ORCID Profile
0000-0001-8209-6373
Current Organisation
University of Melbourne
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Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 12-2022
Publisher: Wiley
Date: 14-05-2020
DOI: 10.1111/SED.12729
Publisher: Elsevier BV
Date: 08-2022
Publisher: Geological Society of America
Date: 03-2021
DOI: 10.1130/B35927.1
Abstract: This study evaluates ex les of hydrothermal dolomitization in the Middle Cambrian Cathedral Formation of the Western Canadian Sedimentary Basin. Kilometer-scale dolomite bodies within the Cathedral Formation carbonate platform are composed of replacement dolomite (RD), with saddle dolomite-cemented (SDC) breccias occurring along faults. These are overlain by the Stephen Formation (Burgess Shale equivalent) shale. RD is crosscut by low- litude stylolites cemented by SDC, indicating that dolomitization occurred at very shallow depths (& km) during the Middle Cambrian. Clumped isotope data from RD and SDC indicate that dolomitizing fluid temperatures were & °C, which demonstrates that dolomitization occurred from hydrothermal fluids. Assuming a geothermal gradient of 40 °C/km, due to rift-related basin extension, fluids likely convected along faults that extended to ∼6 km depth. The negative cerium anomalies of RD indicate that seawater was involved in the earliest phases of replacement dolomitization. 84Kr/36Ar and 132Xe/36Ar data are consistent with serpentinite-derived fluids, which became more dominant during later phases of replacement dolomitization/SDC precipitation. The elevated 87Sr/86Sr of dolomite phases, and its co-occurrence with authigenic quartz and albite, likely reflects fluid interaction with K-feldspar in the underlying Gog Group before ascending faults to regionally dolomitize the Cathedral Formation. In summary, these results demonstrate the important role of a basal clastic aquifer in regional-scale fluid circulation during hydrothermal dolomitization. Furthermore, the presence of the Stephen Formation shale above the platform facilitated the build-up of fluid pressure during the final phase of dolomitization, leading to the formation of saddle dolomite-cemented breccias at much shallower depths than previously realized.
Publisher: Wiley
Date: 22-07-2020
DOI: 10.1111/BRE.12489
Abstract: Dolomitization in the Western Canadian Sedimentary Basin has been extensively researched, producing vast geochemical datasets. This provides a unique opportunity to assess the regional sources and flux of dolomitizing fluids on a larger scale than previous studies. A meta‐analysis was conducted on stable isotope, strontium isotope ( 87 Sr/ 86 Sr), fluid inclusion and lithium‐rich formation water data published over 30 years, with new petrographic, X‐ray diffraction, stable isotope and rare‐earth element (REE+Y) data. The Middle to Upper Devonian Swan Hills Formation, Leduc Formation and Wabamun Group contain replacement dolomite (RD) cross‐cut by stylolites, suggesting replacement dolomitization occurred during shallow burial. Stable isotope, REE+Y and 87 Sr/ 86 Sr data indicate RD formed from Devonian seawater, then recrystallized during burial. Apart from the Wabamun Group of the Peace River Arch (PRA), saddle dolomite cement (SDC) is more δ 18 O (PDB) depleted than RD, and cross‐cuts stylolites, suggesting precipitation during deep burial. SDC 87 Sr/ 86 Sr data indicate contributions from 87 Sr‐rich basinal brines in the West Shale Basin (WSB) and PRA, and authigenic quartz/albite suggests basinal brines interacted with underlying clastic aquifers before ascending faults into carbonate strata. The absence of quartz/albite within dolomites of the East Shale Basin (ESB) suggests dolomitizing fluids only interacted with carbonate strata. We conclude that replacement dolomitization resulted from connate Devonian seawater circulating through aquifers and faults during shallow burial. SDC precipitated during deep burial from basinal brines sourced from basal carbonates (ESB) and clastic aquifers (WSB, PRA). Lithium‐rich formation waters suggest basinal brines originated as residual evapo‐concentrated Middle Devonian seawater that interacted with basal aquifers and ascended faults during the Antler and Laramide Orogenies. These results corroborate those of previous studies but are verified by new integrated analysis of multiple datasets. New insights emphasize the importance of basal aquifers and residual evapo‐concentrated seawater in dolomitization, which is potentially applicable to other regionally dolomitized basins.
Publisher: Springer Science and Business Media LLC
Date: 05-11-2021
DOI: 10.1038/S41598-021-01118-4
Abstract: Carbonate rocks undergo low-temperature, post-depositional changes, including mineral precipitation, dissolution, or recrystallisation (diagenesis). Unravelling the sequence of these events is time-consuming, expensive, and relies on destructive analytical techniques, yet such characterization is essential to understand their post-depositional history for mineral and energy exploitation and carbon storage. Conversely, hyperspectral imaging offers a rapid, non-destructive method to determine mineralogy, while also providing compositional and textural information. It is commonly employed to differentiate lithology, but it has never been used to discern complex diagenetic phases in a largely monomineralic succession. Using spatial-spectral endmember extraction, we explore the efficacy and limitations of hyperspectral imaging to elucidate multi-phase dolomitization and cementation in the Cathedral Formation (Western Canadian Sedimentary Basin). Spectral endmembers include limestone, two replacement dolomite phases, and three saddle dolomite phases. Endmember distributions were mapped using Spectral Angle Mapper, then s led and analyzed to investigate the controls on their spectral signatures. The absorption-band position of each phase reveals changes in %Ca (molar Ca/(Ca + Mg)) and trace element substitution, whereas the spectral contrast correlates with texture. The ensuing mineral distribution maps provide meter-scale spatial information on the diagenetic history of the succession that can be used independently and to design a rigorous s ling protocol.
Publisher: Elsevier BV
Date: 10-2023
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jack Stacey.