Bimodal Silurian and Lower Devonian volcanic rock assemblages in the Machias-Eastport area, Maine

Gates, Olcott; Moench, Robert H.

doi:10.3133/pp1184

Cited by 26 publications

(43 citation statements)

References 60 publications

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“…Pending further study, the opposed structural vergence shown by the Brunswick and Penobscot Bay subduction complexes, and an evolution toward strongly bimodal magmatism along the coastal belt (van Wagoner et al, 1988;Gates and Moench, 1981;Seaman et al, 1995;Ludman and Idleman, 1998) seem closely comparable to the consequences of divergent double subduction in the Lachlan fold belt of southeast Australia (Soesoo et al, 1997).…”

Section: Speculative Accretionary and Interaccretionary Eventsmentioning

confidence: 99%

“…In eastern Maine, a distal facies of the volcanic belt unconformably overlies St. Croix beds (Ludman, 1991b, references therein). Gates and Moench (1981) and others argued for an extensional non-arc setting for the coastal volcanic belt. However, hafnium, thorium, and tantalum data contained in that report suggest that the basalts are calc-alkaline (J.F.…”

Section: Coastal Volcanic Arcmentioning

confidence: 99%

“…Interstratified tholeiitic basalts and calcalkaline silicic volcanic rocks occur, for example, in the Coastal Volcanic arc (Fig. 1, CVA) and elsewhere (Gates and Moench, 1981, and references).…”

Section: Oliverian Plutonic Suitementioning

confidence: 99%

“…Although exposures preclude determination of the original terrane association, the Newbury is reasonably inferred to be the volcanic expression of calc-alkalic intermediate to granitic Silurian and Early Devonian plutonism in the Putnam-Nashoba belt (Hepburn et al, 1995, p. 361;references therein). In eastern Maine and southern New Brunswick, volcanics of the belt are a bimodal sequence of basalt, rhyolite-dacite, very sparse andesite, and granite and gabbroic plutons (van Wagoner et al, 1988;Gates and Moench, 1981;Seaman et al, 1995). In New Brunswick, the volcanic belt is represented by the Early Silurian to Early Devonian Mascarene cover sequence, which unconformably overlies rocks of Avalon to the southeast and overlaps the St. Croix terrane to the northwest (Fyffe et al, 1991, pp.…”

Section: Coastal Volcanic Arcmentioning

confidence: 99%

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Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Moench¹,

Aleinikoff²

2003

Physics and Chemistry of the Earth, Parts A/B/C

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The Ammonoosuc sequence is defined by the Middle Ordovician Ammonoosuc Volcanics near Littleton, NH, the type area, northeast to Milan, NH, and Oquossoc, ME; it also includes black slate of the Partridge Formation (C. bicornis--zone graptolites, $457 Ma). Related metamorphosed intrusives are the tonalitic Joslin Turn pluton (469 AE 2 Ma), the Cambridge Black granitic pluton (468 AE 3 Ma), and gabbro, tonalite (467 AE 4 Ma), and sheeted diabase of the Chickwolnepy intrusions. These intrusives cut lowermost Ammonoosuc (therefore >469 Ma). Probable uppermost Ammonoosuc is dated at 465 AE 6 and 461 AE 8 Ma. Successively below the Ammonoosuc are the Dead River and Hurricane Mountain Formations (flysch and melange), and the Jim Pond Formation (484 AE 5 Ma) and Boil Mountain Complex (both ophiolite), which are structurally underlain by the Neoproterozoic(?) Chain Lakes massif.The Quimby sequence is defined by the Lower Silurian(?) to Upper Ordovician Quimby Formation, composed of bimodal volcanics (443 AE 4 Ma) and sulfidic shale and graywacke that lie conformably to unconformably above the Ammmonoosuc Volcanics and Partridge Formation. Also in the Quimby sequence are several granitic to sparsely gabbroic plutons of the Highlandcroft (441-452 Ma) and Oliverian (435-456 Ma) Plutonic Suites, which intrude the Dead River, Ammonoouc and Partridge, but not the Quimby Formation.Based on faunal, paleolatitude, and isotopic data, the Ammonoosuc sequence and its correlatives and underlying sequences formed off the southern Laurentian margin, but northwest of the principal Iapetan suture, or Red Indian line. The Boil MountainJim Pond-Hurricane Mountain sequence was ramped northwestward over the Chain Lakes massif at $475 Ma, on the basal Boil Mountain surface. This obduction probably occurred slightly before obduction on the Baie Vert-Brompton surface (BBL), farther NW, over the Laurentian margin, and was followed by Dead River flysch sedimentation, which ended with the abrupt onset of Ammonoosuc-sequence arc magmatism at $470 Ma. Ammonoosuc eruptions probably ended at $460 Ma, when Iapetus closed along the Red Indian line.During a following magmatic hiatus of $3-5 m.y., now represented by portions of the Partridge Formation that overlie the Ammonoosuc Volcanics, subduction polarity reversed, and subduction resumed below the northwest-dipping Brunswick subduction complex (BSC) of New Brunswick, Canada. Quimby-sequence magmatism ($456-435 Ma) on the newly accreted Laurentian margin occurred above the BSC, whose footwall is now buried to the southeast by mainly Silurian clastic sediments of the MerrimackFredericton trough, deposited in the ''Fredericton Sea''. In Silurian to Early Devonian time, the NW-dipping BSC footwall was paired with a SE-dipping subduction zone that produced arc magmas of the Coastal Volcanic belt, built on the composite Avalon and adjacent peri-Avalonian terranes. Orogen-normal extension produced by rapid rollback of both subduction zones narrowed the Fredericton Sea, produced the Central Maine and Connecti...

