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C/S method for distinguishing freshwater from marine sedimentary rocks

Robert A. Berner and Robert Raiswell
C/S method for distinguishing freshwater from marine sedimentary rocks
Geology (Boulder) (June 1984) 12 (6): 365-368


In organic-rich sediments laid down in fresh water, much less diagenetic pyrite is formed than in analogous marine sediments because of the much lower concentrations of dissolved sulfate found in most fresh waters as compared to seawater. As a result, modern organic-rich freshwater sediments exhibit a much higher organic carbon-to-pyrite sulfur ratio (C/S) than marine sediments with similar organic contents. This is demonstrated for several Carboniferous shales and siltstones. The C/S technique cannot distinguish brackish-water sediments deposited under salinities greater than half that of seawater from marine sediments, as demonstrated by analyses of modern Chesapeake Bay sediments. Also, the method is not applicable to nearly pure limestones or to rocks low in organic matter (less than about 1% organic carbon). Saline (high sulfate) phases of ancient lakes can be distinguished from nonsaline phases using the C/S method.--Modified journal abstract.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 12
Serial Issue: 6
Title: C/S method for distinguishing freshwater from marine sedimentary rocks
Affiliation: Yale Univ., Dep. Geol. and Geophys., New Haven, CT, United States
Pages: 365-368
Published: 198406
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 30
Accession Number: 1984-038819
Categories: Sedimentary petrologyGeochemistry of rocks, soils, and sediments
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N36°55'00" - N39°37'00", W76°32'60" - W75°40'00"
N50°00'00" - N59°00'00", W08°00'00" - E01°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 1984
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