from the late Neoproterozoic Fermeuse Formation (St. John's Group) on the Avalon Peninsula of eastern Newfoundland, approximately 1 km stratigraphically above the famous Ediacaran biota at Mistaken Point, and several kilometres below the base of the Cambrian. Aspidella has been reinterpreted perhaps more than any other Precambrian taxon, and has variously been regarded as a fossil mollusc or medusoid', a gas escape structure, a concretion, or a mechanical suction mark. Our studies indicate that Aspidella includes a wide variety of preservational morphs varying from negative hyporeliefs with a raised rim and ridges radiating from a slit (Aspidella-type preservation), to¯at discs with a central boss and sharp outer ring (Spriggia preservation), to positive hyporeliefs with concentric ornamentation (Ediacaria preservation). Specimens occur in a continuum of sizes, with preservational styles dependent on the size of the specimen and the grain size of the host lithology; the elongation of specimens is tectonic. Aspidella is con®rmed as a body fossil from observations of complex radial and concentric ornamentation, mutually deformed borders in clusters of specimens, and occurrence on the same bedding planes as certain distinctive Ediacaran taxa. Aspidella is indistinguishable from, and has priority over, several of the most common genera of late Neoproterozoic discoidal body fossils worldwide. Similar fossils from Australia are interpreted as holdfasts of frond-like organisms. The density of specimens in the Aspidella beds suggests levels of benthic biomass in the Neoproterozoic that could rival those of modern marine communities. The serial growth forms, Palaeopascichnus, Intrites, Neonereites renarius and Yelovichnus, associated with Aspidella, are interpreted as body fossils of unknown af®nities rather than trace fossils. A new, trilobed, Ediacaran body fossil, Triforillonia costellae gen. et sp. nov., is described from the Aspidella beds of the Fermeuse Formation.T H E discovery and description of Aspidella terranovica Billings, 1872 in what is now known as the Fermeuse Formation of the St. John's Group, from the Avalon Zone of eastern Newfoundland (Text-®gs 1±2), came at a time when geologists were grappling with the relatively new disciplines of stratigraphy and systematic palaeontology. The earliest references to these discoidal impressions realized their utility in establishing stratigraphical relationships on the Avalon Peninsula (Murray 1868, 1873; Billings 1872). It was another matter to explain enormous numbers of fossils of apparently soft-bodied organisms in very old strata. The fact that the Aspidella-bearing formation clearly underlay the local trilobite-bearing`Primordial' strata, with marked unconformity, added to the concern of later commentators.Despite regular reviews of the status of Aspidella (see Hofmann, 1971 and references therein, plus subsequent references by Hsu È (1972), King (1980), Landing et al. (1988), Conway Morris (19...

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“…The timing of older events remains unclear, however. At present the best estimates for the timing of Varanger ice ages come from U-Pb zircon dates on volcanic rocks that lie thousands of meters below (606 ϩ3.7/ Ϫ2.9 Ma; Krogh et al 1988;602Ϯ3 Ma;Kaye and Zartman 1980) and thousands of meters above (565 Ϯ 5 Ma; Benus 1988) inferred Varangerequivalent tillite in the Avalon terrane of Newfoundland and Massachusetts (Myrow 1995). In the absence of a chemostratigraphic framework, however, it is unclear which glaciation the Avalon tillite represents.…”

Section: Introductionmentioning

confidence: 99%