Mineral chemistry of ultramafic and mafic cumulates an indicator of the arc-related origin of Mersin ophiolite (southern Turkey)


Parlak O., Delaloye M., Bingol E.

GEOLOGISCHE RUNDSCHAU, vol.85, no.4, pp.647-661, 1996 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 85 Issue: 4
  • Publication Date: 1996
  • Doi Number: 10.1007/bf02440102
  • Title of Journal : GEOLOGISCHE RUNDSCHAU
  • Page Numbers: pp.647-661

Abstract

The Mersin ophiolite, represented by approximately 6-km-thick oceanic lithospheric section on the southern flank of the Taurus calcareous axis, formed in the Mesozoic Neo-Tethyan ocean some time during Late Cretaceous in southern Turkey. The ultramafic and mafic cumulates having over 3 km thickness consist of dunite+/-chromite, wehrlite, clinopyroxenite at the bottom and pass into gabbroic cumulates in which leucogabbro, olivine-gabbro and anorthosite are seen. Crystallization order is olivine (Fo(91-80)) +/-chromian spinel (Cr# 60-80), clinopyroxene (Mg# (95-77)), plagioclase (An(95.6-91.6)) and orthopyroxene (Mg# (68-77)) Mineral chemistry of ultramafic and mafic cumulates suggest that highly magnesian olivines, clinopyroxenes and absence of plagioclase in the basal ultramafic cumulates are in good agreement with products of high-pressure crystal fractionation of primary basaltic melts beneath an island-are environment. Major, trace element geochemistry of the cumulative rocks also indicate that Mersin ophiolite was formed in an are environment. Coexisting Ca-rich plagioclase and Fo-rich olivine in the gabbroic cumulates show are cumulate gabbro characteristics. Field relations as well as the geochemical data support that Mersin ophiolite formed in a supra-subduction zone tectonic setting in the southern branch of the Neo-Tethys in southern Turkey.