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Section: Speculative Accretionary and Interaccretionary Eventsmentioning

confidence: 99%

Section: Coastal Volcanic Arcmentioning

confidence: 99%

Section: Oliverian Plutonic Suitementioning

confidence: 99%

Section: Coastal Volcanic Arcmentioning

confidence: 99%

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Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Moench¹,

Aleinikoff²

2003

Physics and Chemistry of the Earth, Parts A/B/C

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“…Based on gravity and meagre geochemical coverage, the Late Ordovician-Devonian sequences were generally considered to have developed on sialic Neoproterozoic basement in a tensional tectonic environment (e.g., Gates and Moench 1981;Thomas and Willis 1989). Currie and McNicoll (1999) mirrored this interpretation by invoking a transtensional tectonic regime related to formation and subsequent destruction by subduction of a hypothetical ocean basin to the northwest, in the Fredericton Trough (Kingsclear Group).…”

Section: G E O L O G I C a L S E T T In G H Is T O R Ic A L P E R Smentioning

confidence: 99%

Mafic intrusions on Campobello Island: implications for New Brunswick - Maine correlations

McLeod

Pickerill

Lux

2001

atgeol

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Late Ordovician through Early Devonian units of the Passamaquoddy Bay area are interpreted to represent sequences that evolved in arc and back-arc environments. The main elements of the arc are exposed on Campobeilo Island and include a predominantly felsic volcanic sequence to the northeast, a sequence of intercalated turbidite and mafic volcanic rocks to the southwest, and mafic dyke swarms throughout. Petrographic, geochemical, and 40Ar/39Ar studies of these rocks record episodic deformation and varying degrees of metamorphism up to lower amphibolite facies, and a protracted history of mafic magma injection from a similar source beginning in the Early Silurian. These features, combined with stratigraphic relationships and overall structural patterns, indicate a rapid transition from felsic-to mafic-dominated magmatism accompanied by radical changes in the depositional regime in the arc with time, and exposure of progressively deeper crustal levels towards the northeast within the arc.Review of the assignment of other units in the Passamaquoddy Bay region to major tectonostratigraphic belts north of Campobeilo Island clarifies regional correlations and provides possible additional links to Neoproterozoic basement in the area.Les unites de TOrdovicien superieur au Devonien inferieur du secteur de la baie Passamaquoddy sont interpretees comme des unites representatives de sequences ayant evolue dans des environnements d'arc et d'arriere-arc. Les principaux elements de Pare affleurent sur Pile Campobeilo et component une sequence principalement volcanofelsique au nord-est, une sequence volcanomafique/turbiditique intercalee au sud-ouest et des groupes de filons mafiques un peu partout. Des etudes petrographiques, geochimiques et 40Ar/39Ar de ces roches reinvent une deformation episodique et des degres divers de metamorphisme jusqu'au facies amphibolique inferieur, ainsi que des antecedents prolongds d'injection de magma mafique d'une source similaire a partir du Silurien inferieur. Ces p articulars, conjuguees aux relations stratigraphiques et aux configurations structurales generates, revelent une transition rapide d'un magmatisme a predominance felsique a un magmatisme a predominance mafique accompagne de changements spectaculaires dans le regime de sedimentation a Pinterieur de Parc avec le temps, ainsi qu'un affleurement de niveaux crustaux progressivement plus profonds vers le nord-est a Pintdrieur de Parc. L'examen de Paffectation des autres unites dans la region de la baie Passamaquoddy aux principals structures teconostratigraphiques au nord de Pile Campobeilo clarifie les correlations regionales et foumit des liens suppldmentaires possibles avec le socle du Proterozoi'que superieur du secteur. In t r o d u c t io nDiabase dykes and gabbroic intrusions comprise a significant portion of most Silurian sections in the Passamaquoddy Bay area of southwestern New Brunswick. Numerous older publications based on work in the 1960s and 1970s (e.g., Cumming 1966Helmstaedt 1968;Ruitenberg 1968;Donohoe 1978;Gates 196...

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Map Integration Model Applied in Site Selection

Tabesh

1992

Use of Microcomputers in Geology

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Bimodal Silurian and Lower Devonian volcanic rock assemblages in the Machias-Eastport area, Maine

Cited by 26 publications

References 60 publications

Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Mafic intrusions on Campobello Island: implications for New Brunswick - Maine correlations

Map Integration Model Applied in Site Selection

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