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TitleInsights on timing of hydrocarbon generation and history of orogenic unroofing gained from palynological age determination of reworked sediments in Upper Cretaceous strata of the Mackenzie Valley, Northwestern Canada
AuthorBell, K M; Hadlari, T
SourceGeological Society of America, Abstracts With Programs vol. 46, no. 6, 2014 p. 163
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140287
PublisherGeological Society of America
MeetingGSA Annual Meeting; Vancouver; CA; October 19-22, 2014
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS85E; 95G; 95H; 95I; 95J; 95N; 95O; 96C; 96D; 96E; 96F; 106H; 106I; 106J; 106M; 106N; 106O; 107B
AreaMackenzie Valley
Lat/Long WENS-136.0000 -118.0000 69.2500 61.0000
Subjectseconomic geology; fossil fuels; sedimentology; structural geology; petroleum exploration; thermal maturation; oil; oil shales; oil geochemistry; petroleum generation; hydrocarbon generation; orogenies; Carboniferous; Cretaceous; Devonian; Paleozoic
ProgramShale-hosted petroleum ressource assessment, Geoscience for New Energy Supply (GNES)
AbstractCanada's energy future will be moving north, necessitating the evaluation of unconventional petroleum potential in the Mackenzie Valley. An established geologic framework is critical for successful resource assessment. The Mackenzie Valley is filled with palynomorph bearing Upper Cretaceous strata of the Trevor (Cenomanian-Turonian), Slater River (Cenomanian-Coniacian), Little Bear (Santonian-Campanian) and East Fork (Campanian-Maastrichtian) formations. Palynomorph biostratigraphy in conjunction with seismic and well log data offers a potential solution by the accurate definition of sediment age enabling lateral correlation of petroleum bearing rock units, which is essential to developing a robust geologic framework. Additionally, the maturation of organic matter in Upper Cretaceous rocks of the Mackenzie Valley, as indicated by Rock-Eval pyrolysis (Tmax), provides constraints on potential oil generation. Existing data indicate that either Cretaceous strata generated hydrocarbons in the Paleogene or that Cretaceous strata are actually immature with extensive recycling and high Tmax values derived from reworked organic material. The origin of these Tmax data has huge implications for the oil and gas potential in the region as it determines the timing of hydrocarbon generation. The objectives of this study are to determine the best subsurface correlation model as well as the age and extent of sediment recycling using relative changes in the quantity of reworked palynomorphs as a proxy. Preliminary results indicate that there is extensive Paleozoic reworking in the uppermost Cretaceous strata of this well. Therefore, the high Tmax values were likely produced from reworked organic material rather than generated by in situ organic material. The age distribution of recycled palynomophs suggest that orogenic unroofing involved the reworking of Carboniferous to Cretaceous source strata into the Little Bear Formation and the reworking of Devonian to Cretaceous source strata into the East Fork Formation. The implications of this study for organic geochemistry and thermal maturity will provide insight on the timing of hydrocarbon generation. Insights on the history of orogenic unroofing may contribute to future regional tectonic studies.
Summary(Plain Language Summary, not published)
This work examined pollen that was recycled from older rocks before being deposited in Cretaceous strata of the Central Mackenzie Valley for two purposes: 1) to reconcile organic thermal maturity data with radiogenic thermal history data by showing how the organic readings were in fact inherited from older strata and therefore misleading; 2) by determining the age of the recycled pollen we could infer the age of the rocks that were being eroded in the mountains at the time of deposition, in the Cretaceous, which helps to define how much the mountains were uplifted at that time.