Sedimentation and early sulfide diagenesis of Harmon Member
Pyrite is ubiquitous in the Albian Harmon Member (Peace River Formation) in concentrations from less than 0.2 to 8.5 wt. %. Petrographic observations show two distinct modes of occurrence that are stratigraphically controlled. In neritic laminated mudstone, pyrite occurs dominantly as very fine-grained (< 20 ..mu..m), disseminated framboids. In moderately bioturbated pro-delta (transition zone) mudstone and siltstone, pyrite occurs as framboidal aggregates, burrow-filling cement, and rarely as a cement in peloidal muds. The preservation of primary sedimentary structures and the absence of bioturbation in neritic mudstones indicate deposition beneath anoxic to euxinic bottom waters. Elevated C/S values may further indicate a euxinic depositional environment. Consistently low /sup 34/S//sup 32/S values indicate unrestricted availability of sulfate for bacterially mediated reduction. Excess iron (relative to stoichiometric pyrite), a lack of C/S correlation, and elevated /sup 34/S//sup 32/S values show that sulfate availability was the limiting factor in transition zone sediments. Sulfate availability was probably controlled by episodic sedimentation and bioturbation.
- Research Organization:
- Univ. of Calgary, Alberta (Canada)
- OSTI ID:
- 6376555
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 73:3; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Sulfur isotope variability in biogenic pyrite: Reflections of heterogeneous bacterial colonization?
Sulfur isotopic analyses of disseminated pyrite in cretaceous black and green mudstones
Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALBERTA
ALLUVIAL DEPOSITS
CANADA
CHALCOGENIDES
DIAGENESIS
EVEN-EVEN NUCLEI
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
IRON COMPOUNDS
IRON SULFIDES
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MINERALS
NORTH AMERICA
NUCLEI
PYRITE
ROCKS
SEDIMENTARY ROCKS
SEDIMENTATION
SILTSTONES
STABLE ISOTOPES
SULFIDE MINERALS
SULFIDES
SULFUR 32
SULFUR 34
SULFUR COMPOUNDS
SULFUR ISOTOPES
TRANSITION ELEMENT COMPOUNDS