scholarly journals Provenance and paleogeography of post-Middle Ordovician, pre-Devonian sedimentary basins on the Gander composite terrane, eastern and east-central Maine: implications for Silurian tectonics in the northern Appalachians

2017 ◽  
Vol 53 ◽  
pp. 063-085 ◽  
Author(s):  
Allan Ludman ◽  
John T. Hopeck ◽  
Henry N. Berry IV
Keyword(s):  
Sedimentary Basins ◽  
Late Ordovician ◽  
The West ◽  
East Central ◽  
Early Devonian ◽  
Middle Ordovician ◽  
Regional Correlation ◽  
Orogenic Wedge ◽  
Connecticut Valley ◽  
Seismic Reflection Profiles

Recent mapping in eastern and east-central Maine addresses long-standing regional correlation issues and permits reconstruction of post-Middle Ordovician, pre-Devonian paleogeography of sedimentary basins on the Ganderian composite terrane. Two major Late Ordovician-Silurian depocenters are recognized in eastern Maine and western New Brunswick separated by an emergent Miramichi terrane: the Fredericton trough to the southeast and a single basin comprising the Central Maine and Aroostook-Matapedia sequences to the northwest. This Central Maine/Aroostook-Matapedia (CMAM) basin received sediment from both the Miramichi highland to the east and highlands and islands to the west, including the pre-Late Ordovician Boundary Mountains, Munsungun-Pennington, and Weeksboro-Lunksoos terranes. Lithofacies in the Fredericton trough are truncated and telescoped by faulting along its flanks but suggest a similar basin that received sediment from highlands to the west (Miramichi) and east (St. Croix).Deposition ended in the Fredericton trough following burial and deformation in the Late Silurian, but continued in the CMAM basin until Early Devonian Acadian folding. A westward-migrating Acadian orogenic wedge provided a single eastern source of sediment for the composite CMAM basin after the Salinic/Early Acadian event, replacing the earlier, more local sources. The CMAM, Fredericton, and Connecticut Valley-Gaspé depocenters were active immediately following the Taconian orogeny and probably formed during extension related to post-Taconian plate adjustments. These basins thus predate Acadian foreland sedimentation.Structural analysis and seismic reflection profiles indicate a greater degree of post-depositional crustal shortening than previously interpreted. Late Acadian and post-Acadian strike-slip faulting on the Norumbega and Central Maine Boundary fault systems distorted basin geometries but did not disturb paleogeographic components drastically.

The Ordovician brachiopod genus Bimuria from the eastern Klamath Mountains, northern California

1990 ◽  
Vol 64 (2) ◽  
pp. 200-213 ◽  
Author(s):  
A. W. Potter
Keyword(s):  
Northern Ireland ◽  
Late Ordovician ◽  
Yukon Territory ◽  
Preliminary Survey ◽  
Northern California ◽  
Klamath Mountains ◽  
The West ◽  
East Central ◽  
Middle Ordovician ◽  
Southwestern Siberia

The genus Bimuria Ulrich and Cooper, 1942, is a biogeographically important member of middle and late Ordovician brachiopod faunas of the Callahan–Gazelle area in the eastern Klamath Mountains of northern California. In middle Ordovician deposits the genus is widespread and ranges from Nevada in the west to southwestern Siberia in the east; however, in late Ordovician beds it was previously known only in Sweden and Northern Ireland. In addition to the northern California occurrence reported here, new late Ordovician occurrences are also noted in east-central Alaska–Yukon Territory and Northwest Territories. Three species of Bimuria are described, including the new species, B. californiensis.A preliminary survey of species described in the literature suggests that the ratio of the length of the dorsal adductor field to the length of the elongate area in the brachial valve decreases from middle to late Ordovician species, and thus may be of biostratigraphic value.

