Volcanostratigraphic Controls on the Occurrence of Massive Sulfide Deposits in the Semail Ophiolite, Oman

Abstract

Research Article| September 01, 2014 Volcanostratigraphic Controls on the Occurrence of Massive Sulfide Deposits in the Semail Ophiolite, Oman Samuel A. Gilgen; Samuel A. Gilgen † 1Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland †Corresponding author: e-mail, samuel.gilgen@geo.unibe.ch Search for other works by this author on: GSW Google Scholar Larryn W. Diamond; Larryn W. Diamond 1Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland Search for other works by this author on: GSW Google Scholar Ivan Mercolli; Ivan Mercolli 1Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland Search for other works by this author on: GSW Google Scholar Khalid Al-Tobi; Khalid Al-Tobi 2Earth Secrets, P.O. Box 1242, PC 130 Athaibah, Muscat, Sultanate of Oman Search for other works by this author on: GSW Google Scholar David W. Maidment; David W. Maidment 3Mawarid Mining, P.O. Box 476, PC 321 Sohar, Sultanate of Oman Search for other works by this author on: GSW Google Scholar Robert Close; Robert Close 4Gentor Resources, P.O. Box 1053, PC 130 Athaibah, Sultanate of Oman Search for other works by this author on: GSW Google Scholar Ahmed Al-Towaya Ahmed Al-Towaya 5Directorate General of Minerals, Muscat, Sultanate of Oman Search for other works by this author on: GSW Google Scholar Economic Geology (2014) 109 (6): 1585–1610. https://doi.org/10.2113/econgeo.109.6.1585 Article history received: 23 Apr 2013 accepted: 11 Nov 2013 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Samuel A. Gilgen, Larryn W. Diamond, Ivan Mercolli, Khalid Al-Tobi, David W. Maidment, Robert Close, Ahmed Al-Towaya; Volcanostratigraphic Controls on the Occurrence of Massive Sulfide Deposits in the Semail Ophiolite, Oman. Economic Geology 2014;; 109 (6): 1585–1610. doi: https://doi.org/10.2113/econgeo.109.6.1585 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 SocietyEconomic Geology Search Advanced Search Abstract The Semail ophiolite in Oman is capped by up to 2 km of basaltic-andesitic lavas that host copper-dominant, Cyprus-type, volcanogenic massive sulfide (VMS) deposits. This study identifies multiple volcanostratigraphic horizons on which the deposits are situated, based on characterization of footwall and hanging-wall lavas from 16 deposits or deposit clusters. Comparison of field and petrographic features, compositions of igneous clinopyroxenes, and whole-rock geochemical signatures permits classification of the lavas within a modified version of the established regional volcanostratigraphy. Four extrusive units host deposits: Geotimes (earliest), Lasail, Alley, and Boninitic Alley (latest). The latter was previously known only at few localities, but this study reveals its regional extent and significance as a host for VMS deposits. The Geotimes and Lasail units represent Late Cretaceous, ocean spreading ridge and related off-axis volcanic environments, respectively. The Alley and Boninitic Alley units represent younger, subduction-related volcanism prior to Coniacian-Santonian obduction of the ophiolite. Our results show that VMS deposits occur on or near the Geotimes/Lasail and Geotimes/Alley contacts as well as entirely within the Geotimes, Lasail, Alley, and Boninitic Alley units. Highest Cu grades tend to occur in deposits lying on or within the Geotimes, whereas highest Au grades occur in deposits within the Boninitic Alley. In contrast to earlier studies, we conclude that essentially every horizon marking a hiatus in lava deposition in the Semail ophiolite, i.e., contacts between the four major eruptive units, and umbers and sedimentary chert layers within the units, has exploration potential for Cu-Au VMS deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.