Tectonics and basin deformation in the Cabot Strait area and implications for the late Paleozoic development of the Appalacians in the St. Lawrence Promontory

• Main Author: Langdon, George S.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1996
• Subjects: Cabot; Magdalen; Newfoundland; Red Island
• Online Access: https://research.library.mun.ca/7192/; https://research.library.mun.ca/7192/1/Langdon_GeorgeS.pdf; https://research.library.mun.ca/7192/3/Langdon_GeorgeS.pdf

The Cabot Strait lies astride the Cabot Fault system at the eastern extent of the Magdalen Basin, a pull-apart structure which was the depocentre of the regional Maritimes successor basin during the late Devonian to early Permian development of the Canadian Appalachians. Under the Cabot Strait two linear grabens parallel the major fault trends and preserve up to 6 km of Devonian to Carboniferous sedimentary rocks. -- In Part I of this study these strata have been mapped using conventional reflection seismic data, with support from potential field and onshore geological data. A series of major dextral strike-slip faults, including the Cape Ray Fault, the Hollow-St. George's Bay Fault, and the Red Island Fault parallel the regional trend, and define a wrench borderland geometry with the Cabot Fault as the master fault. The Cape Ray Fault is shown to have played a role in middle to late Devonian basin formation as well as Carboniferous deformation, while the others were active only in the Carboniferous. Four unconformities yield timing of movement along the faults and allow correlations to be made with regional deformation. Classic wrench-related features such as restraining bends, flower structures and inversion profiles are present in the Cabot Strait-Bay St. George area. -- In Part II, the middle Devonian and later modification of the orogen at the St. Lawrence Promontory is examined through a series of crustal profiles, terrane configuration sketches, and paleogeographic reconstructions. Data pertaining to the Salinic and Acadian events are compiled, and evidence is presented for the development of the preHorton/Horton basins as extensional collapse features associated with the overthickening of the crust at the collision of two promontories. Overstepping, mainly post-Tournaisian basin development is seen primarily as a consequence of dextral strike-slip. Both of the above processes were enhanced and overprinted in Newfoundland by tectonic ejection of crustal blocks away from the St. Lawrence Promontory. ...