Hydrothermal minerals and alteration rates at Surtsey volcano, Iceland

Abstract

Research Article| May 01, 1986 Hydrothermal minerals and alteration rates at Surtsey volcano, Iceland SVEINN P. JAKOBSSON; SVEINN P. JAKOBSSON 1Icelandic Museum of Natural History, Reykjavik, Iceland Search for other works by this author on: GSW Google Scholar JAMES G. MOORE JAMES G. MOORE 2U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information SVEINN P. JAKOBSSON 1Icelandic Museum of Natural History, Reykjavik, Iceland JAMES G. MOORE 2U.S. Geological Survey, Menlo Park, California 94025 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1986) 97 (5): 648–659. https://doi.org/10.1130/0016-7606(1986)97<648:HMAARA>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 SVEINN P. JAKOBSSON, JAMES G. MOORE; Hydrothermal minerals and alteration rates at Surtsey volcano, Iceland. GSA Bulletin 1986;; 97 (5): 648–659. doi: https://doi.org/10.1130/0016-7606(1986)97<648:HMAARA>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 The volcanic island Surtsey, off the south coast of Iceland, was created by volcanic activity in 1963–1967. Core from a 181-m-deep hole extending 123 m below sea level shows the results of 12 yr of hydrothermal alteration of basaltic tephra. The primary cause of heating of the tephra and of development of the hydrothermal system was the intrusion of dikes below sea level. At present, the hottest part of the hole, at a maximum temperature of 150 °C, is cooling at ∼0.9 °C per year. Palagonitization of sideromelane glass, a dominant constituent of the tephra, is an important alteration process that is strongly temperature dependent, the rate doubling for every 12 °C increase. At 60 °C, <40% of the glass is palagonitized, but above 100 °C, >90% is palagonitized. Above 120 °C, olivine crystals are replaced on their edges by nontronite; the thickness of clay doubles for each 8 °C increase. Ten hydrothermal minerals have crystallized in the tephra at 25 to 150 °C; the dominant species are smectite (nontronite), analcite, phillipsite, and tobermorite. The primary clay species of palagonite is probably nontronite. Other minerals are halite, opal, calcite, chabazite, xonotlite, anhydrite, and gypsum. No major differences in mineral occurrence are noted above and below sea level, but phillipsite and tobermorite tend to grow larger below sea level, even at the same temperature. Analcite appears at lower temperature (55 °C) above sea level than below sea level (75 °C). Anhydrite is most abundant deep in the hole, where inflowing, cool sea water precipitated sulfate due to reduced sulfate solubility at higher temperatures. 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.