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Scientific article
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Geochemical, mineralogical and Re-Os isotopic constraints on the origin of Tethyan oceanic mantle and crustal rocks from the Central Pontides, northern Turkey

Publication date2017
Abstract

Chromite, ultramafic and mafic rocks from Eldivan, Yapraklı, Ayli Dağ, Küre, Elekdağ and Kızılırmak in northern Turkey have been studied to determine their min- eral and whole-rock geochemical, and Re-Os isotope geo- chemical characteristics. Most of the studied peridotites dis- play depleted but commonly V-shaped chondrite-normalized rare-earth element (REE) patterns while some peridotites as well as pyroxenites from all areas exhibit light REE depleted patterns. Olivine (forsterite 82 to 92 mol%) and spinel (chro- mium number 13 to 63) in the studied peridotites exhibit a wide range of compositions. Compositions of spinels suggest that peridotites from Eldivan, Ayli Dağ and Küre experienced relatively large degrees of partial melting (~ 15 and 19 wt%), whereas those of the Kızılırmak area most likely reflect lower melting degrees (~ 4–6 wt%). Whole-rock and mineral chemical data indicate that the ultramafic rocks are similar to abyssal and supra-subduction zone peridotites. The ultramafic rocks of the investigated areas exhibit a wide range of 187Re/188Os (0.12 to 6.6) and measured 187Os/188Os (0.122– 1.14), while the basaltic rocks from Küre, Eldivan and Kızılırmak areas have high 187Re/188Os (128–562) and mea- sured 187Os/188Os (0.724–1.943). On the other hand, chromite from Eldivan, Elekdağ and Kızılırmak show high Os contents (21.81–44.04 ppb) and low 187Re/188Os (0.015–0.818) and 187Os/188Os (0.122–0.133). Re-Os model ages (TChur) for all analyzed samples yielded scattered ages ranging from Jurassic to Proterozoic. Overall, geochemical data are interpreted to reflect different degrees of partial melting, melt – rock inter- actions and metasomatic effects that produced a heteroge- neous mantle in a supra-subduction setting.

Keywords
  • Mantle
  • Tethyan ophiolite
  • Peridotite
  • Pyroxenites
  • Re-Os isotopes
Citation (ISO format)
CELIK, Omer Faruk et al. Geochemical, mineralogical and Re-Os isotopic constraints on the origin of Tethyan oceanic mantle and crustal rocks from the Central Pontides, northern Turkey. In: Mineralogy and petrology, 2017. doi: 10.1007/s00710-017-0519-x
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ISSN of the journal0930-0708
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