Generation of alkalic basalt by crystal fractionation of tholeiitic magma

Abstract

Research Article| May 01, 1999 Generation of alkalic basalt by crystal fractionation of tholeiitic magma Terry R. Naumann; Terry R. Naumann 1Geology Department, University of Alaska, Anchorage, Alaska 99508, USA Search for other works by this author on: GSW Google Scholar Dennis J. Geist Dennis J. Geist 2Department of Geology and Geological Engineering, University of Idaho, Moscow, Idaho 83844, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Terry R. Naumann 1Geology Department, University of Alaska, Anchorage, Alaska 99508, USA Dennis J. Geist 2Department of Geology and Geological Engineering, University of Idaho, Moscow, Idaho 83844, USA Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1999) 27 (5): 423–426. https://doi.org/10.1130/0091-7613(1999)027<0423:GOABBC>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Terry R. Naumann, Dennis J. Geist; Generation of alkalic basalt by crystal fractionation of tholeiitic magma. Geology 1999;; 27 (5): 423–426. doi: https://doi.org/10.1130/0091-7613(1999)027<0423:GOABBC>2.3.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 SocietyGeology Search Advanced Search Abstract Contemporaneous alkalic and tholeiitic basalts from Cerro Azul volcano, in the Galápagos archipelago, are related by fractional crystallization in the lower crust and upper mantle. The higher pressures enhance augite crystallization, which depletes the residual liquids in silica while enriching them in K and Na, just as predicted by phase-equilibria experiments. Such occurrences have also been reported from other ocean islands. The common aspect of these alkalic suites is that they occur at volcanoes that have relatively low magma-supply rates, which leads to the development of deep magma bodies and the production of alkali-olivine basalts by fractional crystallization of a tholeiitic parent. During more robust phases of magmatism, tholeiitic magmas ascend into the upper crust and produce a low-pressure tholeiitic differentiation trend. 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.