Post-Taconic blueschist suture in the northern Appalachians of northern New Brunswick, Canada

Staal, Cees R. van; Ravenhurst, Casey E.; Winchester, J. A.; Roddick, J. C.; Langton, John

doi:10.1130/0091-7613(1990)018<1073:ptbsit>2.3.co;2

Cited by 62 publications

(28 citation statements)

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“…The interpreted Middle Ordovician age of the Sormany Formation is consistent with the presence of Late Arenig or younger conodonts (Nowlan, 1988) and poorly preserved brachiopods, corals, and bryozoans (Skinner, 1974) in limestone pods and shale lenses intercalated with the ocean floor basalts, and with its exposure to regional deformation and metamorphism in the Ashgill (ca. 447 Ma, van Staal et al, 1990). McLelland et al, 1993) and western Newfoundland (J.…”

Section: Implications Of Isotopic Resultsmentioning

confidence: 95%

Provenance of tectonic history of the Gander Zone in the Caledonian/Appalachian Orogen: Implications for the origin and assembly of Avalon

Staal¹,

Sullivan²,

Whalen³

1996

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

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New U-Pb zircon, Nd-Sm, and Sr isotopic data from Gander Zone basement fragments in northern New Brunswick, combined with a review of existing data, support a basement-cover relationship between the Avalonian Bras d'Or-Brookville belt and lower Paleozoic clastic rocks of the Gander Zone. Basement fragments occur as (1) large foliated and unfoliated granodiorite cobbles in a late Arenig to Llanvirn conglomerate of the Vallée Lourdes Formation of the Tetagouche Group and (2) as an allochthonous gabbro sheet (Upsalquitch gabbro), tectonically emplaced on top of the Tetagouche Group during Late Ordovician or Early Silurian thrusting.The granodiorite cobbles of the Vallée Lourdes Formation yielded late Mesoproterozoic (ca. 1.09 Ga) U-Pb zircon crystallization ages and gave an ε Nd (T) of -3.47 and a depleted mantle model age (T DM ) of 2.0 Ga. Xenocrystic zircon grains in the cobbles range in age between ca. 1.16 and 1.55 Ga. Geochemical data from a foliated granodiorite cobble suggest that the magma from which it crystallized formed by mixing of mantle-derived and older (>1.5 Ga) crustal-derived components.The Upsalquitch gabbro has a U-Pb zircon crystallization age of 543 +1/-2 Ma (earliest Cambrian) and is inferred to represent a fragment of the Gander Zone basement. Similar age igneous rocks occur in the Avalonian Bras d'Or-Brookville belt. The Upsalquitch gabbro forms the immediate base to one of the Middle Ordovician basalt suites of the Fournier Group (ca. 464 Ma), which indicates the presence of a significant hiatus. The Fournier Group was deposited in a back-arc basin that formed by splitting a late Arenig magmatic arc built on the Gander Zone. During rifting of the arc the gabbroic basement fragment was tectonically exhumed onto the sea floor by low-angle normal faulting immediately before eruption of the basalts. The gabbro's geochemistry indicates that it was mainly derived from a depleted mantle source. Xenocrystic zircons (ca. 2.6 Ga) in the Upsalquitch gabbro suggest the involvement of old Archean crust, although the presence of the latter is not reflected in the Nd-and Sr-isotopic data.The ages presented in this chapter complement detrital and xenocrystic zircon studies carried out by others in the Gander Zone of New Brunswick and Newfoundland and together indicate that basement to the Gander Zone is mainly made up of Early Cambrian (0.54-0.55 Ga), Neoproterozoic (0.6-0.8 Ga), Mesoproterozoic (1.0-1.55 Ga), and Archean rocks (2.5-2.7 Ga). This range of ages, combined with the isotopic and geochemical data, eliminates Laurentia as a possible basement to the

