Mesozoic-Cenozoic Geology of the Eastern Margin of the Grand Banks and Its Relation to Galicia Bank

Grant, A C; Jansa, L. F.; McAlpine, K D; Edwards, Anthony

doi:10.2973/odp.proc.sr.103.173.1988

Cited by 13 publications

(20 citation statements)

References 22 publications

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“…In the Jeanne d'Arc Basin the sediments fine upwards, which Grant et al (1988) interpreted as indicating peneplanation of the source area and, by inference, continued decline of crustal extension that would lead to elevation of the sources.…”

Section: Valanginian-hauterivian (Sequence 5)mentioning

confidence: 99%

“…After this time, extension shifted to the northern margin of the Grand Banks (e.g. Orphan Basin) where it was associated with opening of the Labrador Sea (Enachescu 1988;Grant et al 1988). …”

Section: Mesozoic Riftingmentioning

confidence: 99%

“…On the Newfoundland margin, time-stratigraphic equivalents of sequence 6 appear in the deep sedimentary basins of the Grand Banks (Grant et al 1988;Tankard & Welsink 1988;Balkwill & Legall 1989) and extend seawards into basins beneath the continental slope. These rocks are mostly shalessandstones with interbedded limestones, and they reflect rapid fill that kept pace with fault-controlled basin subsidence.…”

Section: Tithonian -Berriasian (Sequence 6)mentioning

confidence: 99%

“…A major unconformity was eroded across the southern Grand Banks during the Early Cretaceous in response to deformation and doming associated with the Avalon uplift (e.g. Grant et al 1988), and it is likely that coarse clastics shed from this region help to account for the strong reflectivity in at least the central to southern Newfoundland Basin. Off Iberia the Aptian event (orange reflection) is locally strong, but it generally has lower amplitude than off Newfoundland and it seldom masks underlying structure except where debris has been shed from peridotite ridges (Figs 6a & 14).…”

Section: Barremian-aptian (Sequence 4 and A)mentioning

confidence: 99%

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Breakup of the Newfoundland–Iberia rift

2007

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The Newfoundland-Iberia rift is considered to be a type example of a non-volcanic rift. Key features of the conjugate margins are transition zones (TZs) that lie between clearly continental crust and presumed normal (Penrose-type) oceanic crust that appears up to 150-180 km farther seaward. Basement ridges drilled in the Iberia TZ consist of exhumed, serpentinized peridotite of continental affinity, consistent with seismic refraction studies. Although the boundaries between continental crust and the TZs can be defined with relative confidence, there are major questions about the position and nature of the change from rifting to normal sea-floor spreading at the seaward edges of the TZs. Notably, drilling of presumed oceanic crust in the young M-series anomalies (,M5) has recovered serpentinized peridotite, and this basement experienced major extension up to approximately 15 million years after it was emplaced. In addition, existing interpretations place the 'breakup unconformity' (normally associated with the separation of continental crust and simultaneous formation of oceanic crust) near the Aptian-Albian boundary, which is also some 15 million years younger than the oldest proposed oceanic crust (anomaly M5-M3) in the rift.To investigate and potentially resolve these conflicts, we analysed the tectonic history and deep (pre-Cenomanian) stratigraphy of the rift using seismic reflection profiles and drilling results. Rifting occurred in two main phases (Late Triassic-earliest Jurassic and Late Jurassic-Early Cretaceous). The first phase formed continental rift basins without significant thinning of continental crust. The second phase led to continental breakup, with extension concentrated in three episodes that culminated near the end of Berriasian, Hauterivian and Aptian time. The first two episodes appear to correlate with separation of continental crust in the southern and northern parts of the rift, respectively, suggesting that the rift opened from south to north in a two-step process. The third episode persisted through Barremian and Aptian time. We suggest that during this period there was continued exhumation of subcontinental mantle lithosphere at the plate boundary, and that elevated in-plane tensile stress throughout the rift caused intraplate extension, primarily within the exhumed mantle. This rifting may have been interrupted for a time during the Barremian when melt was introduced from the southern edge of the rift by plume magmatism that formed the Southeast Newfoundland Ridge and J Anomaly Ridge, and the conjugate Madeira-Tore Rise. We propose that the rising asthenosphere breached the subcontinental mantle lithosphere in latest Aptian-earliest Albian time, initiating sea-floor spreading. This resulted in relaxation of in-plane tensile stress (i.e. a pulse of relative compression) that caused internal plate deformation and enhanced mass wasting. This 'Aptian event' produced a strong, rift-wide reflection that is unconformably onlapped by post-rift sediments that were deposited as a stable sea-fl...

