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TitleGSC bedrock mapping and stratigraphic studies of the Colville Hills, Northwest Territories
AuthorFallas, K M; MacNaughton, R B; MacLean, B C
Source43rd Annual Yellowknife Geoscience Forum - Abstracts; by Irwin, D; Normandeau, P X; Gervais, S D; 2015.
Alt SeriesEarth Sciences Sector, Contribution Series 20150411
PublisherNorthwest Territories Geological Survey
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS96K; 96L; 96M; 96N
AreaColville Hills
Lat/Long WENS-128.0000 -124.0000 68.0000 66.0000
Subjectsstratigraphy; petroleum exploration; biostratigraphy; Franklin Mountain formation; Mount Kindle formation; Delorme Group; Keele Arch; bedrock mapping; Cretaceous
ProgramMackenzie Corridor, Shield to Selwyn, GEM2: Geo-mapping for Energy and Minerals
AbstractAs a contribution to the Mackenzie Project of the Geological Survey of Canada's Geo-mapping for Energy and Minerals Program, bedrock mapping and stratigraphic studies of the Colville Hills petroleum exploration area was undertaken in July and August of 2015. Outcrops were examined for stratigraphic and structural relationships within NTS map areas 96K, 96L, 96M, and 96N. Known petroleum seeps within the area were also visited to examine their geological setting and collect samples. The aim of this work was to improve existing geological maps of the area, clarify the stratigraphic history of the region, refine the structural relationships in conjunction with available public-domain reflection-seismic data, and relate these features to the petroleum system. To improve upon reconnaissance-scale mapping by the Geological Survey of Canada in 1968, some effort was made to subdivide the Franklin Mountain and Mount Kindle formations, address lithologic variations in the Bear Rock interval ' including identifying strata possibly belonging to the Delorme Group ' and resolve the Cretaceous succession. It is hoped that samples collected for biostratigraphy will be able to confirm initial impressions from field observations. These initial impressions suggest that each of these unconformity bounded intervals is variably preserved across the study area, providing indications of different periods of deposition versus uplift and erosion related in part to the Keele Arch. Published maps based on the 1968 reconnaissance work interpreted the region's prominent topographic ridges to be underlain by elongate anticlines. Recent reflection-seismic data interpretations suggest the presence of thrust faults and/or steeper reverse faults associated with the major structures and 2015 field work has locally confirmed these relationships at surface. Efforts to subdivide stratigraphic units have also revealed additional faults in the southern part of the study area, at the northern edge of the Franklin Mountains. Tilting of Cretaceous strata on the flanks of major structures suggests that the formation of surface structures in the Colville Hills was later than the Early Cretaceous, likely as part of the development of the adjacent Franklin Mountains and Mackenzie Mountains. The Colville Hills differ, however, in that the orientation of the major structures is more variable and generally at high-angle to Cordilleran structural trends. Based on reflection-seismic evidence, this may be the result of reactivation of older normal or reverse faults in the subsurface. Petroleum seeps visited in 2015 were noted to occur in close proximity to interpreted steeply-dipping faults. Since the Devonian source-rock, the Canol Formation, is known to be absent in the Colville Hills, it is suspected that the petroleum may have migrated to surface from Cambrian Mount Clark or Mount Cap strata along the mapped faults. Samples collected in 2015 will be geochemically fingerprinted to compare with known regional petroleum sources to test this hypothesis.
Summary(Plain Language Summary, not published)
This abstract summarizes the content of a talk being given at the Yellowknife Geoscience Forum in November 2015. The talk will cover the results of 2015 field work by the GSC in the Colville Hills as part of the Mackenzie Project of the Geo-mapping for Energy and Minerals (GEM) program. The focus of the field work was on bedrock mapping, stratigraphic relationships, structural features, and the petroleum system. Reported results include improvements to the correlation and distribution of stratigraphic units and revisions to the type and number of fold and fault structures. Samples collected for fossils are expected to help confirm the age and correlation of stratigraphic units, and petroleum samples were collected from seeps to geochemically match with known petroleum sources in the region.