Mechanics and kinetics of incongruent feldspar dissolution

Research Article| July 01, 1983 Mechanics and kinetics of incongruent feldspar dissolution Leonard Robert Gardner Leonard Robert Gardner 1Department of Geology, University of South Carolina, Columbia, South Carolina 29208 Search for other works by this author on: GSW Google Scholar Author and Article Information Leonard Robert Gardner 1Department of Geology, University of South Carolina, Columbia, South Carolina 29208 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1983) 11 (7): 418–421. https://doi.org/10.1130/0091-7613(1983)11<418:MAKOIF>2.0.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 Leonard Robert Gardner; Mechanics and kinetics of incongruent feldspar dissolution. Geology 1983;; 11 (7): 418–421. doi: https://doi.org/10.1130/0091-7613(1983)11<418:MAKOIF>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 Examination of published feldspar dissolution data indicates that the relative rates of release of Na, K, Ca, and Si do not conform to the bulk stoichiometry of the parent feldspar. This lack of conformity is of two types: (1) nonstoichiometric release of Na, K, and Ca relative to each other and (2) nonstoichiometric release of Na, K, and Ca relative to Si. The former is attributed to inhomogeneity of the feldspar due to exsolution intergrowths and chemical zonation in crystals. The latter, which persists after accounting for secondary mineral precipitation, is due to the two-step reaction mechanism that results in the release of Si. This involves the exchange of H+ for Na+, K+, and Ca++ on the surface of the feldspar, followed by release of Al and Si to solution. Mass-balance calculations indicate that the first step accounts for a substantial proportion of the overall reaction progress and that a steady-state quantity of the H-feldspar complex is not produced. Thus, the general rate law of Aagaard and Helgeson cannot be applied to the early stages of dissolution. However, if each step is considered elementary and substrate limited, rate laws can be written for each that simulate the delayed release of Si relative to Na, K, and Ca. These rate laws can also be shown to result in linear kinetics under certain conditions (e.g., substrate saturation and steady-state H-feldspar). 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.