--> Abstract: Thermal Maturity Discontinuity Between Devonian and Cretaceous Strata, Central Mackenzie Valley, Northwest Territories, Canada, by L. D. Stasiuk, D. R. Issler, and M. G. Fowler; #90039 (2005)

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Thermal Maturity Discontinuity Between Devonian and Cretaceous Strata, Central Mackenzie Valley, Northwest Territories, Canada

L. D. Stasiuk1, D. R. Issler2, and M. G. Fowler3
1 Natural Resources Canada, Calgary, AB
2 GSC- Calgary, Calgary, AB
3 Natural Resources Canada, Calgary

The Central Mackenzie Valley Corridor, Northwest Territories, Canada, is considered to have important ‘frontier petroleum potential'. A major unconformity occurs in the region, spanning the Root Basin and Keele Tectonic Zone to the overlying foreland basin succession, between Upper Devonian (~ 375 Ma) and Lower to Upper Cretaceous (~ 110 to 95 Ma) rocks. A critical constraint on modeling the timing of petroleum generation relative to early and late hydrothermal events, tectonics (e.g. Mesozoic-Cenozoic Cordilleran orogeny) and structural trap development is defining the degree of thermal maturity discontinuity across this boundary. Previous studies (Rock Eval and %Ro analysis) conducted in late 1980's concluded that such a discontinuity only existed in the Root Basin to the south. A re-evaluation of previously analyzed Lower Devonian to Paleocene strata from older wells along with new data from more recent exploration wells and from outcrop samples suggests that the discontinuity appears to always exists but varies in magnitude. Reflectance of vitrinite and solid primary source rock bitumen, VIS fluorescence analysis of sporinite and alginite organic matter and Tmax from Rock Eval pyrolysis indicate that the discontinuous increase in thermal maturity ranges from ~ 0.20 to 0.80 %Ro vitrinite. Interpretation of maturity parameter data is complicated by the overwhelming contribution of recycled organic matter (inc. bi to tri-macerite coal particles) to total organic carbon contents in Albian to Lower Paleocene strata and rare contemporaneous vitrinite throughout Middle Devonian to Tertiary sediments, except for Maastrichtian to Paleocene lignite to sub-bituminous coals.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005