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Section: Implications Of Isotopic Resultsmentioning

confidence: 95%

Provenance of tectonic history of the Gander Zone in the Caledonian/Appalachian Orogen: Implications for the origin and assembly of Avalon

Staal¹,

Sullivan²,

Whalen³

1996

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

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“…Concurrent with Williams' work, evidence for latest Ordovician to Silurian, post-Taconic to pre-Acadian orogenesis was progressively growing in the Northern Appalachians (e.g. van Staal 1987van Staal , 1994van der Pluijm and van Staal 1988;Dunning et al 1990; van Staal et al 1990;West et al 1992;Cawood et al 1994;Hibbard 1994;van Staal and de Roo 1995). Following the discovery by Boucot (1962) of stratigraphic evidence for Silurian tectonism (Salinic disturbance) in central Maine, the latest Ordovician to Silurian tectonism was referred to as the Salinic orogeny by Dunning et al (1990) and Malo and Bourque (1993).…”

Section: Introductionmentioning

confidence: 82%

Time-Transgressive Salinic and Acadian Orogenesis, Magmatism and Old Red Sandstone Sedimentation in Newfoundland

Staal¹,

Zagorevski²,

McNicoll³

et al. 2014

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We propose an intimate relationship between Silurian terrestrial red bed sedimentation (Old Red Sandstone), slab breakoff-related magmatism and deformation in the Newfoundland Appalachians. Red bed sedimentation started during the Early Silurian, and records the progressive rise of the Salinic mountains in the tectonic hinterland of the orogen. The red beds were mainly deposited in molasse-style foreland basins in front of an east-propagating terminal Salinic deformation front. New U–Pb zircon dating of volcanic rocks interlayered with the Silurian red beds in key structural locations yielded ages ranging between 425 and 418 Ma, which, combined with the existing geochronological database, suggests that the sedimentary rocks are progressively younger from west to east and overstep the accreted Gondwana-derived terranes. We propose that deposition of the red beds is a good proxy for the time of cratonization of the accreted terranes. Eastward migration of the Salinic deformation front was accompanied by eastward-widening of a slab-breakoff-related asthenospheric window. The latter is interpreted to have formed due to a combination of progressive steepening of the down-going plate following entrance of the leading edge of the Gander margin and its eduction. Gander margin eduction (reversed subduction) is proposed to have been instigated by the trench migration of the Acadian coastal arc built upon the trailing edge of the Gander margin, which developed contemporaneously with the Salinic collision. The resultant thinning of the lithosphere beneath the Salinic orogen, built upon the leading edge of the Gander margin immediately prior to the onset of the Early Devonian Acadian orogeny, set the stage for generation of the widespread bloom of Acadian magmatism.SOMMAIRENous proposons qu’il y a eu une relation intime entre la sédimentation des couches rouges continentales au Silurien (vieux-grès-rouges), un magmatisme lié à une rupture de segments de croûte, et la déformation appalachienne à Terre-Neuve. La sédimentation des couches rouges qui a débuté au début du Silurien témoigne du soulèvement progressif des monts saliniques de l’arrière-pays tectonique de l’orogène. Les couches rouges se sont déposées sous forme de molasses dans des bassins d’avant-pays, à l’avant du front de déformation salinique terminale qui se déployait vers l’est. De nouvelles datations U-Pb sur zircon de roches volcaniques interstratifiées avec des couches rouges siluriennes en des lieux structurels stratégiques montrent des âges qui varient entre 425 Ma et 418 Ma, ce qui, combiné aux bases de données géochronologiques existantes permet de penser que les roches sédimentaires sont progressivement plus jeunes d’ouest en est, et qu’elles surplombent les terranes accrétés du Gondwana. Nous suggérons que les couches rouges sont de bons indicateurs temporels de la cratonisation des terranes accrétés. La migration vers l’est du front de la déformation salinique a été accompagnée par un élargissement vers l’est d’une fenêtre asthénosphérique liée à une rupture de la croûte. Cette dernière aurait été provoquée par la combinaison de l’enfoncement progressif de la plaque qui a suivi l’entrée du bord d’attaque de la marge de Gander, et son éduction. Nous proposons que l’éduction (l’inverse de la subduction) de la marge de Gander a été provoquée par la migration de la fosse tectonique côtière acadienne, induite par la migration du bord d’attaque de la marge de Gander, contemporaine de la collision salinique. L’amincissement de la lithosphère sous l’orogène salinique qui en a résulté, et qui s’est déployé au bord d’attaque de la marge de Gander juste avant l’enclenchement de l’orogénie acadienne au début du Dévonien, a préparé le terrain du déploiement à grande échelle du magmatisme acadien.