Évolution paléogéographique de la marge nord-ouest de l'Afrique du Cambrien à la fin du Carbonifère (du Maroc au Libéria)

1991 ◽  
Vol 28 (7) ◽  
pp. 1121-1130 ◽  
Author(s):  
Michel Villeneuve ◽  
Jean-Jacques Cornée
Keyword(s):  
West African ◽  
The West ◽  
Lower Paleozoic ◽  
West African Craton ◽  
Middle Cambrian ◽  
Early Devonian ◽  
Middle Ordovician ◽  
The North ◽  
Marine Platform ◽  
General Regression

Paleogeographic reconstructions of Paleozoic time are presented for the northwest margin of the West-African Craton. An extensional regime and a marine transgression were dominant during the Early Cambrian. During the Middle Cambrian, the Rokélides orogen was responsible for the sea regression to the south, while the proto-Atlantic opening was active to the north of the Reguibat shield. A large stable marine platform was present during Early and Middle Ordovician. A general regression and the formation of the West-African Inlandsis took place during the Late Ordovician. During Silurian time, this sea transgressed over most of the African platform. Incipient Hercynian deformations during the Early Devonian produced horsts and grabens in Morocco. At the end of the Devonian and the beginning of the Carboniferous, the sea was restricted to isolated basins and tectonic trenches. Collision between West Africa and North America during the Late Carboniferous transformed the Lower Paleozoic margin into an Hercynian orogenic belt, whose structure is controlled by the presence of crustal blocks, generated as early as the Cambrian, and probably reflecting, in turn, older Panafrican zones of weakness. [Translated by the Journal]

The Antrim–Galway Line: a resolution of the Highland Border Fault enigma of the Caledonides of Britain and Ireland

1995 ◽  
Vol 132 (2) ◽  
pp. 171-184 ◽  
Author(s):  
P. D. Ryan ◽  
N. J. Soper ◽  
D. B. Snyder ◽  
R. W. England ◽  
D. H. W. Hutton
Keyword(s):  
Deep Structure ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Late Ordovician ◽  
Magnetic Data ◽  
The South ◽  
Early Devonian ◽  
Border Fault ◽  
Western Ireland

AbstractThe westward continuation of the Highland Border fault of Scotland (HBFZ) into Ireland is problematic. It is widely thought to follow a pronounced magnetic and gravity lineament, the Fair Head-Clew Bay Line (FCL). The advantage of this interpretation is that it places all the Ordovician ophiolitic complexes and associated sedimentary basins to the south of the FCL, which would represent the contact between Laurentia and the outboard terranes. Its main shortcomings are that both the deep structure and timing of strike-slip are different on the HBFZ and FCL. In Ireland the FCL is a north-dipping feature that can be traced to the Moho on BIRPS profiles, while the HBFZ has no such signature. Terrane amalgamation in western Ireland was completed by the late Ordovician, while in Scotland the Midland Valley terrane did not finally dock until the early Devonian. These considerations suggest that in western Ireland a branch of the HBFZ exists, which was active in post-Ordovician time and must lie south of Connemara. An examination of Irish geological, geophysical and image-processed magnetic data shows that a profound lineament can be traced from Antrim to Galway Bay (the Antrim–Galway Line). Stitching plutons date movement on it as pre-405 Ma. We propose that the Antrim–Galway Line represents the continuation of the Scottish HBFZ, while the FCL is a preserved Ordovician splay of the HBFZ system whose northdipping geometry is a product of Ordovician collapse of the orogen in western Ireland.

Basin development and inversion at the Appalachian structural front, Port au Port Peninsula, western Newfoundland Appalachians

1993 ◽  
Vol 30 (9) ◽  
pp. 1759-1772 ◽  
Author(s):  
John W. F. Waldron ◽  
Glen S. Stockmal ◽  
Randolph E. Corney ◽  
Sheila R. Stenzel
Keyword(s):  
Foreland Basin ◽  
Fault Scarp ◽  
Late Ordovician ◽  
The West ◽  
Western Basin ◽  
Middle Ordovician ◽  
Platform Carbonates ◽  
Palinspastic Restoration ◽  
And Inversion ◽  
Basin Boundaries

