Structural elements of the Magdalen Basin, Gulf of St. Lawrence, from seismic reflection data

Durling, P.; Marillier, F.

doi:10.4095/134281

Cited by 10 publications

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“…A northwest-southeast seismic reflection profile from offshore west Cape Breton island shows a largely undeformed sedimentary sequence, of Devonian-Lower Permian age, that encompasses the Horton-Pictou groups (Durling & Marillier 1993) (Fig. 4).…”

Section: Offshore West Cape Breton Islandmentioning

confidence: 98%

“…1). Seismic imaging indicates up to 10-12 km of normal displacement of Carboniferous units along the Hollow fault (Durling & Marillier 1993Langdon & Hall 1994). However, sedimentological (Yeo & Ruixiang 1987) and kinematic analysis (St. Jean et al 1993) on nearby onshore exposures of the Hollow fault in Nova Scotia appear to indicate that strike-slip movements have also occurred in the southern part of fault.…”

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confidence: 99%

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Displacement transfer and forced folding in the Maritimes basin of Nova Scotia, eastern Canada

Keller

Lynch

1999

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Field and seismic data in northern Nova Scotia, eastern Canada, demonstrate that displacement transfer from steep basement faulting to bedding-parallel detachment is necessary in the development of forced folds. Lateral translation of the strata above horsted and down-dropped blocks generates a monoclinal structure which, as the faults are kinematically linked, evolves in a manner similar to fault-bend folds in thrust-and-fold belts. In the case of partial transfer of displacement a breached drape syncline is developed. The breached syncline is characterized by steep upturned beds against the fault that truncates them. In the Nova Scotia example the detachment horizon is located at the base of a Visean evaporitic sequence, and is exposed in the study area showing shearing structures within the evaporites. Brittle fault rock types (gouge and cataclasite) and meso-to microstructures were formed, including stretching lineation, principal schistosity plane and secondary shear planes, as well as intrafolial to upright asymmetrical folds. The regionally extensive weak evaporitic layer was remarkably effective in transferring displacement between the two faults, with mechanical decoupling of the strata above the evaporitic detachment being observed in the horsted block 70 km away from the steep basement fault. Moreover, displacement was also transferred as much as 40 km onto the down-dropped block at the frontal part of the system. Forced (drape) folds develop by flexure of cover rocks (usually sediments) above an underlying dip-slip fault, with the cover rocks being deformed into a broad monoclinal structure.

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Section: Offshore West Cape Breton Islandmentioning

confidence: 98%

mentioning

confidence: 99%

Displacement transfer and forced folding in the Maritimes basin of Nova Scotia, eastern Canada

Keller

Lynch

1999

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“…Subsequent authors (e.g., Hyde et al, 1988;MacInnes and White, 2004;Waldron, 2004;Waldron et al, 2007;Murphy et al, 2011) have documented signifi cant strike-slip motion during deposition of various parts of the Maritimes Basin fi ll. Recently, Gibling et al (2008) compared the tectonic development of the Maritimes Basin with that of the eastern Mediterranean, and Hibbard and Waldron (2009) have suggested that subsidence in the Maritimes Basin was related to substantial (~250 km) dextral strike-slip motion throughout the Appalachians, which reactivated a promontory-reentrant system in the early Paleozoic Laurentian continental margin (Thomas, 1977(Thomas, , 1991 Lawrence, Grand Banks, and Cabot Strait (e.g., Durling and Marillier, 1993;Langdon and Hall, 1993;Brown, 1998;Pascucci et al, 1999). Diapirs imaged in shallow, offshore seismic lines from the Gulf of St. Lawrence can be traced to coastal exposures in western Cape Breton; drag zones adjacent to these diapirs were described by Alsop et al (2000).…”

Section: Maritimes Basin Tectonicsmentioning

confidence: 99%

Evaporite tectonics and the late Paleozoic stratigraphic development of the Cumberland basin, Appalachians of Atlantic Canada

Waldron

Rygel

Gibling

et al. 2013

Geological Society of America Bulletin

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The Cumberland basin is part of the large and deep Maritimes Basin of Atlantic Canada, interpreted to have developed at tropical latitudes in a tectonic environment of dextral strike slip. The predominantly Mississippian-Pennsylvanian basin fi ll includes a thick succession of Viséan evaporites of the Windsor Group. An overlying clastic succession includes, in the coal-bearing Cumberland Group, fossil forests with upright trees, preserved at the Joggins Fossil Cliffs United Nations Educational, Scientifi c, and Cultural Organization (UNESCO) World Heritage Site. Analysis of two-dimensional seismic profi les demonstrates that accommodation for the successions overlying the evaporites was provided by salt expulsion, which led to the development of broad open synclines separated by narrow isoclinal anticlines cored by salt. In the western part of the basin (Athol syncline), evaporites remained largely undisturbed until the Pennsylvanian, when their rapid expulsion accommodated accumulation of the thick Joggins succession. In the eastern part of the basin (Tatamagouche syncline), evaporite withdrawal began in the Viséan and continued during Serpukhovian time, providing accommodation for symmetric and wedge-shaped minibasins fi lled by Windsor and overlying Mabou Group strata. Only a small volume of evaporites remained to be expelled during Pennsylvanian thrusting along the southern basin margin; as a result, the Cumberland Group is relatively thin. To the north, the Black River, Wallace, and Pugwash synclines developed as minibasins having a character intermediate between the Athol and Tatamagouche synclines. Many of the halokinetic structures in the Cumberland basin are similar to those on salt-bearing passive continental margins. However, the tectonic environment in narrow fault-bounded basins encouraged vertical, rather than horizontal movement of salt and overlying sediments, and has produced characteristic inequant, oval minibasin geometries. These features may be characteristic of salt tectonics in strike-slip basins. Salt expulsion has strongly infl uenced the distribution of hydrocarbons and other resources in the basin.

