GEOSCAN, résultats de la recherche


TitreLithogeochemical facies of Athabasca Basin clastics, Saskatchewan - the use of PCA as a reconnaissance and mapping tool
AuteurRamaekers, P; Bosman, S A; Card, C D
SourceCommission géologique du Canada, Dossier public 7790, 2016, 18 pages,
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Formatspdf; xlsx; rtf
SNRC64E; 64L; 64M; 74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P
Lat/Long OENS-112.0000 -103.0000 60.0000 57.0000
Sujetslithogéochimie; roches clastiques; faciès clastiques; faciès géochimiques; grès; tufs volcaniques; argiles; brèches; quartzarénites; gisements d'uranium; Groupe d'Athabasca ; Bassin d'Athabasca ; Formation de Manitou Falls ; géochimie; sédimentologie; Protérozoïque
Illustrationslocation maps; tables; plots
ProgrammeÉtude des gîtes d'uranium, Initiative géoscientifique ciblée (IGC-4)
Diffusé2016 04 07
Résumé(disponible en anglais seulement)
This study illustrates how Principal Component Analysis (PCA) of lithogeochemical data may be used to identify and map lithogeochemical facies using a regional-scale database of ca. 40,000 samples. This database also includes ca. 11,000 samples with enough stratigraphic data to permit this to be done in three dimensions to a rudimentary degree. The facies distribution by stratigraphy and deposystems furthers the understanding of depositional, alteration history, and ore processes of the Athabasca Basin and its high-grade unconformity-related U deposits.
PCA permits distinction and mapping of detrital and alteration facies, separating uraniferous detrital facies from those related to mineralization processes. The analysis helps to form working hypotheses about the ore systems in the basin, identify areas of further interest, as well as areas whose high U values suggest that they might be important, but which, in fact, are not involved in the mineralization processes. Uranium bound in minerals released during partial dissolution techniques contributes less than a third of the U signal in the non-mineralized sandstone. Thus, immobile U not related to alteration can mask the signal of hydrothermal U that still may be recognized by PCA. PCA also highlights potential large, but complex metal depleted zones around some of the major orebodies. If true, then the interpretation of low raw data element values or low U component scores from PCA in a regional context is as important as the interpretation of high values. Samples from above or very near mafic intrusive suites in the basin show anomalously high and low values for some elements, as well as for a number of PCA components. This suggests that the mafic intrusions generated hydrothermal systems of only limited extent.
Consistent with recent fluid-flow modelling, differences in alteration facies above and below the Wolverine Point Formation show that the unit was an aquitard. Low levels of alteration facies in the basal unit in the Athabasca Basin imply that it was an aquifer in many areas. Both these observations reinforce long-standing field observations.
Résumé(Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration qui fournit à l'industrie les connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gisements minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. À l'aide de la base de données géochimiques sur l'uranium d'Athabasca (OF7495), le présent dossier public met en lumière les variations géochimiques liées aux faciès de dépôt et d'altération régionale dans le bassin d'Athabasca afin de faciliter l'exploration de gisements d'uranium liés à des discordances.