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“…Isoclinal folds and a strong penetrative axial planar schistosity were formed early during the first two deformation events (D1 and D2) [39]. Kink folds postdate the schistosity and were formed before and during the formation of the Caribou Synform [39]. A large dextral kink on the northwest limb of the Tetagouche Antiform produced the Caribou Synform (F4) [6,39].…”

Section: Deposit Geologymentioning

confidence: 99%

“…Kink folds postdate the schistosity and were formed before and during the formation of the Caribou Synform [39]. A large dextral kink on the northwest limb of the Tetagouche Antiform produced the Caribou Synform (F4) [6,39]. …”

Section: Deposit Geologymentioning

confidence: 99%

“…The Caribou deposit has been intensely deformed with associated greenschist metamorphism during multiple collisional events related to the closure of the Tetagouche-Exploits back-arc basin and incorporation of the Bathurst Supergroup into an internally imbricated accretionary complex [39]. Isoclinal folds and a strong penetrative axial planar schistosity were formed early during the first two deformation events (D1 and D2) [39].…”

Section: Deposit Geologymentioning

confidence: 99%

See 1 more Smart Citation

Analysis of Au-Ag Mineralization in the Caribou Base-Metal VMS Deposit, New Brunswick; Examination of Micro-Scale Inter- and Intra-Sulphide Distribution and Its Relation to Geometallurgy

et al. 2016

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Abstract:The Caribou Zn-Pb-Cu-Ag volcanogenic massive sulphide deposit located in northeast New Brunswick represents a significant base-metal resource in the Bathurst Mining Camp. Zinc, Pb and Cu are the primary resources that are being extracted from this deposit; however, Au and Ag are important by-products that could help offset costs. This study used mineral liberation analysis supported further by in situ laser ablation inductively-coupled plasma-mass spectrometry methods to document variations in Au and Ag distribution between and within sulphide minerals. The variations in Ag and Au distribution provide critical inputs to the optimization of mineral processing design. The greatest influence on Au recovery at Caribou is the proportion of Au hosted in arsenopyrite and pyrite; consequently, considerable Au will report to the tailings. Silver recovery at Caribou is highly affected by the proportion of Ag hosted in galena and tetrahedrite-tennantite. Proximal to the vent complex, Ag values are primarily hosted in galena, whereas further from the vent complex, Ag values are likely primarily hosted in tetrahedrite-tennantite. Galena Ag values will report mostly to the Pb concentrate, while tetrahedrite-tennantite Ag values will report to the Cu concentrate.

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Post-Taconic blueschist suture in the northern Appalachians of northern New Brunswick, Canada

Cited by 62 publications

References 0 publications

Provenance of tectonic history of the Gander Zone in the Caledonian/Appalachian Orogen: Implications for the origin and assembly of Avalon

Provenance of tectonic history of the Gander Zone in the Caledonian/Appalachian Orogen: Implications for the origin and assembly of Avalon

Time-Transgressive Salinic and Acadian Orogenesis, Magmatism and Old Red Sandstone Sedimentation in Newfoundland

Analysis of Au-Ag Mineralization in the Caribou Base-Metal VMS Deposit, New Brunswick; Examination of Micro-Scale Inter- and Intra-Sulphide Distribution and Its Relation to Geometallurgy

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