Foreland Sequence Framework Within and Outside of a Cratonic-scale Fault System: Preliminary Analysis of the Roles of Tectonics and Eustasy from the Ottawa Embayment, Central Canada

Abstract

Abstract

The Ottawa Embayment in eastern Ontario preserves a Middle to Upper Ordovician foreland-interior succession, representing the local Tippecanoe I cratonic sequence. The embayment is bordered on three sides by Precambrian highlands, and is underlain by a reactivated paleo-aborted rift system, the Ottawa-Bonnechere graben, initiated in the late Precambrian and reactivated local and regionally through periods of the Phanerozoic.

The foreland platform succession, represented by sedimentary rocks intercalated with altered volcanic ash deposits, preserves four facies successions, in ascending order: 1) peritidal dolostone-shale 2) siliciclastic estuarine to marine 3) restricted subtidal muddy carbonate and 4) a deepening upward restricted to open-shelf. These stages of platform development document net transgression coincident with Laurentian-wide flooding by the Late Ordovician.

We present a preliminary analysis of the significance of these lithostratigraphic boundaries in the context of sequence stratigraphic models, in a foreland basin that is subject to potential changing subsidence rates relative to sediment supply and eustasy. Prominent shale-sandstone or -carbonate contacts, represent abrupt and regionally significant transgressions but whether these are tectonic or eustatic remains the purpose of this study.

The database is the core and outcrop in eastern Ontario and SW Quebec: mapping key stratigraphic-lithologic transitions; with emphasis on the Black River-Trenton boundary. Mineralogical and Geochemical analysis will be carried out on the samples. PetroMod software will use GSC #1 Russell core to model the foreland succession maturation and fluid-flow. Local vs regional flooding and shallowing events will be identified, to establish match/mismatch timing of stratigraphic events in the basin with structural events in the Taconic Orogen. Evaluate which, if any, sequence stratigraphic model best suits evolution of the foreland succession in the Ottawa Embayment.

This research will provide an understanding, with specifics to eastern Laurentia and the Taconic orogeny, on the significance of the shale stratigraphy that characterizes the lower foreland succession; define matches/mismatches with extra-basinal tectonic, depositional, and eustatic events, to determine local, regional and global controls on stratigraphy. Develop a craton-interior foreland basin maturation model and determine the significance for gas exploitation of shale in the foreland succession.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016