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TitleUsing palynology to test seismic correlations and determine the age of reworked sediments in Upper Cretaceous strata of the Mackenzie Valley, Northwest Territories
AuthorBell, K M; Hadlari, T
Source4th International Paleontological Congress, abstract volume; 2014 p. 889
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140288
Meeting4th International Paleontological Congress; Mendoza; AR; September 28 - October 3, 2014
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
AreaMackenzie Valley
Subjectsfossil fuels; paleontology; geophysics; palynology; palynological analyses; seismic interpretations; palynomorphs; biostratigraphy; Mesozoic; Cretaceous
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 (Albian-Cenomanian), Slater River (Albian-Coniacian), Little Bear (Santonian-Campanian) and East Fork (Campanian-Maastrichtian) formations. In this region, seismic and well log data allow for multiple complex correlations of Upper Cretaceous strata. Palynomorph biostratigraphy 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. If high resolution palynomorph biostratigraphy is successful, then it will aid in constraining the age of syndepositional structures. 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 1) test the potential seismic correlations, thereby determining the best subsurface correlation model, 2) develop a profile of precise stratigraphic ages of the Little Bear Formation and determine the location of unconformities in order to constrain the ages of syndepositional structures and 3) determine the age and extent of reworking using relative changes in the quantity of reworked palynomorphs as a proxy.
Seventy samples from the Sah Cho L-71 exploration well, spanning strata of the Slater River, Little Bear and East Fork formations, are currently available for palynological analysis. This well was selected for stratigraphic and geographic coverage and its potential as a palynostratigraphic reference section. Preliminary results indicate that there is extensive Devonian, Carboniferous and Permian/Early Triassic 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 implications of this study for organic geochemistry and thermal maturity will provide insight on the timing of hydrocarbon generation, and the age determinations will show the timing of structural trap development, which is critical for resource assessment.
Summary(Plain Language Summary, not published)
There are dramatic differences between various subsurface correlations that have used well log and seismic data in the subsurface of the Central Mackenzie Valley. We used pollen from well samples to test those correlations, the most important impact is to help date the development of structures in the subsurface that might have acted as hydrocarbon traps.