GD Anadolu Orojenik Kuşağı ofiyolitlerinin manto peridotitleri bileşimleri ve petrolojisi: Ana element, iz element jeokimyası ve mineral kimyası

Abstract

The aim of this study is to reveal mantle processes such as tectonic environment, partial melting degree and melt-rock interactions of mantle peridotite (harzburgite and dunite) of Kızıldağ, Koçali and Guleman ophiolites outcropping in South Eeast Anatolia Ophiolite Belt. For this purpose, geochemical analyses of whole rock (main oxide, trace element, Rare Earth Element) and mineral base (mineral chemistry) in mantle peridotite samples which are generally harzburgite and dunite, show different degrees of serpentinization, were carried out in various laboratories. As a result of all of this study, the clinopyroxene minerals of harzburgite and dunite type rocks belonging to the mantle peridotites of the ophiolites are extremely depleted. So it seems that these samples have very low Al2O3 (% 0−4,93 %wt.) and CaO (%0.10−2.38 %wt.) and high MgO (39.27−49.58 %wt.) content in whole rock. In addition, the fact that these rocks have high Cr# in spinels is interpreted because the mantle peridotites contain moderate to high degrees of partial melting residues. On the other hand, enrichment of Al2O3 and CaO contents and decrease of Cr# values of spinels in proportion to increasing clinopyroxene abundances of some mantle peridotite samples result from lower degree melting residues than other samples. Enrichment of mantle peridotites, especially light REE and Large Ion Lithophile Elements (LILE), is a result of metasomatism with melts having different composition in subduction zones. As a result, especially considering the results of mineral chemistry, trace element and RRE analysis, it is thought that the mantle peridotites of the ophiolites are the residual rocks which form the subject of the project are formed in the mid-ocean ridge environment and then exposed to the second phase depletion in the subduction zone (forearc environment) and in this period, it is thought that metasomatized by slab derived melt in various composition.