Occurrence and regional geological setting of Paleozoic rocks on the Grand Banks of Newfoundland

King, Lewis H.; Fader, G B J; Jenkins, W. A. M.; King, E.L.

doi:10.1139/e86-052

Cited by 29 publications

(9 citation statements)

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“…The basin has a maximum thickness of 1.5 km in the vicinity of the profile, based upon the density used for the Carboniferous rocks. This thickness is compatible with the data from L. H. King et al (1986).…”

Section: Quantitative Modelssupporting

confidence: 91%

“…The gravity data in particular indicate that the Carboniferous sedimentary basin in the centre of Placentia Bay (L. H. King et al 1986) is situated above a basement block of west-dipping mafic volcanics. The basin has a maximum thickness of 1.5 km in the vicinity of the profile, based upon the density used for the Carboniferous rocks.…”

Section: Quantitative Modelsmentioning

confidence: 96%

“…Although its constitution and its extent offshore east of Newfoundland have been partially deduced by geophysical interpretation (Haworth and Lefort 1979;Jacobi and Kristoffersen 1979;Miller et al 1985), the bedrock geology of the offshore portion of the zone, south of and including Placentia and St. Mary's bays, is not well determined. The only information available is the limited sampling of the sea-bottom outcrops and shallow seismic surveys in selected areas (Lilly 1965(Lilly , 1966Fader and King 198 1 ; L. H. King et al 1986). …”

Section: Introductionmentioning

confidence: 99%

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A geophysical interpretation of the onshore and offshore geology of the southern Avalon Terrane, Newfoundland

Miller¹

1987

Can. J. Earth Sci.

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This paper presents new land and underwater gravity data for the southern portion of the Avalon Terrane of Newfoundland. These gravity data are combined with existing airborne and marine magnetic data to produce a detailed geophysical interpretation of the geology of the southern Avalon Peninsula and the adjacent portions of Placentia and St. Mary's bays.Qualitative interpretation of the geophysical data in conjunction with the known geology reveals that the major faults previously mapped only on land and inferred beneath St. Mary's Bay can be traced offshore geophysically. In addition, the previously unknown offshore limits of a small sedimentary basin in the southeast part of the area can be delineated.Quantitative modelling demonstrates that (1) Precambrian mafic to ultramafic rocks underlie the whole area, (2) thrust faulting in the St. Mary's Peninsula and elsewhere has led to the juxtaposition of Bull Arm volcanic rocks over Harbour Main volcanic rocks, and (3) the evolution of the area may be explained by a combination of earlier volcanic island and extensional models.The mapping has also revealed the presence of previously unknown northwest-southeast lineations in the geophysical patterns, which inay be related to the late wrench faulting.Le prksent article fait connaitre les nouvelles donnkes gravimktriques obtenues sur le continent et en mer pour la partie sud du terrane d'Avalon de Terre-Neuve. Ces donnkes gravirnktriques sont couplees aux donnkes de levks magnktiques akroportks et sous-marins afin de complkter llinterpr@tation gkophysique dktaillke de la gkologie de la partie sud de la pkninsule d'Avalon et des parties adjacentes des baies de Placentia et de St. Mary's.L'interprktation qualitative des donnkes gkophysiques jointes aux connaissances gkologiques de la region rkvkle que les failles majeures antkrieurement cartographikcs seulement sur le continent et extrapolkes dans la baie de St. Mary peuvent &re trackes maintenant au large gr5ce aux donnkes gkophysiques. En plus, les contours ma1 connus en mer d'un petit bassin sedimentaire dans la partie sud-est de la rkgion peuvent maintenant &re dklimitks.La modklisation quantitative dkmontre que (I) les roches mafiques i ultramafiques prkcambriennes sont sous-jacentes dans toute la rkgion, (2) les failles de chevauchement dans la peninsule de St. Mary's et ailleurs ont entraine une juxtaposition des roches volcaniques de Bull Arm surmontant les roches volcaniques d'Harbour hilain et (3) l'kvolution de la rkgion est expliquke par une combinaison de modkles d'iles volcaniques anciennes et de distention.La cartographie a aussi rkvkle la presence de linkations nord-ouest -sud-est inconnues antkrieurement dans les levks geophysiques et qui peuvent etre relikes i une faille de dkcrochement tardive.[Traduit par la rev-ue]Can.

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Section: Quantitative Modelssupporting

confidence: 91%

Section: Quantitative Modelsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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A geophysical interpretation of the onshore and offshore geology of the southern Avalon Terrane, Newfoundland

Miller¹

1987

Can. J. Earth Sci.