In the Humber Zone of the Newfoundland Appalachians, Cambro-Ordovician shelf and foreland basin successions are affected by Middle Ordovician (Taconian orogeny) and Devonian (Acadian orogeny) deformation. On Port au Port Peninsula the presence of the Late Ordovician to Late Silurian Long Point – Clam Bank succession allows these episodes to be separated. The Taconian foreland basin stratigraphy on Port au Port Peninsula is highly variable. On the west coast, platform carbonates are overlain by megaconglomerates of the Cape Cormorant Formation, which record progressive exposure of 1 km of the platform succession. The conglomerates are restricted to a narrow zone, consistent with derivation from a fault scarp originally immediately west of the outcrops (in palinspastic restoration). Farther east, at Victors Brook, the Cape Cormorant Formation is absent, but the overlying, almost undeformed Goose Tickle Group contains conglomerate derived both from the upper part of the platform succession and from the Taconian Humber Arm Allochthon. Southeast of Victors Brook, the top of the platform is overlain directly by scaly shales and mélange of the Humber Arm Allochthon, which includes deformed equivalents of the foreland basin succession. The distribution of conglomeratic units, the presence and configuration of faults, and the preservation of the Goose Tickle Group in the Victors Brook area imply that a fault-bounded basin developed in advance of the Humber Arm Allochthon during the Taconian orogeny. This basin is interpreted to have resulted from flexural extension of North American lithosphere. The close spatial coincidence between later Acadian structures and the Taconian basin boundaries implies that the basin-bounding faults were reactivated as thrusts and reverse faults, and that the basin underwent inversion during Acadian thrusting. The western basin-bounding fault, modified by the development of a "short cut" thrust, developed into the present-day Round Head thrust.

The location of the Iapetus Ocean suture in Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 488-495 ◽  
Author(s):  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Lower Devonian ◽  
New World ◽  
Late Ordovician ◽  
Calc Alkaline ◽  
The West ◽  
Early Devonian ◽  
Iapetus Ocean ◽  
Lower Palaeozoic ◽  
First Time ◽  
Avalon Peninsula

Brachiopod and trilobite faunal distributions indicate that the Iapetus Ocean was still wide enough to inhibit migration in the Middle and Late Ordovician. The presence of Silurian and Lower Devonian calc-alkaline rocks suggests that ocean crust was still being subducted long after the end of the Ordovician and that the Iapetus Ocean did not finally close in Newfoundland until the Acadian Orogeny. The Reach Fault divides successions containing different Lower Palaeozoic faunas; to the west, typical North American faunas occur in New World Island (Cobb's Arm Limestone), while to the east the rocks of the Gander region appear to have been attached to the Avalon Peninsula, with its European Lower Palaeozoic faunas, since the Early Ordovician. It is concluded that the Reach Fault marks the suture where the Iapetus Ocean closed at the end of the Early Devonian. This line probably extends across Newfoundland to the south of Buchans, and links up with the Cape Ray Fault in the southwest of the island. An Ordovician fauna from the Davidsville Group of the Gander area is illustrated for the first time; it is not clearly definitive of any faunal province.

Mid-Paleozoic thrusting at the Appalachian deformation front: Port au Port Peninsula, western Newfoundland

1991 ◽  
Vol 28 (12) ◽  
pp. 1992-2002 ◽  
Author(s):  
John W. F. Waldron ◽  
Glen S. Stockmal
Keyword(s):  
Carbonate Platform ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Western Boundary ◽  
Seismic Profiles ◽  
The West ◽  
Deformation Front ◽  
Middle Ordovician ◽  
Triangle Zone ◽  
Map Scale

Structures exposed on Port au Port Peninsula in western Newfoundland record the nature of the Appalachian deformation front, which forms the western boundary of the Humber tectono-stratigraphic zone. The major structures affect the Late Ordovician to Late Silurian Long Point – Clam Bank succession, but not the unconformably overlying Carboniferous rocks; they are probably of Devonian age.At the west coast of the peninsula, Long Point and Clam Bank strata are affected by both east-vergent and west-vergent structures. The basal surface of the succession is interpreted as an east-vergent thrust, forming the upper detachment of a "triangle zone," and correlates with a similarly located contact seen in offshore multichannel seismic profiles. Within the succession, east-vergent deformation zones locally duplicate the stratigraphy. West-vergent structures, including a map-scale overturned fold north of Round Head mountain, are probably younger.Farther south, Middle Ordovician foreland basin sediments are also affected by east-vergent thrusts, which have been variably rotated by west-vergent folds. In the underlying Cambrian–Ordovician platform carbonate succession, east-vergent thrusts duplicate the stratigraphy.These structures are related to telescoping of the carbonate platform and the overlying Humber Arm Allochthon during Devonian westward wedging of the structural triangle zone beneath the Long Point – Clam Bank succession. The platform succession must therefore be allochthonous, and the Humber Arm Allochthon has been transported to the west of its Late Ordovician position.

