C/S method for distinguishing freshwater from marine sedimentary rocks

Abstract

Research Article| June 01, 1984 C/S method for distinguishing freshwater from marine sedimentary rocks Robert A. Berner; Robert A. Berner 1Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511 Search for other works by this author on: GSW Google Scholar Robert Raiswell Robert Raiswell 1Department of Geology and Geophysics, Yale University, New Haven, Connecticut 065112Present address: Department of Earth Sciences, University of Leeds, Leeds LS2 9JT, England Search for other works by this author on: GSW Google Scholar Geology (1984) 12 (6): 365–368. https://doi.org/10.1130/0091-7613(1984)12<365:CMFDFF>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Robert A. Berner, Robert Raiswell; C/S method for distinguishing freshwater from marine sedimentary rocks. Geology 1984;; 12 (6): 365–368. doi: https://doi.org/10.1130/0091-7613(1984)12<365:CMFDFF>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract 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. On this basis, C/S ratios can be used to distinguish ancient marine from freshwater (or slightly brackish) sedimentary rocks. This is demonstrated here 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. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.