Diagenesis of an upper Devonian carbonate-evaporite sequence: Birdbear Formation, southern interior plains, Canada
Journal Article
·
· Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes
OSTI ID:445631
- McGill Univ., Montreal, Quebec (Canada). Dept. of Earth and Planetary Sciences
The Frasnian Birdbear (Nisku) Formation is a carbonate-evaporite succession formed on a shallow restricted shelf along the eastern side of the Western Canada Sedimentary Basin. Low {delta}{sup 13}C values of the shelf limestones and dolostones (1%--5%) relative to coeval open marine settings reflect the restricted paleoenvironment of the shelf. Limestones are present only in the eastern part of the study area, and were altered by meteoric and burial diagenesis and do not retain marine {delta}{sup 18}O values. {delta}{sup 18}O values of replacement dolomites have limited range ({minus}3%--5%) and may indicate dolomitization by hypersaline marine waters having low {delta}{sup 18}O values. {sup 87}Sr/{sup 86}Sr ratios of the replacement dolomites are variable (0.7082--0.7085), but also suggest that reflux of Late Devonian seawater, possibly Famennian, was the principal dolomitizing mechanism in the Birdbear shelf. Most bedded anhydrites have {delta}{sup 34}S values (22% to 24% CDT) and {sup 87}Sr/{sup 86}Sr ratios (ca. 0.7081) that record Frasnian seawater. Dissolution and reprecipitation of sedimentary sulfates resulted in sulfate cements having up to 2% higher {delta}{sup 34}S values and slightly higher {sup 87}Sr/{sup 86}Sr ratios (ca. 0.7083). Fluids associated with anhydrite dissolution may have been derived from the overlying Famennian shelf. Late diagenetic cements in the Birdbear Shelf precipitated during the Late Cretaceous and early Tertiary during maximum burial from hot, evolved residual evaporitic brines. Residual evaporitic brines that originated on the shallow eastern Upper Devonian shelves were likely important agents of diagenesis throughout the basin.
- OSTI ID:
- 445631
- Journal Information:
- Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes, Journal Name: Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes Journal Issue: 5 Vol. 66; ISSN JSRAEA; ISSN 1073-130X
- Country of Publication:
- United States
- Language:
- English
Similar Records
delta. sup 18 O values, sup 87 Sr/ sup 86 Sr and Sr/Mg ratios of Late Devonian abiotic marine calcite: Implications for the composition of ancient seawater
Chemistry of fluid inclusions in halite from the Salina group of the Michigan basin: Implications for Late Silurian seawater and the origin of sedimentary brines
Diagenesis of early Permian evaporites and carbonates, Palo Duro Basin, Texas
Journal Article
·
Mon Jul 01 00:00:00 EDT 1991
· Geochimica et Cosmochimica Acta; (United States)
·
OSTI ID:5750889
Chemistry of fluid inclusions in halite from the Salina group of the Michigan basin: Implications for Late Silurian seawater and the origin of sedimentary brines
Journal Article
·
Wed Jan 31 23:00:00 EST 1990
· Geochimica et Cosmochimica Acta; (USA)
·
OSTI ID:6991233
Diagenesis of early Permian evaporites and carbonates, Palo Duro Basin, Texas
Conference
·
Mon Dec 31 23:00:00 EST 1984
· Geol. Soc. Am., Abstr. Programs; (United States)
·
OSTI ID:6460809