The tectonics and depositional history of the Ordovician and Silurian rocks of Notre Dame Bay, Newfoundland

1985 ◽  
Vol 22 (4) ◽  
pp. 607-618 ◽  
Author(s):  
R. J. Arnott ◽  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Strike Slip ◽  
Late Ordovician ◽  
Island Arc ◽  
The West ◽  
Depositional History ◽  
Middle Ordovician ◽  
The North ◽  
Lower Ordovician ◽  
History Of ◽  
Ophiolitic Rocks

In the Notre Dame Bay region, ophiolitic rocks underlie a thick sequence of Lower Ordovician volcanic-arc rocks to the north of the Lobster Cove – Chanceport Fault. Neither this fault nor the Lukes Arm – Sops Head Fault shows evidence of very large strike-slip movements, as parts of the same arc, together with much arc-derived detritus, straddle both faults. Towards the east, this arc-derived detritus becomes more distal in aspect and passes laterally into the Dunnage Mélange. During the Middle Ordovician Epoch (late Llandeilo and early Caradoc), most areas show a marked decrease in volcanic activity and in the amount of coarse detritus deposited. Coarse turbidites reappear, at different times in different areas, during the Late Ordovician. These are related to several fault-bounded basins and to movements on the Lukes Arm – Sops Head Fault. Many of these faults, particularly in the east, are marked by olistostromes, several of which can be dated by fossils as Late Ordovician and Early Silurian. The whole region, between the Reach Fault on the east and the Baie Verte – Brompton Line on the west, has a stratigraphic unity. If it has been moved by strike slip relative to the Long Range, then any such fault must lie to the west of the Baie Verte – Brompton Line. The interpretation of an Early Ordovician island arc moving above an easterly directed subduction zone is in accord with both the geochemical and palaeontological evidence. The Notre Dame Bay region may have been converted into a transform-dominated margin in the Late Ordovician and Early Silurian in a manner analogous to the oblique slip tectonic regimes of the Californian and New Zealand margins during the Tertiary, with a precursor of the Reach Fault marking the edge of the continent after the Notre Dame island arc had collided with North America.

Tectonic evolution and significance of Silurian – Early Devonian hinterland-directed deformation in the internal Humber zone of the southern Quebec Appalachians

2003 ◽  
Vol 40 (2) ◽  
pp. 255-268 ◽  
Author(s):  
Sébastien Castonguay ◽  
Alain Tremblay
Keyword(s):  
New England ◽  
Tectonic Evolution ◽  
Normal Faults ◽  
Early Devonian ◽  
Middle Ordovician ◽  
Tectonic History ◽  
History Of ◽  
Connecticut Valley ◽  
Laurentian Margin ◽  
Nappe Emplacement

In the southern Quebec Appalachians, the early tectonic history of the Laurentian margin (Humber zone) comprises foreland-propagating, northwest-directed thrust faulting, nappe emplacement, and regional prograde metamorphism in response to the obduction of large ophiolitic nappes during the Taconian orogeny. In the internal Humber zone, this event is dated at 462 ± 3 Ma (late Middle Ordovician), which is interpreted to represent the timing of near-peak Taconian metamorphism. Superimposed hinterland-directed structures are accompanied by retrograde metamorphism and consist of back thrusts and normal faults, which respectively delimit the northwestern and southeastern limbs of the Sutton and Notre-Dame mountains anticlinoria, both salient structures of the internal Humber zone of southern Quebec. Geochronologic data on the timing of hinterland-directed deformation vary from 431 to 411 Ma. Two tectonic models are presented and discussed, which may account for the Silurian – Early Devonian evolution of the Laurentian margin: (1) back thrusting and syn- to post-compressional crustal extension in response to the tectonic wedging of basement-cored duplexes inducing delamination of supracrustal rocks; (2) tectonic exhumation of the internal Humber zone by extensional collapse. Evidence for Silurian – Early Devonian extensional tectonism in the Humber zone provides the basement infrastructures necessary for the creation and the onset of sedimentation in the Gaspé Belt basins (e.g., Connecticut Valley – Gaspé synclinorium). Several structural, metamorphic features in the internal Humber zone of the northwestern New England Appalachians yield analogous characteristics with those of southern Quebec and may have shared a similar Silurian – Early Devonian tectonic evolution.