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“…To infer the amount of extension of the Newfoundland margin along SCREECH line 2, we must establish the crustal structure of the Grand Banks before Mesozoic rifting. Drilling and seismic reflection surveys show that basement of the northern Grand Banks largely consists of Proterozoic bedrock of the Avalon terrane [ O'Brien et al , 1983; King et al , 1986; Durling et al , 1987]. As this continental block docked during the Appalachian orogeny, it acquired a 4‐ to 8‐km‐thick sequence of Ordovician to Devonian sediments on much of the Grand Banks [ Durling et al , 1987; O'Brien et al , 1983].…”

Section: Geological Settingmentioning

confidence: 99%

Seismic velocity structure of the rifted margin of the eastern Grand Banks of Newfoundland, Canada

et al. 2006

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We present a compressional seismic velocity profile of the crust of the eastern margin of the Grand Banks of Newfoundland, Canada. This velocity model was obtained by a tomographic inversion of wide‐angle data recorded on a linear array of 24 ocean bottom seismometers (OBSs). At the landward side, we imaged a crustal thickness of 27 km in Flemish Pass and beneath Beothuk Knoll, which is thinner than the 35‐km‐thick crust of the central Grand Banks. We therefore assume that the eastern rim of the Grand Banks stretched uniformly by 25%. Farther seaward, the continental crust tapers rapidly beneath the continental slope to ∼6 km thickness. In the distal margin we find a 60‐km‐wide zone with seismic velocities between 5.0 and 6.5 km s−1 that thins to the southeast from 6 to 2 km, which we interpret as highly extended continental crust. Contrary to other seismic studies of the margins of the Grand Banks, we find seismic velocities of 8 km s−1 and higher beneath this thin crustal layer in the continent‐ocean transition. We conclude that mantle was locally emplaced at shallow levels without significant hydration from seawater or serpentinized mantle was removed along a décollement in the final stages of continental rifting. The outer edge of highly extended continental crust borders a 25‐km‐wide zone where seismic velocities increase gradually from 6.3 km s−1 just below the top of acoustic basement to 7.7 km s−1 at 5 km below basement. We interpret this area as a relatively narrow zone of exhumed and serpentinized continental mantle. Seaward, we imaged a thin and laterally heterogeneous layer with a seismic velocity that increases sharply from 5.0 km s−1 in basement ridges to 7.0 km s−1 at its base, overlying mantle velocities between 7.8 and 8.2 km s−1. We interpret this area as unroofed mantle and very thin oceanic crust that formed at an incipient, magma‐starved, ultraslow spreading ridge. A comparison of the conjugate rifted margins of the eastern Grand Banks and the Iberia Abyssal Plain show that they exhibit a similar seaward progression from continental crust to mantle to oceanic crust. This indicates that before continental breakup, rifting exhumed progressively deeper sections of the continental lithosphere on both conjugate margins. A comparison between the continent‐ocean transition of the Grand Banks and Flemish Cap shows that the final phase of continental rifting and the formation of the first oceanic crust required more time at the Grand Banks margin than at the southeastern margin of Flemish Cap.

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“…The southern half of the bay is shallow in the west, where the basement rocks at the sea floor are overlain by till in many areas. Carboniferous rocks extend part way up the centre of the bay (King et al 1986), where water depths average 200 m. Here, unpublished surveys show that bedrock is overlain by patchy till, glaciomarine silt and thick deposits of postglacial mud. The surficial geology of the southwestern entrance to the bay was described by Fader et al (1982), who mapped a series of surficial units identical to those in the Bay of Fundy (Fader et al 1977).…”

Section: Study Areasmentioning

confidence: 76%

Late Wisconsinan glacial landsystems on Atlantic Canadian shelves: New evidence from multibeam and single‐beam sonar data

Shaw¹,

Todd²,

Brushett³

et al. 2009

Boreas

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Multibeam sonar surveys in the past decade, augmented by single-beam data from the OLEX charting system, reveal landsystems on Atlantic Canadian shelves that are diagnostic of Late Wisconsinan ice-sheet dynamics. Four landsystems are described. (1) The Bay of Fundy landsystem comprises two contrasting sets of bedforms, and is interpreted as evidence of topographically controlled fast-flowing ice adjacent to slower-moving ice.(2) The German Bank landsystem off southwest Nova Scotia is comprised of glacially fluted terrain overprinted by De Geer moraines and arcuate recessional moraines. We infer that a flow of grounded glacial ice out of the Bay of Fundy was followed by steady retreat, punctuated by at least one major re-advance. (3) The Placentia Bay landsystem consists of a convergent field of streamlined landforms with superimposed De Geer moraines, overprinted in one area by flutings. We infer that this landsystem was formed in the onset zone of fast-flowing ice, and that overprinting was due to a re-advance of ice from offshore. (4) The south coast of Newfoundland landsystem, which includes arcuate, fjord-mouth moraines and a coast-parallel, fluted moraine, indicates strong topographic control on a retreating marine ice margin as it reached a fjord coastline. These submarine glacial landsystems are not inconsistent with a conceptual model showing Late Wisconsinan ice advance to shelf edges, rapid calving retreat along deepwater channels and slower retreat of ice margins grounded in shallow water. The re-advances documented two of the study areas have parallels in the Last British Ice Sheet, confirming that the reorganization of marine-based ice sheets, caused by calving in embayments, led to internally forced re-advances.

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Occurrence and regional geological setting of Paleozoic rocks on the Grand Banks of Newfoundland

Cited by 29 publications

References 0 publications

A geophysical interpretation of the onshore and offshore geology of the southern Avalon Terrane, Newfoundland

A geophysical interpretation of the onshore and offshore geology of the southern Avalon Terrane, Newfoundland

Seismic velocity structure of the rifted margin of the eastern Grand Banks of Newfoundland, Canada

Late Wisconsinan glacial landsystems on Atlantic Canadian shelves: New evidence from multibeam and single‐beam sonar data

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