Aragonite-to-calcite transformation during fresh-water diagenesis of carbonates: Insights from pore-water chemistry

Research Article| August 01, 1988 Aragonite-to-calcite transformation during fresh-water diagenesis of carbonates: Insights from pore-water chemistry DAVID A. BUDD DAVID A. BUDD 1Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1988) 100 (8): 1260–1270. https://doi.org/10.1130/0016-7606(1988)1002.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DAVID A. BUDD; Aragonite-to-calcite transformation during fresh-water diagenesis of carbonates: Insights from pore-water chemistry. GSA Bulletin 1988;; 100 (8): 1260–1270. doi: https://doi.org/10.1130/0016-7606(1988)1002.3.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 SocietyGSA Bulletin Search Advanced Search Abstract Dissolved strontium and calcium concentrations in fresh-water lenses (FWL) and associated mixing zones (MZ) on two small, Holocene ooid-sand islands in the Schooner Cays, Bahamas, were monitored during a 1-yr period to quantitatively analyze the transformation of aragonite to calcite. The observed characteristics of this mass transfer are functions of climate and hydrology.Aragonite-to-calcite transformation in all hydrologic zones is primarily associated with meteoric recharge. The transformation occurs throughout the FWL and in the MZ to relative salinities of 19% and 36% sea water on the two islands. Rates of transformation are rapid in all zones and are greatest in the FWL. A limestone composed of 100% calcite should form from an aragonite precursor within 4,700 to 15,600 yr in the FWL, and within 8,700 to 60,000 yr in the upper MZ.Efficiencies of transformation can vary between hydrologic zones due to PCO2 effects; yet, the efficiency of the entire system (FWL + MZ) is high (87%). This indicates that most CaCO3 derived from aragonite dissolution is reprecipitated as calcite somewhere in the fresh-water system or upper mixing zone.CO2 effects, fresh-water-sea-water mixing, and the differing solubilities between aragonite and calcite all drive the mass transfer. The latter is the most significant, accounting for up to nine times more mass transfer than CO2 effects and at least ten times more mass transfer than fresh-water-sea-water mixing. Differing solubilities should also cause mass transfer to occur throughout the hydrologic cycle, but it apparently becomes ineffective after the rainy season, possibly due to the inhibition of calcite precipitation. 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.