New recumbent echinoderm genera from the Bois d'Arc Formation: Lower Devonian (Lochkovian) of Coal County, Oklahoma

2007 ◽  
Vol 81 (6) ◽  
pp. 1486-1493 ◽  
Author(s):  
Ronald L. Parsley ◽  
Colin D. Sumrall
Keyword(s):  
Great Britain ◽  
West Virginia ◽  
North American ◽  
Lower Devonian ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Early Devonian ◽  
Middle Ordovician

An echinoderm fauna from the Lower Devonian (Lochkovian) Cravatt Member of the Bois d'Arc Formation near Clarita, Oklahoma, has yielded specimens of recumbent, essentially bilaterally symmetrical taxa which are similar to Ordovician genera but absent or sparsely represented in Silurian strata. Claritacarpus smithi n. gen. and sp., is a dendrocystitid homoiostele with morphology similar to the Late Ordovician Dendrocystoides Jaekel, 1918; the anomalocystitid stylophoran Victoriacystis aff. holmesorum Ruta and Jell, 1999 shows strong affinities to Victoriacystis holmesorum Ruta and Jell, 1999, Humevale Formation, of Victoria, Australia; and the pleurocystitid rhombiferan, Turgidacystis graffhami n. gen. and sp., has close affinities to the Middle Ordovician Coopericystis Parsley, 1970 of West Virginia and Henicocystis Jell, 1983 of Victoria, Australia. Claritacarpus and Turgidacystis are North American range extensions for homoiosteles and pleurocystitids, respectively, being previously unknown from rocks younger than Upper Ordovician. Globally, Silurian homoiosteles and pleurocystitids are unknown although both occur in the Lower Devonian of Germany and Australia; additionally, Early Devonian pleurocystitids are known from Great Britain and Bohemia. These genera illustrate a pseudoextinction pattern suggesting a significant unsampled Silurian “homalozoan” and pleurocystitid history.

Diachronous supracrustal extension in an intraplate setting and the origin of the Connecticut Valley–Gaspé and Merrimack troughs, northern Appalachians

2005 ◽  
Vol 142 (1) ◽  
pp. 7-22 ◽  
Author(s):  
ALAIN TREMBLAY ◽  
NICOLAS PINET
Keyword(s):  
New England ◽  
Lower Crust ◽  
Tectonic Setting ◽  
Regional Scale ◽  
Sedimentary Basins ◽  
Contact Metamorphism ◽  
Crustal Extension ◽  
Early Devonian ◽  
Connecticut Valley ◽  
Metamorphic Terranes

In the Appalachians of mainland Canada and New England, Silurian/Early Devonian rocks are preserved in the Connecticut Valley–Gaspé and Merrimack troughs, and rest unconformably or in fault contact with older rocks belonging to Laurentia and to Gander/Avalon, respectively. The Silurian/Early Devonian rocks consist of marine clastic deposits with subordinate carbonates, lava flows and terrestrial deposits. The origin of these sedimentary basins is still poorly understood. Metamorphic ages and structures in the Laurentian margin, major unconformities and syn-sedimentary normal faulting in both troughs argue for significant crustal extension during deposition. The Connecticut Valley–Gaspé and Merrimack troughs are separated by inliers of pre-Ordovician to Ordovician rocks which we interpret as Silurian basement highs that would have been buried in Devonian times to form a composite sedimentary basin. Volcanic rocks are widely distributed in time and space in both basins, and are mostly subalkaline within-plate tholeiites, which is consistent with a tectonic setting involving crustal extension rather than with subduction. Granitic plutons are abundant in the Merrimack trough and attest to high temperatures at mid-crustal levels. It is suggested that crustal extension was responsible for the formation of both basins and that heating of the lower crust in the Merrimack trough during the Silurian was the result of synorogenic collapse likely triggered by delamination at the Laurentia–Medial New England boundary. Delamination of the subducted slab and the upwelling of the asthenosphere would have caused (1) isostatic uplift and formation of basement highs, (2) magmatism in the lower crust and regional-scale contact metamorphism in the upper crust, and (3) collapse of metamorphic terranes and the formation of subsiding sedimentary basins.

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