Importance of iron-rich tholeiitic magmas at divergent plate margins: A reappraisal

Abstract

Research Article| March 01, 1991 Importance of iron-rich tholeiitic magmas at divergent plate margins: A reappraisal C. Kent Brooks; C. Kent Brooks 1Institut of Petrology, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Search for other works by this author on: GSW Google Scholar Lotte Melchior Larsen; Lotte Melchior Larsen 2Geological Survey of Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Search for other works by this author on: GSW Google Scholar Troels F.D. Nielsen Troels F.D. Nielsen 2Geological Survey of Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Search for other works by this author on: GSW Google Scholar Author and Article Information C. Kent Brooks 1Institut of Petrology, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Lotte Melchior Larsen 2Geological Survey of Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Troels F.D. Nielsen 2Geological Survey of Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1991) 19 (3): 269–272. https://doi.org/10.1130/0091-7613(1991)019<0269:IOIRTM>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 MailTo Tools Icon Tools Get Permissions Search Site Citation C. Kent Brooks, Lotte Melchior Larsen, Troels F.D. Nielsen; Importance of iron-rich tholeiitic magmas at divergent plate margins: A reappraisal. Geology 1991;; 19 (3): 269–272. doi: https://doi.org/10.1130/0091-7613(1991)019<0269:IOIRTM>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 When a tholeiitic liquid differentiates, it may give rise to either iron-poor, silica-rich (rhyolitic) differentiates or to iron-rich, silica-poor differentiates, as found in the Skaergaard intrusion. Iron-rich differentiated liquids are rare among erupted rocks, but are found in small quantities from several localities at divergent plate margins. Among the Tertiary basalts and intrusions in East Greenland, normal erupted basalts may be mixtures of primitive liquid and differentiated iron-rich liquid, which exists at depth but normally does not reach the surface because of its high density. The evolved liquids of the Skaergaard intrusion were of this kind. Data from mid-oceanic ridges confirm this view. We believe that iron-rich differentiated liquids, despite their scarcity on the surface, are much more voluminous at depth, as picrites, at the other side of the density minimum attained during liquid evolution, are thought to be. The trend toward iron enrichment develops when the tholeiitic magma differentiates in a closed system at a relatively low oxidation state, whereas the trend toward silica enrichment and iron depletion occurs when the magma has interacted with the oxidized and hydrated surroundings in the crust. 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.