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“…fault dips SE with a graben low to the south intersected by cross-cutting detachment faults or dextral shears. Howie (1988) and Durling and Marillier (1993) showed the Hollow Fault to be more steeply dipping, with the Cape Breton Highlands horst coming up in the southeast and the Magdalen Basin going down. None of the sections are in the immediate area but what appears to be important is the change from a simple fault system west to northwest of Cape Breton Island to a complex wrench system in the Cabot Strait area.…”

Section: Bedrock and Surfi Cial Geologymentioning

confidence: 99%

“…The rocks involved are the Horton, Windsor, and Mabou groups lying on an unknown pre-Horton Group basement. To the west and north to north- east lies an area of extensive salt structures of Windsor age (Howie 1988;Durling and Marillier 1993) whereas to the immediate east and northeast, all three groups occur without salt tectonics, in a zone of detached faults between the northeaststriking Hollow Fault Zone and the Cabot Fault Zone (Aspy and Wilkie Brook Faults of Fig. 4).…”

Section: Bedrock and Surfi Cial Geologymentioning

confidence: 99%

Carbonate blocks found in muddy sediment off Cape Breton Island, Nova Scotia: pieces of small authigenic carbonate mounds and vents related to hydrocarbon seeps?

Wallace

Harrington

Cook

2006

atgeol

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Carbonate blocks brought up from the seafl oor during drag fi shing in a small restricted area offshore northern Cape Breton Island are irregularly shaped and range in size from 6 cm 3 to >1 m 3 . They have smooth to "clinkery", dendritic, or "popcorn-surface" structures, can be layered to massive, and are porous. Many are highly porous and/or eroded. They contain fi ne-grained siliciclastic material (mud to granule sized) with minor amounts of bioclasts cemented by calcite. Three blocks have vent structures and some have pores lined by fi ne-grained sparite. Seismic lines in the vicinity of the discovery area show acoustic turbidity, bright spots interpreted to be hydrocarbon seeps, diaper-like structures, and columnar sediment disturbances that reach to bedrock. Outside the immediate area, pock marks occur on the sediment surface. Carbon isotope values from shelly material cemented in the blocks range from δ 13 13 C = -9.41 to -35.27 ‰ PDB (Pee Dee Belemnite) with an algae encrustation or bacterial mat yielding -61.38 ‰ PDB. From the isotopic analysis and the seismic interpretation we are confi dent that these blocks are pieces of carbonate mounds and vents formed by methanogenesis of hydrocarbon from slow seeps on the seafl oor, the hydrocarbon originating either within the recent sediment and/or from bedrock, most likely the latter. The ecology of these mounds has not been studied and needs further work in this area of active commercial fi shing. RÉSUMÉLes blocs de roches carbonatées repêchées du fond de la mer par des chalutiers dans un petit secteur à accès restreint au large, au nord de l'île du Cap-Breton, sont d'apparence irrégulière et leur taille varie entre 6 cm 3 et plus de 1 m 3 . Ils sont de texture lisse à « scoriacée », sont de nature dendritique et présentent une surface de « maïs éclaté »; les blocs peuvent être stratifi és ou d'apparence massive, et ils sont poreux. Un bon nombre des blocs sont très poreux ou érodés, ou les deux. Ils contiennent du matériau silicoclastique à grain fi n (entre la boue et les granules), ainsi que de petites quantités de bioclastes à cimentation calcitique. Trois blocs présentent une structure à orifi ces, tandis que d'autres ont des pores recouverts de sparite à grain fi n. Le profi l sismique dans les environs de la découverte indiquent une turbidité acoustique, et présentent des zones claires dont l'interprétation donne à penser qu'il s'agit de suintements d'hydrocarbures, à structure stratiforme, ainsi que des perturbations de sédiments prismatiques qui atteignent le substratum rocheux. À une certaine distance de la découverte, on note des marques de rigoles sur la surface sédimentaire. Les valeurs des isotopes de carbone tirées des matières coquillières cimentées dans les blocs varient entre δ 13 13 C = -9.41 et -35.27 ‰ PDB (bélemnites de la formation Pee Dee), et s'accompagnent d'une incrustation algale ou d'une matte bactérienne d'une valeur de -61.38 ‰ PDB. À la lumière de l'analyse isotopique et de l'interprétation sismique, nous sommes relativ...

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Structural elements of the Magdalen Basin, Gulf of St. Lawrence, from seismic reflection data

Cited by 10 publications

References 0 publications

Displacement transfer and forced folding in the Maritimes basin of Nova Scotia, eastern Canada

Displacement transfer and forced folding in the Maritimes basin of Nova Scotia, eastern Canada

Evaporite tectonics and the late Paleozoic stratigraphic development of the Cumberland basin, Appalachians of Atlantic Canada

Carbonate blocks found in muddy sediment off Cape Breton Island, Nova Scotia: pieces of small authigenic carbonate mounds and vents related to hydrocarbon seeps?

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