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TitreIndicator mineralogy of kimberlite boulders from eskers in the Kirkland Lake and Lake Timiskaming areas, Ontario, Canada
AuteurKjarsgaard, I M; McClenaghan, M B; Kjarsgaard, B A; Heaman, L M
SourceSelected papers from the Eighth International Kimberlite Conference, volume 2, the J. Barry Hawthorne volume; par Mitchell, R H (éd.); Grutter, H S (éd.); Heaman, L M (éd.); Scott Smith, B H (éd.); Stachel, T (éd.); Lithos vol. 77, issue 1-4, 2004 p. 705-731,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2003218
ÉditeurElsevier BV
RéunionEighth International Kimberlite Conference; Victoria, British Columbia; CA; juin 22-27th, 2003
Documentpublication en série
Mediapapier; en ligne; numérique
Référence reliéeCette publication est reliée Kjarsgaard, I; McClenaghan, B; Kjarsgaard, B; Heaman, L; (2003). Mineralogy of kimberlite boulders from eskers in the Kirkland Lake and Lake Timiskaming areas, north-eastern Ontario, Canada, 8th International Kimberlite Conference: extended abstract
SNRC31M/05; 31M/06; 31M/11; 31M/12; 31M/13; 31M/14; 32D/03; 32D/04; 32D/05; 32D/06; 32D/11; 32D/12
Lat/Long OENS -80.0000 -79.3333 48.5833 47.3333
Sujetskimberlites; diamant; prospection minière; datation au uranium-plomb; magnesium; ilménite; pérowskite; grenat; chromite; grenat; pyroxene monoclinique; olivine; eskers; éléments d'indice; traînées de blocs glaciaires; exploitation minière; sedimentation; assemblages de minéraux; associations de minéraux; distribution minérale; dépôts glaciaires; dépôts fluvioglaciaires; géologie économique; minéralogie; sédimentologie; géologie des dépôts meubles/géomorphologie
Illustrationsgeological sketch maps; location maps; tables; element distribution diagrams; graphs; geological time charts
ProgrammeL'Entente auxiliaire Canada-Ontario de développement du nord de l'Ontario, 1991-1995
ProgrammeL'Initiative géoscientifique ciblée (IGC-1), 2000-2003
Résumé(disponible en anglais seulement)
Sixteen kimberlite boulders were collected from three sites on the Munro and Misema River Eskers in the Kirkland Lake kimberlite field and one site on the Sharp Lake esker in the Lake Timiskaming kimberlite field. The boulders were processed for heavy-mineral concentrates from which grains of Mg-ilmenite, chromite, garnet, clinopyroxene and olivine were picked, counted and analyzed by electron microprobe. Based on relative abundances and composition of these mineral phases, the boulders could be assigned to six mineralogically different groups, five for the Kirkland Lake area and one for the Lake Timiskaming area. Their indicator mineral composition and abundances are compared to existing data for known kimberlites in both the Kirkland Lake and Lake Timiskaming areas. Six boulders from the Munro Esker form a compositionally homogeneous group (I) in which the Mg-ilmenite population is very similar to that of the A1 kimberlite, located 7-12 km N (up-ice), directly adjacent to the Munro esker in the Kirkland Lake kimberlite field. U-Pb perovskite ages of three of the group I boulders overlap with that of the A1 kimberlite. Three other boulders recovered from the same localities in the Munro Esker also show some broad similarities in Mg-ilmenite composition and age to the A1 kimberlite. However, they are sufficiently different in mineral abundances and composition from each other and from the A1 kimberlite to assign them to different groups (II-IV). Their sources could be different phases of the same kimberlite or -more likely -three different, hitherto unknown kimberlites up-ice of the sample localities along the Munro Esker in the Kirkland Lake kimberlite field. A single boulder from the Misema River esker, Kirkland Lake, has mineral compositions that do not match any of the known kimberlites from the Kirkland Lake field. This suggests another unknown kimberlite exists in the area up-ice of the Larder Lake pit along the Misema River esker. Six boulders from the Sharp Lake esker, within the Lake Timiskaming field, form a homogeneous group with distinct mineral compositions unmatched by any of the known kimberlites in the Lake Timiskaming field. U-Pb perovskite age determinations on two of these boulders support this notion. These boulders are likely derived from an unknown kimberlite source up-ice from the Seed kimberlite, 4 km NW of the Sharp Lake pit, since indicator minerals with identical compositions to those of the Sharp Lake boulders have been found in till samples collected down-ice from Seed. Based on abundance and composition of indicator minerals, most importantly Mg-ilmenite, and supported by U-Pb age dating of perovskite, we conclude that the sources of 10 of the 16 boulders must be several hitherto unknown kimberlite bodies in the Kirkland Lake and Lake Timiskaming kimberlite fields.