Accurate assessment of the petroleum potential of the Nechako Basin hinges on a comprehensive understanding of the basin architecture developed within Cretaceous strata, which represent the most prospective targets in the subsurface. Modeling the subsurface facies distribution of these Cretaceous strata requires detailed stratigraphic analysis of coeval, laterally adjacent strata exposed along the basin margins.

This three-year project will provide a detailed analysis of the Cretaceous stratigraphy of the northern Methow Basin, including the Lower Cretaceous Jackass Mountain Group (JMG), which is probably the best candidate for a major reservoir system in the subsurface of the Nechako Basin. Additional examination of other early Cretaceous sedimentary units of the south central Nechako Basin, commonly termed Skeena Group or "Skeena Assemblage" will help resolve the confusion in terminology for these early Cretaceous units, which may largely represent northern continuations of Methow Basin deposystems.

The JMG and associated strata include thick (100's m), laterally extensive (10's km) marine sandstone successions that overlie and interfinger with marine mudstones. Previous studies of the JMG and bounding successions have been primarily "first order" stratigraphic assessments commonly associated with government regional mapping projects. This study will significantly expand and supersede earlier studies and emphasize more detailed stratigraphic analysis.

This investigation will provide comprehensive sedimentologic and stratigraphic analysis of Cretaceous strata in the southern part and along the southern margin of the Nechako Basin, including detailed petrologic analysis (with porosity/permeability estimates), provenance studies (detrital mica and zircon, Nd analysis of fine-grained units, geochemistry of conglomerate clasts), biostratigraphic studies and assessment of hydrocarbon reservoir rock potential. Integration of these data sets will be the basis for a comprehensive model of basin evolution during Early Cretaceous time, which should in turn allow prediction of regional changes in facies associations into the subsurface of the Nechako Basin.

Posters and Presentations

2009: Cretaceous evolution of the Methow-Tyaughton Basin, British Columbia: A sedimentologic, geochemical, and isotopic analysis
- Mineral Exploration Roundup Poster (pdf, 3.23MB)

2008: New studies of the Lower Cretaceous sedimentary strata on the southern margin of Nechako Basin - progress and preliminary observations
- Mineral Exploration Roundup Poster (pdf, 21.0MB)

2008: Stratigraphy, Sedimentology and Hydrocarbon Reservoir Potential of the Lower Cretaceous Jackass Mountain Group, Southern Nechako Basin, Camelsfoot Range, BC - Preliminary Observations
- Mineral Exploration Roundup Poster (pdf, 38.7MB)

2008: Stratigraphy, Sedimentology and Hydrocarbon Reservoir Potential of the Lower Cretaceous Jackass Mountain Group, Chilko Lake Area, British Columbia
- Mineral Exploration Roundup Poster (pdf, 3.60MB)

2007: Stratigraphic Analysis of Cretaceous Strata Flanking the Southern Nechako Basin: Constraining basin Architecture and Reservoir Potential
- Mineral Exploration Roundup Poster (pdf, 33.7MB)

Technical Articles

2009: "Regional facies patterns in the northern Jackass Mountain Group, northern Methow Basin, southwestern British Columbia"
- Summary of Activities 2008, Paper 2009-1 p.183-192 (pdf, 5.80MB)

2008: "New studies of the Lower Cretaceous Jackass Mountain Group on the southern margin of the Nechako Basin, south-central British Columbia: progress and preliminary observations"
- Summary of Activities 2007, Paper 2008-1 p.135-144 (pdf, 9.42MB)

2007: "Stratigraphic Analysis of Cretaceous Strata Flanking the Southern Nechako Basin (Parts of NTS 092M, O; 093B), British Columbia: Constraining Basin Architecture and Reservoir Potential"
- Geological Fieldwork 2006, Paper 2007-1 p.377-380 (pdf, 6.32MB)

Final Deliverables

M.Sc. Thesis - J. Russell Goodin

Sedimentology and stratigraphy of the Lower Cretaceous Jackass Mountain group, Camelsfoot Range, British Columbia - Simon Fraser University, 2008 - Available digitally through Simon Fraser University (pdf, 20.8MB)

Abstract: The Cretaceous Jackass Mountain Group (JMG), within the Camelsfoot Range of south-central B.C., is a >2 km thick succession of marine and nonmarine volcanic-rich, feldspathic litharenite and lithic arkose sandstone, lesser mudstone, and minor conglomerate, ranging early Aptian to Cenomanian/Turonian age. The JMG was deposited in the Jura-Cretaceous Methow-Tyaughton Basin, a piggyback basin that formed atop the accreting Bridge River, Cadwallader, and Shulaps terranes, between west coast North America and impending Insular Belt terranes. It is likely that most JMG sediment was derived from first cycle weathering of nearby source rocks dominated by a mix of moderately weathered volcanic and plutonic complexes. Three facies associations were identified that essentially represents two-thousand metres of sand-rich submarine fan turbidites, delta front or prodelta deposits, and nonmarine sedimentation. Combined, the facies associations represent an overall regression in the Methow-Tyaughton Basin as accreting terranes eventually closed the basin and amalgamated it onto the continent.

M.Sc. Thesis - Catherine MacLaurin

Sedimentology, stratigraphy, and provenance of the Lower Cretaceous Jackass Mountain Group, Chilko Lake area, British Columbia, Canada - Available soon through Simon Fraser University