Geochemical Properties And Rodingitization Of Diabese Dykes Cutting Peridotites in Yüksekova Complex (Özalp, Van-Turkey)

In this study, the geology of diabase dykes which cut peridotites of Yüksekova Complex (Özalp,Van, Turkey) and the effects of Ca metasomatism that caused the metamorphism of these peridotites were investigated. Within the light of mineralogical and petrographical studies and geochemical data; it was determined that diabase dykes that cut peridotites in Yüksekova Complex had shown rodingitization in various degrees due to Ca metasomatism. Depending on this metasomatism, Ca-Al-Mg rich silicates were formed. The mineralogy of rodingitized dykes with ophitic texture is composed of diopside, plagioclase, hydrogrossularite, chlorite, epidote and in minor amounts phlogopite, prehnite, apatite, calcite, opaque minerals. Metasomatism caused enrichment of Ca and depletion of SiO2 in whole rock major oxides of dykes in tholeiitic character. So, dykes were divided into three different subgroups. The first group is formed from high grade rodingitized diabase dykes (~38.0?42.0 wt. % in SiO2; 19.0?26.0 wt. % in CaO). The grade of rodingitization in diabase dykes forming the second group is relatively low (~42.5?43.0 wt. % in SiO2; 14.5?15.0 wt. % in CaO). However, the effect of rodingitization has not been encountered due to results of both petrographical and geochemical analyses in diabase dykes which form the third group (~47.0?50.0 wt. % in SiO2; 10.0?12.0 wt. % in CaO). It is considered that in rodingitized dykes of which are enriched by trace and REE (Rare Earth Element) contents, the fluids affecting the metasomatic source have developed as a result of interactions with other rocks which were enriched more in these elements. It is also contemplated that the local geology, tectonical structure of the environment and the heat, oxygen fugacity and chemical composition in fluids which would develop due to those factors are significant in this interaction.