A Study of Compaction and Cementation of Sandstones in the Athabasca Basin, Northern Saskatchewan, Canada, and Implications for Uniformity-related Uranium Mineralization

The Athabasca Basin hosts numerous high-grade unconformity-related uranium (URU) deposits, which typically occur near the unconformity between the metamorphosed basement and the quartzose sedimentary rocks. Previous studies have generally agreed upon a diagenetic-hydrothermal model in which the URU mineralization occurred at elevated temperature (>200℃) and deep-burial (5-7 km) conditions under normal geothermal conditions. However, a recent study invoked that the URU mineralization may have occurred at a relatively shallow burial depth (<3 km) and alternatively interpreted elevated temperatures (>200℃) throughout the basin as the result of higher-than-normal thermal gradient, which may be associated with deep-seated geodynamic processes. In consideration of this debate, this study investigated the compaction and cementation characteristics of the sandstones from four drill cores (Rumpel Lake, WC79-01, BL-08-01, DV10-001) located in the central part of the basin. Samples were collected from different stratigraphic levels, including the Read, Manitou Falls, Lazenby Lake, Wolverine Point, and Locker Lake formations. Three petrographic parameters, including contact index (CI), tight packing index (TPI) and intergranular volume (IGV), were used as indicators of the degree of compaction. Only moderately well- to well-sorted and matrix-poor quartz arenite samples were selected for point ii counting. It was found that below the mud-rich Wolverine Point Formation, the degree of compaction increases downward sharply from the Lazenby Lake Formation to the Read Formation, whereas the degree of quartz cementation decreases downward. However, high-degree compaction was also observed in the Locker Lake Formation above the Wolverine Point Formation. The dominance of point contacts and high abundance of quartz cement (up to 23%) in the Lazenby Lake Formation indicate a shallow burial condition at the time of quartz cementation. Reactive mass transport modeling results by using the TOUGHREACT program suggest that the petrographically discerned compaction and cementation pattern was controlled by fluid convection within sandstone successions that were confined by low-permeability aquitards. Combined with previous fluid inclusions studies indicating that the diagenetic fluid is relatively high-temperature (generally>120℃), high-salinity brine with high uranium concentration, this study further provides petrographic evidence supporting the notion that the shallow (<3 km) burial model of URU mineralization may be reasonable and large-scale fluid convection may have occurred at a time when the sedimentary rocks were not subjected to significant compaction.

Name thesis:degree_name

Master of Science (MSc)

Level thesis:degree_level

Master's

Discipline thesis:degree_discipline

Geology

Grantor dc:publisher

Faculty of Graduate Studies and Research, University of Regina

Year dc:date.issued

2020

Author dc:creator

• Wang, Yumerng

Advisor dc:contributor.advisor

• Chi, Guoxiang

Committee member dc:contributor.committeemember

• Salad Hersi, Osman

Language dc:language.iso

en

DOI

https://doi.org/10.82465/4109

OAI identifier oai:identifier

oai:uregina.scholaris.ca:10294/9272