Dale A. Leckie Geological Survey of Canada, Calgary, 3303-33st NW, Calgary, Alberta Canada, T2L 2A7

In central Saskatchewan, Canada, kimberlites were emplaced into Cretaceous marine and nonmarine clastic sediments of the Mannville and Colorado Group. One core through a kimberlite has been studied by the integration of sedimentology, volcanology, mineralogy, geochemistry, palynology, micropaleontology, organic petrology and radiometric dating. Only crater facies are observed with no hypabyssal dykes found yet. At least two episodes of kimberlite volcanism occurred in the Middle and Late Albian (between 98± 0.5 to 112 ± 1.0 Ma). Four varieties of kimberlite occur, all originating from subaerial eruptions: 1) fluvial-reworked kimberlite (point bars) within the Cantuar Formation; 2) kimberlite airfall, lapilli-tuff dominated deposits; 3) kimberlite airfall, olivine crystal-tuff dominated deposits; and 4) marine wave-reworked kimberlite (beaches and transgressive lags). The bulk of the volcanism formed conformable airfall deposits on terrestrial sediments of the Cantuar Formation and below marine shale of the Westgate Formation. Within the kimberlite airfall deposits, their were multiple primary, eruptive phases, with the volcanic style changing from passive strombolian with abundant fire-fountaining to much more explosive volcanism. The volcanism was subaerial with positive-relief tuff cones built on the Cantuar sediment paleosurface. Marine transgression associated with the Westgate Formation partially beveled the top of the kimberlite cone. The kimberlites are diamondiferous containing microdiamonds 5 to 25 µm diameter. Tmax and vitrinite reflectance values indicate that the kimberlite deposits, although derived from elevated magmatic temperatures, did not affect the temperature of country rock during deposition.