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Section: Valanginian-hauterivian (Sequence 5)mentioning

confidence: 99%

Section: Mesozoic Riftingmentioning

confidence: 99%

Section: Tithonian -Berriasian (Sequence 6)mentioning

confidence: 99%

Section: Barremian-aptian (Sequence 4 and A)mentioning

confidence: 99%

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Breakup of the Newfoundland–Iberia rift

2007

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“…The area of the Avalon Uplift and its flanks in the southern Grand Banks is about 5 x 10 4 km 2 ( Fig. 1 and Grant et al, 1988), requiring the erosion of an average of 1100 m of bedrock from that region simply to account for the Albian-Cenomanian succession in the Newfoundland Basin. Considerably more denudation must have occurred to supply (Karner and Shillington, 2005) and localized tectonic inversion (Karner et al, 1992).…”

Section: The Avalon Upliftmentioning

confidence: 99%

Detrital sources and sediment delivery to the early post-rift (Albian-Cenomanian) Newfoundland Basin east of the Grand Banks: results from ODP Leg 210

Hiscott

Marsaglia

Wilson

et al. 2007

Bulletin of Canadian Petroleum Geology

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The young narrow arm of the Atlantic Ocean that separated Newfoundland from Iberia in the Albian-Cenomanian accumulated a thick succession of muddy gravity flow deposits that were recovered by drilling at Ocean Drilling Program Site 1276 off the Grand Banks of Newfoundland. The sediment thickness and sand content are somewhat surprising given the number of contemporaneous shelf and slope basins that would have acted as traps for detritus shed from the Newfoundland margin. A set of individual studies was undertaken to trace the source of this detritus and to test hypotheses that the material might have been derived, in part, from the east (Iberia), the north (Flemish Cap and northern rift extensions), and/or from various sources to the west (Grand Banks, Interior Newfoundland, Avalon Uplift). By synthesizing seismic data, paleocurrent data from gravity flow deposits, sediment composition (sand detrital modes, clay mineralogy) and detrital mica ages we conclude that the likely source of the Albian-Cenomanian sediment was the Avalon Uplift, situated in the southern Grand Banks. Key pieces of evidence that lead us to this result are: thinning of the sediment package towards the north and thickening towards the southwest, the paleocurrent directions apparently suggesting a southwesterly source, the low proportion of potassium feldspar in the sandstones, and the lack of palygorskite in the shales as compared to Iberian-sourced successions. The apparent inconsistency of detrital mica ages from these deposits, suggesting an Iberian (Hercynian) source with age 270-340 Ma, is attributed to the localization of rifting along a Paleozoic continental suture zone, the Hercynian Front. This tectonic front separates distinctly different geologic units (domains) on the conjugate margins. Such a suture would have generated a significant peripheral foreland basin across the now-submerged shelf regions of Newfoundland allowing transfer of sediment from the Iberian to the Newfoundland domains. Upon Mesozoic rifting and uplift, these mica-bearing sediments from the foreland basin succession could have been reworked and shed eastward into the nascent Atlantic Ocean basin at ODP Site 1276. Alternatively, Hercynian metamorphism and deformation might have extended onto what is now the southeastern Grand Banks, so that young detrital micas could have been derived directly from the Avalon Uplift. Results from this work are relevant to an assessment of sandstone distribution in parts of the Salar Basin and the expected diagenetic overprint for sandy reservoir facies.

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