The geochemistry of postkinematic mafic dike swarms and subophiolitic metabasites, Pozanti-Karsanti ophiolite, Turkey: Evidence for ridge subduction

Abstract

Research Article| July 01, 1995 The geochemistry of postkinematic mafic dike swarms and subophiolitic metabasites, Pozanti-Karsanti ophiolite, Turkey: Evidence for ridge subduction Jennifer N. Lytwyn; Jennifer N. Lytwyn 1Department of Geosciences, University of Houston, Houston, Texas 77204-5503 Search for other works by this author on: GSW Google Scholar John F. Casey John F. Casey 1Department of Geosciences, University of Houston, Houston, Texas 77204-5503 Search for other works by this author on: GSW Google Scholar Author and Article Information Jennifer N. Lytwyn 1Department of Geosciences, University of Houston, Houston, Texas 77204-5503 John F. Casey 1Department of Geosciences, University of Houston, Houston, Texas 77204-5503 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1995) 107 (7): 830–850. https://doi.org/10.1130/0016-7606(1995)107<0830:TGOPMD>2.3.CO;2 Article history First Online: 01 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 Jennifer N. Lytwyn, John F. Casey; The geochemistry of postkinematic mafic dike swarms and subophiolitic metabasites, Pozanti-Karsanti ophiolite, Turkey: Evidence for ridge subduction. GSA Bulletin 1995;; 107 (7): 830–850. doi: https://doi.org/10.1130/0016-7606(1995)107<0830:TGOPMD>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 SocietyGSA Bulletin Search Advanced Search Abstract Doleritic and gabbroic dike swarms cut the Pozanti-Karsanti ophiolite and basal metamorphic sole but do not extend into the underlying melange or platform carbonates. Dike emplacement therefore postdated formation of the ophiolite and metamorphic sole but predated final obduction onto the Tauride-Anatolide Platform. The dikes are compositionally similar to island-arc basalts and basaltic andesites and were affected by retrograde, static hydrothermal metamorphism over temperatures ranging from ∼900 C to below 450 C. Geochemical modeling of trace elements (including REEs) show that the dikes are possibly fractionated products of multiple, compositionally variable parental magmas. The range of parental magmas is interpreted to represent variably mixed melt increments generated through polybaric fractional or continuous melting within a column of rising mantle material. Melt increments extracted from shallower parts of the melting column at lower pressures are more refractory and apparently pooled less efficiently than melt fractions generated from deeper sources and higher pressures. Amphibolite and greenschist facies metabasalt from the subophiolitic sole represent metamorphosed alkalic basalt and MORB-like basalt, respectively. The Pozanti-Karsanti ophiolite probably constituted part of the fore-arc mantle wedge directly above an intra-oceanic subduction zone, whereas the metamorphic sole represents material progressively transferred and accreted to the base of the ophiolite from the downgoing oceanic plate during subduction. Since late-stage pre-obduction dike swarms transect the metamorphic sole, a probable subduction plane, melt generation must have occurred below the Wadati-Benioff Zone and not in the overlying mantle wedge. A probable source of parental liquids for the dikes may therefore be a subducting Neo-Tethyan spreading center. 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.