MINERALOGICAL, PETROGRAPHICAL AND GEOCHEMICAL CHARACTERISTICS OF ELDIVAN OPHIOLITE (ÇANKIRI) HARZBURGITIC TECTONITES

Indexed In

Volume 143 / 2011

Authors:

Tijen ÜNER, Üner ÇAKIR

Keywords:

Eldivan Ophiolite, harzburgite, chromite, olivine, tektonite.

Abstract:

The Eldivan Ophiolite is located at the central part of the Ýzmir-Ankara-Erzincan Ophiolitic Belt and between Þabanözü, Eldivan and Korgun towns. Ophiolite consists of volcanic-sedimentary series, metamorphic series, tectonites, cumulates and sheeted dikes from bottom to top. Tectonites, which are the main subject of the study, are generally represented by harzburgites and occassionally include dunite, pyroxenolite and chromitite levels. Harzburgites display of traces of plastic deformation (foliation, lineasyon, fold) A clear orientation in minerals can be observed as a result of in the tectonic sequence and grinding mechanisms. The degree of deformation decreases upwards. Harzburgites are generally composed of olivine (60-90%) and orthopyroxene (10-35%). Clinopyroxene is rarely observed in the lower levels. A decrease in the amount of orthopyroxene and an increase in chromite ratio is observed in the upper levels. The composition of olivines is usually forsterite and orthopyroxene is enstatite. A slight decrease in Mg content noticed towards top direction. Furthermore, a decrease in chromium and an increase in aluminum content in chromites is observed towards top in the upwards direction. This situation can be explained by difference in the primary composition of the upper mantle and degree of partial melting processes.