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TitreUpper Jurassic - Lower Cretaceous lithofacies, detrital petrology and diagenesis of the Louisbourg J-47 well, Scotian Shelf
AuteurPe-Piper, G; Brown, E; Piper, D J W; DeCoste, A
SourceCommission géologique du Canada, Dossier public 6693, 2010, 277 pages, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
ProvinceRégion extracotière de l'est
Lat/Long OENS-59.0000 -58.0000 45.0000 44.0000
Sujetslithofaciès; pétrographie; roches sédimentaires; milieu sédimentaire; antecedents de sedimentation; sedimentation; diagenèse; caractéristiques structurales; failles; biostratigraphie; historique de l'enfouissement; maturation thermique; analyses structurales; caractéristiques structurales; déformation; sables; graviers; paléogéographie; descriptions de carottes; analyse de carottes; carottes; carottes de sédiment marin; Formation de Chaswood ; sédimentologie; stratigraphie; pétrologie ignée et métamorphique; Mésozoïque; Crétacé; Jurassique
Illustrationslocation maps; photographs; logs; images
ProgrammeGéoscience en mer, Analyse de bassin et ressources géoscientifiques
Diffusé2010 11 04
Résumé(disponible en anglais seulement)
The sedimentary petrography of the Lower Cretaceous and Upper Jurassic in the Louisbourg J-47 well has been studied from five conventional cores. The core was logged sedimentologically and sampled for petrographic thin sections. Detrital minerals diagnostic of provenance were analysed by electron microprobe and their chemical composition compared with elsewhere in the Scotian basin and with bedrock in the hinterland. Diagenetic minerals were characterized by backscattered electron images of thin sections, and electron microprobe analysis.
Conventional core shows three facies associations. 1) In the Verrill Canyon Formation, thick blocky mass-transport deposits predominate. (2) In the Upper MicMac Formation, the cored succession is similar to coeval rocks assigned to the Lower Missisauga Formation at Venture and Thebaud. Delta-front turbidites pass up into tidal channel sands in parasequences that are characteristic of shelf-margin deltas with adequate accommodation. (3) In the Middle Missisauga Formation, a delta-top succession is present in which tidal flat and thin shelf sediments predominate.
Some 60-70% of the detrital quartz is interpreted to be derived from granitoid rocks. Feldspars more abundant in the Missisauga Formation (predominantly K-feldspar) than in the Mic Mac Formation (predominantly plagioclase). Feldspar abundance, lithic clasts, and the chemistry of detrital spinels and tourmaline is similar to that found in the Peskowesk A-99 well. Compared to the Lower Missisauga Formation of the Venture and Thebaud fields, chlorite rims on detrital grains are strikingly absent in the coeval and sedimentologically similar Mic Mac Formation sandstones at Louisbourg. Quartz overgrowths are present in almost all sandstones, which also contain early diagenetic kaolinite, likely formed by meteoric water diagenesis. The Fe-silicate precursor of chlorite rims is likely oxidised and destroyed under conditions of meteoric water diagenesis. This study has also shown the occurrence of diagenetic apatite and sphalerite. It suggests that care must be taken in selecting apatite grains for fission track thermochronological analysis. Sphalerite suggests the availability of hot, saline formation waters.