Late Ordovician platform foundering, its paleoceanography and burial, as preserved in separate (eastern Michigan Basin, Ottawa Embayment) basins, southern Ontario

Abstract

Comparison of litho-, bio-, and chemostratigraphy in two cores from the northeastern margin of the Michigan Basin (Manitoulin Island) and from within the Ottawa Embayment (eastern Ontario) identifies interbasinal differences of Late Ordovician platform foundering linked to Taconic orogenesis. Graptolite biostratigraphy defines an east-to-west younging (late Edenian to early Maysvillian) of platform burial. A regional unconformity likely caps the platform succession. In both basins, an increased supply of mafic material appears during the final stages of platform collapse, with the accumulation of organic-rich (<8%), petroliferous shales (Collingwood Member -Michigan Basin; Eastview Member -Ottawa Embayment). Both units preserve evidence for deposition coincident with increased dysoxic to possible anoxic bottom-water conditions, but the Collingwood Member accumulated under a relatively stable paleoceanographic environment. Rhythmic interbedding with platform limestone in eastern Ontario, combined with evidence for fluctuating paleoproductivity, suggests the depositional environment of the Eastview Member was more sensitive to higher order controls affiliated with tectonic, oceanographic, and (or) sea level variation. Such interbasinal differences likely reflect a greater rate of subsidence in the Manitoulin region transforming platform sedimentation to a distal ramp facies. In eastern Ontario, a lesser rate of subsidence maintained a shallower water, but open margin, setting. Burial of the Upper Ordovician platform, as preserved in eastern Ontario, occurred during peak dysoxic conditions, with deposition of a hemipelagic facies (Billings Formation) that marks the peak supply of clay-size mafic-derived sediment. Bottom-water ventilation occurred only with appearance of abundant Taconic-derived distal turbidites. An equivalent hemipelagic facies appears to be absent from the Manitoulin region. However, equivalent resedimented deposits are represented by the Blue Mountain Formation.Résumé : Des comparaisons de la litho-, bio-et chimiostratigraphie dans deux carottes provenant de la bordure du bassin de Michigan (île Manitoulin) et de la baie d'Ottawa (est de l'Ontario) identifient les différences entre les bassins de l'effondrement de plate-forme à l'Ordovicien tardif relié à l'orogenèse taconique. La biostratigraphie de graptolites définit un rajeunissement de l'est vers l'ouest (Edenien tardif à Maysvillien précoce) de l'enfouissement de la plate-forme. Une discordance régionale chapeaute sans doute la succession de la plate-forme. Dans les deux bassins, l'approvisionnement en matériaux mafiques croît durant les stages finals de l'effondrement de la plate-forme avec l'accumulation de shales pétrolifères, riches en matière organique (<8 %) (membre Collingwood -bassin de Michigan; membre Eastview -baie d'Ottawa). Les deux unités ont conservé des évidences d'une déposition qui coïncide avec des conditions d'eau de fond de plus en plus dyxosiques à possiblement anoxiques; cependant, le membre Collingwood s'est accumulé...

Surface and subsurface signatures of gas seepage in the St. Lawrence Estuary (Canada): Significance to hydrocarbon exploration

“…2) comprises basal siliciclastics which are overlain by a thick accumulation of shallow-to ultimately deep-marine carbonates deposited on a ramp affected by syn-sedimentary extensional faults (upper Chazy, Black River and Trenton groups and correlative units, Lavoie, 1994Lavoie, , 1995Salad Hersi and Lavoie, 2001;Lemieux et al, 2003). The carbonate sedimentation was shut down with the progressive encroachment of deep marine shales (Late Ordovician Utica Shales), and overlying Late Ordovician Taconian flysch and final molasse derived from the Appalachian highlands (Sanford, 1993;Lavoie, 1994;Sharma et al, 2003).…”

Evolution of faulting and paleo-stress field within the Ottawa graben, Canada

“…In the Ottawa area, the Paleozoic sedimentary rocks consist mainly of a sequence of Middle to Upper Ordovician carbonate and siliclastic units belonging to formations of the Ottawa Group (Uyeno, 1974;Sanford, 1993;Salad Hersi and Dix, 1999;Sharma et al, 2003). These formations include the Pamelia, Lowville, Chaumont, Bobcaygeon, Verulam and Lindsay (Williams and Rae, 1983;Williams et al, 1984;Salad Hersi and Dix, 1999;Sharma et al, 2003).…”

“…These formations include the Pamelia, Lowville, Chaumont, Bobcaygeon, Verulam and Lindsay (Williams and Rae, 1983;Williams et al, 1984;Salad Hersi and Dix, 1999;Sharma et al, 2003). In many cases, lithologic boundaries correspond to mapped faults.…”

“…In many cases, lithologic boundaries correspond to mapped faults. The Ottawa Group succession, which represents peritidal facies to open shelf or ramp facies (Sanford, 1993;Salad Hersi and Dix, 1999;Sharma et al, 2003), is overlain by a succession of deep water to shallow water basinal siliclastics (Billings, Carlsbad, Queenston formations) that is linked to basin fill of the Taconic foreland basin (Sanford, 1993;Sharma et al, 2003).…”

Late Ordovician (Chatfieldian) catastrophic volcanism and abrupt carbonate platform-interior subsidence: A tectonic link across a Taconian foreland basin (Quebec Embayment) due to inherited crustal weakness

“…This association youngs to the west, through the Ottawa Embayment and into the Canadian craton interior (Dix et al, 2007). Subsequent deepwater dysoxic basinal sediments were succeeded by a westward progradational, basin-fill, flysch succession leading to marginal marine conditions of the Queenston Formation (Sharma et al, 2003;Sharma and Dix, 2004). This latter unit extends across most of the distal foreland basin (Sanford, 1993;Lehmann et al, 1995).…”