Evaluation of the potential for dissolved oxygen ingress into deep sedimentary basins during a glaciation event

• Autores: Bea, Sergio Andrés; Su, Danyang; Mayer, Klaus Ulrich; MacQuarrie, T. B.
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Reactive transport modeling; Thermal-Hydro-Chemical and Mechanical coupling; Sedimentary basins; Glaciation-deglaciation cycle; Oxygen ingress; Redox-buffering minerals; Solid organic matter
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Geochemical conditions in intracratonic sedimentary basins are currently reducing, even at relatively shallow depths. However, during glaciation-deglaciation events, glacial meltwater production may result in enhanced recharge (Bea et al., 2011; and Bea et al., 2016) potentially having high concentrations of dissolved oxygen (O2). In this study, the reactive transport code Par-MIN3PTHCm was used to perform an informed, illustrative set of simulations assessing the depth of penetration of low salinity, O2-rich, subglacial recharge. Simulation results indicate that the large-scale basin hydrostratigraphy, in combination with the presence of dense brines at depth, results in low groundwater velocities during glacial meltwater infiltration, restricting the vertical ingress of dilute recharge waters. Furthermore, several geochemical attenuation mechanisms exist for O2, which is consumed by reactions with reduced mineral phases and solid organic matter (SOM). The modeling showed that effective oxidative mineral dissolution rates and SOMoxidation rates between 5 × 10-15 and 6 × 10-13 mol dm-3 bulk s-1 were sufficient to restrict the depth of O2 ingress to less than 200m.These effective rates are low and thus conservative, in comparison to rates reported in the literature. Additional simulations with more realistic, yet still conservative, parameters reaffirm the limited ability for O2 to penetrate into sedimentary basin rocks during a glaciation-deglaciation event.
Fil: Bea, Sergio Andrés. Universidad Nacional del Centro de la Provincia de Buenos Aires. Rectorado. Instituto de Hidrología de Llanuras - Sede Tandil. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Hidrología de Llanuras - Sede Tandil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Su, Danyang. University of British Columbia; Canadá
Fil: Mayer, Klaus Ulrich. University of British Columbia; Canadá
Fil: MacQuarrie, T. B.. University of New Brunswick; Canadá