Geochemical modeling of diagenesis, hydrothermal alteration, and unconformity-related uranium mineralization in the Athabasca Basin, Saskatchewan, Canada
type: CreativeWork
description: Unconformity-related uranium (URU) deposits in the Athabasca Basin were interpreted to have formed through interactions between oxidizing basinal fluids and reducing basement-derived fluids or basement lithologies under diagenetic-hydrothermal conditions. However, there is controversy regarding whether U is ultimately derived from the basin or the basement, fluid flow mechanisms responsible for metal leaching and transport, and deposition mechanisms of ores. This study uses geochemical modeling to: 1) determine fluid flow patterns responsible for U leaching and transport in the Athabasca basin; 2) recognize critical factors controlling ore deposition near the unconformity intersected by basement faults; and 3) constrain metal sources, fluid migration pathways, and ore precipitation mechanisms for U and associated elements, including Ni, Co, and As, which are anomalously enriched within some URU deposits. Petrographic observation on four drill cores indicates that the top of the sandstone succession below a mud-rich aquitard is characterized by extensive quartz overgrowths, whereas the basal part contains little cement and shows extensive dissolution features. Reactive transport modeling indicates that such a quartz cementation-dissolution pattern can be produced only if the sandstones are sufficiently permeable and thick so that the Rayleigh number exceeds the critical value for thermal convection. The results indicate that thermal convection did occur in the Athabasca Basin and may have facilitated the large-scale circulation of diagenetic fluids to leach and transport U within sandstones. Reactive transport modeling further shows that significant URU mineralization occurs at a fault-unconformity intersection only if thermal convection and basin- basement fluid mixing take place concurrently. If there is no thermal convection in the basin, only sparse U mineralization occurs along the unconformity. If insufficient amount of reducing fluid is provided from the basem…
abstract: Unconformity-related uranium (URU) deposits in the Athabasca Basin were interpreted to have formed through interactions between oxidizing basinal fluids and reducing basement-derived fluids or basement lithologies under diagenetic-hydrothermal conditions. However, there is controversy regarding whether U is ultimately derived from the basin or the basement, fluid flow mechanisms responsible for metal leaching and transport, and deposition mechanisms of ores. This study uses geochemical modeling to: 1) determine fluid flow patterns responsible for U leaching and transport in the Athabasca basin; 2) recognize critical factors controlling ore deposition near the unconformity intersected by basement faults; and 3) constrain metal sources, fluid migration pathways, and ore precipitation mechanisms for U and associated elements, including Ni, Co, and As, which are anomalously enriched within some URU deposits. Petrographic observation on four drill cores indicates that the top of the sandstone succession below a mud-rich aquitard is characterized by extensive quartz overgrowths, whereas the basal part contains little cement and shows extensive dissolution features. Reactive transport modeling indicates that such a quartz cementation-dissolution pattern can be produced only if the sandstones are sufficiently permeable and thick so that the Rayleigh number exceeds the critical value for thermal convection. The results indicate that thermal convection did occur in the Athabasca Basin and may have facilitated the large-scale circulation of diagenetic fluids to leach and transport U within sandstones. Reactive transport modeling further shows that significant URU mineralization occurs at a fault-unconformity intersection only if thermal convection and basin- basement fluid mixing take place concurrently. If there is no thermal convection in the basin, only sparse U mineralization occurs along the unconformity. If insufficient amount of reducing fluid is provided from the basem…
author: Wang, Yumeng
language: en
date published: 2024-01
date modified: 2026-07-24T04:03:32Z
provider: University of Regina
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Faculty of Graduate Studies and Research, University of Regina

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10294/16417

PropertyValue
property ID: DOI
value: 10.82465/4102