Glassy Abyssal Basalts, Atlantic Sea Floor near St. Paul's Rocks: Petrography and Composition of Secondary Clay Minerals

Abstract

Research Article| February 01, 1973 Glassy Abyssal Basalts, Atlantic Sea Floor near St. Paul's Rocks: Petrography and Composition of Secondary Clay Minerals WILLIAM G. MELSON; WILLIAM G. MELSON 1Department of Mineral Sciences, Smithsonian Institution, Washington, D.C. 20560 Search for other works by this author on: GSW Google Scholar GEOFFREY THOMPSON GEOFFREY THOMPSON 2Woods Hole Oceanographic Institute, Woods Hole, Massachusetts 02543 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM G. MELSON 1Department of Mineral Sciences, Smithsonian Institution, Washington, D.C. 20560 GEOFFREY THOMPSON 2Woods Hole Oceanographic Institute, Woods Hole, Massachusetts 02543 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1973) 84 (2): 703–716. https://doi.org/10.1130/0016-7606(1973)84<703:GABASF>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 Email Permissions Search Site Citation WILLIAM G. MELSON, GEOFFREY THOMPSON; Glassy Abyssal Basalts, Atlantic Sea Floor near St. Paul's Rocks: Petrography and Composition of Secondary Clay Minerals. GSA Bulletin 1973;; 84 (2): 703–716. doi: https://doi.org/10.1130/0016-7606(1973)84<703:GABASF>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 SocietyGSA Bulletin Search Advanced Search Abstract Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement.Hyaloclastite and pillow lavas were dredged a short distance northwest of St. Paul's Rocks. These rocks are more alkaline than the basalts erupted from spreading ridges. In addition to olivine and plagioclase phenocrysts, the rocks contain complex sector-zoned pyroxene phenocrysts. Fe2O3/FeO of about 0.20 was calculated for the glass from FeO-MgO partitioning between olivine and liquid.Clay minerals, mainly potassian smectite, are abundant in both rock types. These are divided into three groups on the basis of their composition, optical properties, and mode of occurrence. All these groups have structural formulas that are intermediate between dioctahedral and trioctahedral smectite. Potassium, sodium, and calcium, in order of abundance, are the dominant interlayer cations. These smectites occur with small amounts of analcite and even less abundant phillipsite. The abundance and composition of these clays suggest that they are important traps for potassium and magnesium from sea water. 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.