The dunitic mantle-crust transition zone in the Oman ophiolite: Residue of melt-rock interaction, cumulates from high-MgO melts, or both?

Abstract

Research Article| January 01, 2013 The dunitic mantle-crust transition zone in the Oman ophiolite: Residue of melt-rock interaction, cumulates from high-MgO melts, or both? Bénédicte Abily; Bénédicte Abily Toulouse University, CNRS–UMR 5563, GET, OMP, 31400 Toulouse, France Search for other works by this author on: GSW Google Scholar Georges Ceuleneer Georges Ceuleneer Toulouse University, CNRS–UMR 5563, GET, OMP, 31400 Toulouse, France Search for other works by this author on: GSW Google Scholar Author and Article Information Bénédicte Abily Toulouse University, CNRS–UMR 5563, GET, OMP, 31400 Toulouse, France Georges Ceuleneer Toulouse University, CNRS–UMR 5563, GET, OMP, 31400 Toulouse, France Publisher: Geological Society of America Received: 27 Feb 2012 Revision Received: 30 Jun 2012 Accepted: 16 Jul 2012 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2012 Geological Society of America Geology (2013) 41 (1): 67–70. https://doi.org/10.1130/G33351.1 Article history Received: 27 Feb 2012 Revision Received: 30 Jun 2012 Accepted: 16 Jul 2012 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 Bénédicte Abily, Georges Ceuleneer; The dunitic mantle-crust transition zone in the Oman ophiolite: Residue of melt-rock interaction, cumulates from high-MgO melts, or both?. Geology 2013;; 41 (1): 67–70. doi: https://doi.org/10.1130/G33351.1 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 The contact between mantle peridotite and gabbro from the lower oceanic crust is usually underlined by a horizon of dunite. The origin of this dunitic transition zone (DTZ) is still debated. It is viewed either as a pile of cumulus olivine from high-MgO melts, or as former mantle peridotite pervasively percolated by melts undersaturated with pyroxene (e.g., as mid-oceanic ridge basalts [MORBs] at low pressure), and transformed into dunite. We show that the two hypotheses are not mutually exclusive, although they do not account for the same parts of the DTZ. We determined a petrological profile through a 330-m-thick DTZ that developed at the top of a mantle diapir in the Oman ophiolite. The lowermost 280 m have a reactional origin: olivine and Cr-spinel record the complex percolation and interaction history between mantle peridotite and MORB. In the uppermost 50 m, chemical trends become consistent with a cumulus origin of the dunite, olivine crystallization being a prelude to the crystallization of the overlying gabbros. The DTZ develops largely in response to melt-rock reaction, consistent with the “reactive filter” hypothesis, but the proportion of cumulate dunite is high enough to require parent melts with a significantly higher Mg content than the most primitive MORB erupted on the seafloor. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.