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TitleUpper crustal investigation of the Gulf of Saint Lawrence region, eastern Canada using ambient noise tomography
AuthorKuponiyi, A P; Kao, H; Van Staal, C; Dosso, S E; Cassidy, J F; Spence, G D
SourceJournal of Geophysical Research, Solid Earth vol. 122, issue 7, 2017 p. 5208-5227,
Alt SeriesNatural Resources Canada, Contribution Series 20170080
PublisherAmerican Geophysical Union
Mediapaper; on-line; digital
File formatpdf
ProvinceEastern offshore region
AreaGulf of St. Lawrence
Lat/Long WENS -68.0000 -58.0000 56.0000 42.0000
Subjectsgeophysics; s waves; r waves; seismic waves; seismic data; crustal studies; crustal evolution
Illustrationslocation maps; geophysical images; graphs; seismic reflection profiles
ProgramShale Gas - induced seismicity, Environmental Geoscience
AbstractWe studied the 3-D shear wave velocity (Vs) structure in the region of the Gulf of St. Lawrence and adjacent onshore areas to 20 km depth by inverting Rayleigh-wave dispersion extracted from the vertical components of continuous ambient seismic noise waveforms. The GSL and the adjacent land areas were divided into three broad zones based on their Vs characteristics. In the northwest, the Grenville Province (i.e., the exposed edge of predominantly Middle Proterozoic Laurentian crust) is dominated by high-Vs, except for well-known anorthosite sites, which are characterized by relatively lower Vs. In contrast, the central segment of the GSL region corresponds to a belt with generally low-Vs at upper crustal levels. In the southeastern part of the GSL, prominent low velocities in the uppermost crust are found to coincide with locations of subsidiary basins of the Canadian Maritime Basin, while higher Vs characterize the accreted Appalachian terranes where they are exposed on land. The Grenville Province is wedged out at depth by the Red Indian Line, which is the suture between composite Laurentia and peri-Godwanan Ganderia in the Canadian Appalachians. The geometry and Vs characteristics of the south-easternmost peri-Gondwanan terranes of Avalonia and Meguma, suggest that they may be fully or partially structurally overlying a basement with distinct seismic characteristics, which could be a vestige of the West-African craton that was under-thrust beneath composite Laurentia during the terminal Alleghenian continent-continent collision. In the middle of the GSL, the 3-D geometry of the Canadian Maritimes sedimentary basins overlying the Appalachian terranes shows that the depth to the top of basement is in excess of 8 km.
Summary(Plain Language Summary, not published)
Continuous seismic waveforms recorded at all available seismograph stations in the Gulf of Saint Lawrence (GSL) region are analyzed to derive the three-dimensional shear wave (Vs) velocity structure of the sedimentary basins and upper crust. A generally low velocity zone separates high Vs structures of the Grenville Province to the north and the southeastern Appalachian terranes. The results of this study provide unprecedented constraints on the overall geometry of the major sedimentary basins in the GSL and the accreted terranes responsible for the formation of the Appalachian mountain belt.