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Geology Talk

Wed., Apr. 3, 2019 4:00 p.m. - Wed., Apr. 3, 2019 4:30 p.m.

Location: Classroom Building 130

Presenter: Mr. Yumeng Wang, M.Sc. Student in the Department of Geology, University of Regina

Abstract: The Proterozoic Athabasca Basin in northern Saskatchewan is a uraniferous basin associated with many world-class U deposits. It is important to know the burial and thermal conditions of the basin in order to understand the U mineralization environment. The basin stratigraphy is divided into 9 formations, from bottom to top: Fair Point, Read, Manitou Falls, Lazenby Lake, Wolverine Point, Locker Lake, Otherside, Douglas and Carswell. This study aims to examine the compaction and cementation characteristics of the sandstone in the basin through statistical petrographic work on samples from four drill cores in the central part of the basin, and to carry out numerical modeling of dissolution and precipitation of silica in order to explain the observed dissolution-cementation patterns. The results indicate that the compaction of quartz wacke tends to be related with the abundance of the matrix, whereas that of quartz arenite is intimately related to the depth as indicated by packing parameters including compaction index (CI), tight packing index (TPI) and intergranular volume (IGV), which were established with point counting data. Most of the samples studied were sandstones from the Read to Lazenby Lake formations below the mud-rich Wolverine Formation. The sandstones from the top of the Lazenby Lake Formation is characterized by high degree of quartz cementation (up to 23%), and the degree of compaction increases sharply downward to the Read Formation. Such a compaction and cementation pattern may be related to a two-stage diagenetic evolution history: 1) coupled silica dissolution (at the bottom) and cementation (at the top) related to a fluid convection system before significant compaction of the sandstones, and 2) subsequent compaction of the sandstones that had not been cemented. Numerical modeling of reactive mass transport involving only silica using TOUGHREACT yielded a silica dissolution – cementation pattern similar to petrographic observations.