Open File Report 1998-02

Author(s) Date 1997-12-31

A reconnaissance field and geochemical program was completed in the Kakwa/Wapiti map area, which is located between the municipalities of Grande Prairie and Grande cache (1:250 000 map sheet NTS 83L), to provide baseline data and as a preliminary evaluation of the metallic mineral and kimberlite or lamproite potential.

A stream sediment heavy mineral study collected and analyzed 60 stream sediment heavy mineral concentrate samples for potential diamond indicator minerals from various bedrock and surficial geology domains. A total of 133 possible diamond indicator grains were micro-probed; and 35 of the 60 sites sampled reported diamond indicators including: chrome pyrope garnet (G9); eclogitic garnets (G3-calcic almandines and G5-magnesium); high chrome grossular garnets; chrome diopside; ilmenite; and chromite. At least six areas with anomalous values were delineated, particularly in the northeast quadrant, which drains the Cutbank River plateau. The abundance of diamond indicators are likely sourced from within Alberta and may originate either from a local bedrock volcanic source, or the result of a glacial 'deposition' of sediments from the central regions of the province, or from both.

A bentonite geochemistry study may provide a quick and inexpensive view of the provenance under which airfall pyroclastics may have formed, and to determine if the bentonite could be used to identify local kimberlitic volcanism. A total 0f 8 bentonite samples were collected in the map area, from bentonitic layers ranging in thickness from 2.0 cm and 63 cm, and analyzed for their major and trace elements. None showed a relative geochemical abundance pattern comparable to the average worldwide kimberlite or lamproite, and therefore, are likely not derived from an ultramafic source. The overall geochemical signature from rare earth element and trace element data closely duplicates the geochemical pattern for that of the average intermediate-felsic to felsic igneous rock.

A metallic minerals study collected a total of 90 bedrock samples, ranging in age from the from the Jurassic-Lower Cretaceous Nikanassin Formation to the Upper Cretaceous-Early Tertiary Coalspur Formation. Lithologies represented include: shale (36); siltstone (12); sandstone (17); conglomerate (6); bone bed (3); and bentonite (8). The results of the geochemical analysis yield anomalous trace metal values against the average concentration of crustal sedimentary rocks, and against background geochemical data established by this study. The study area represents a favourable environment for the emplacement of: sedimentary exhalative sulphides (Sedex); sedimentary Ni sulphides; stratabound sandstone U and Pb; sediment-hosted stratiform Cu; epithermal (Carling-type) Au; and placer concentrations. This contention is supported by the association of the following factors: a tectonically active sedimentary basin; magmatic activity; stratigraphic distribution of chemical sediments such as Ba; sandstones with permeability contrasts such as shale beds; reductants including coal zones; presence of phosphates; and evaporite deposits.

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Eccles, D.R., Dufresne, M.B. and Lywood, P. (1998): Diamond and metallic mineral potential of the Kakwa/Wapiti area, west-central Alberta; Alberta Energy and Utilities Board, EUB/AGS Open File Report 1998-02, 173 p.