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TitleThe Lower Silurian Sayabec Formation in northern Gaspé: carbonate diagenesis and reservoir potential
AuthorLavoie, D; Chi, G
SourceBulletin of Canadian Petroleum Geology vol. 49, no. 2, 2001 p. 282-298,
Alt SeriesGeological Survey of Canada, Contribution Series 200089
Mediapaper; on-line; digital
File formatpdf
NTS22A; 22B/01; 22B/08; 22B/09; 22B/16; 22G/01; 22G/08; 22H/01; 22H/02; 22H/03; 22H/04; 22H/05; 22H/06; 22H/07
AreaNorthern Gaspé; Gaspésie; Gaspé Peninsula; Ruisseau Isabelle; Lac Madeleine; Rivière Madeleine
Lat/Long WENS -66.5000 -64.0000 49.5000 48.0000
Subjectsfossil fuels; sedimentology; diagenesis; carbonates; reservoir rocks; porosity; hydrothermal alteration; fracturing; calcite; brine; meteoric waters; facies; limestones; dolomites; hydrocarbons; nearshore environment; offshore areas; carbon isotopes; oxygen isotopes; stable isotope studies; fluid inclusions; petrographic analyses; depositional environment; dolomitization; stylolites; hydrocarbon migration; sea level changes; Lower Silurian; Sayabec Formation; Northern Outcrop Belt; Salinic disturbance; Acadian Gaspé Belt; Appalachian Orogen; Salinic unconformity; post-Taconian; primary porosity; secondary porosity; fracture-filling cements; pore-filling cements; carbonate ramps; dissolution; sediment infills; peritidal; neptunian dykes; microthermometry; Paleozoic; Silurian
Illustrationsgeological sketch maps; stratigraphic columns; diagrams; tables; photomicrographs; photographs; plots; histograms; charts
ProgramAppalachian Foreland and St. Lawrence Platform NATMAP Project
AbstractThe Lower Silurian Sayabec Formation represents a peritidal-dominated carbonate ramp that developed at the northern edge of the post-Taconian Gaspé successor basin. In the Late Silurian, during the Salinic disturbance, the Sayabec ramp was subaerially exposed locally. This could have lead to the formation of economically significant secondary dissolution porosity. A detailed diagenetic study of the Sayabec Formation was carried out at selected localities along the Northern Outcrop Belt in the Gaspé Peninsula, where the Salinic unconformity and hydrothermal alteration of the carbonate facies have been documented.
The diagenetic history consists of initial minor marine diagenesis (marine cements in boundstones and neptunian dykes) followed by pervasive burial diagenesis that resulted in the emplacement of various pore- and fracture-filling calcite cements, due to the mixing of basinal brines and hydrothermal fluids. Late Silurian tectonic exhumation of the lithifled carbonate ramp is recorded locally in meteoric-cement-filled fractures that were dissolution-enhanced after early burial. The significance of this event in generating porosity was relatively minor.
Preserved porosity is observed where limestone facies and calcite cements were completely replaced by hydrothermal saddle dolomite. However, the porous dolostone is of geographically limited extent. The hydrothermal event is mostly recorded in high-temperature calcite cements that occlude burial fractures.