Petrochemistry, petrology and age of the basic volcanites of the yüksekova complex around Elaziğ and Malatya

Petrography, petrochemistry, petrology, physical properties and age of the basic volcanites belonging to Yüksekova Complex cropping out around Elazığ and east-south east of Malatya were proved in this thesis study.The examined basic volcanites, as an product of imbricated prisms in the Southeast Anatolian suture zone, in places forming systematic package in the field, in places are situated on the ophiolitic and metamorphic foundation units as an tectonic or unconformity. Mesozoic and Tertiary units mostly cover as discordant the basic volcanic rocks belonging to the Yüksekova Complex. The rocks were generally cut by granitic, dacidic or doleritic dykes. The examined basic volcanites which are intercalated chert-mudstone and micritic limestone have variable thickness.The pillow lavas having purplish, burgundy, greenish colors and displaying ellipsoidal, tube-like and spherical morphologies are the most common rock types in the land. The pillows having variable dimensions show both rounding and elongation. The rates of their dimensions point out the existence of different sub-marine eruption settings.The studied basic volcanites generally contain modally plagioclase ± pyroxene ± olivine ± opaque oxides. In detail, except plagioclase, two sub-group can be distinguished as pyroxene ± olivine phyric and pyroxene + olivine phyric. The quenched textures such as variolitic and microlitic, and the doleritic textures (i.e., intergranular) are the main textures to be seen in the rocks.According to both petrographical and petrochemical classification, the rocks are basalt in composition. They are tholeiitic and tholeiitic calc-alkaline transitional in character. The spilitization common in the rocks showing alteration species such as albitization, epidotization, silisification, opacitization etc. High LOI value of the rocks is the indicator of ocean floor metamorphism/alteration. For this reason, the diagrams based on immobile element has been chosen in geochemical evaluations.Major oxide and trace element variations in the rocks show that the fractionation of plagioclase, clinopyroxene and Fe-Ti oxide played an important role in their evolution. In accordance with the petrographical and paleontological findings, incompatible element diagrams point out two different rock group compositions as transitional between IAT and N-MORB, and E-MORB. Tectonic discrimination diagrams suggest MORB-like, rift-related setting. Melting modeling based on REE shows that parental magmas of the volcanites formed by partial melting of a spinel lherzolithic mantle source. This shows also that the source deepened from intra-arc to back-arc and the melting degree decreased, with together changing of the source.Sr-Nd-Pb isotopic rates of the rocks suggest that these were derived from exhausted oceanic crust and far from interaction of continental crust. Pelagic cherts with radiolaria- primary strathigraphic related to examined basic volcanites (Yüksekova Complex) give Cenomanian-Turonian and Santonian-Campanian ages. Morphological, mineralogical-petrographical and petrochemical datas from these rocks suggest that the first group from them are Cenomanian-Turonian ages and the second group are Santonian-Campanian ages.In the closuring time of the Neotethyan Ocean, Late Cretaceous Yüksekova volcanism is represented by intra-arc volcanites developed with rifting of the intra-oceanic Yüksekova arc during Cenomanian-Turonian time, and the presence of back arc volcanism by expanding and thinning of arc crust during Santonian time.Consequently, the basic volcanic of the Yüksekova volcanism don?t consist of oceanic island arc volcanism products, at mean while, in comparison with Maden volcanism that has been previously stated to be sourced intra-continental, Yüksekova volcanism simplies to be a different age and source. Moreover, based on petrochemistry and isotope composition together with their age of the basic volcanites, Yüksekova Complex has a same source with them that were previously attributed to Kömürhan-İspendere-Guleman ophiolites.Conclusively, the basic volcanites of Yüksekova Complex do not contain only products of oceanic arc volcanism. Besides, these volcanites show dissimilarities in terms of age and source characteristics compared to Maden volcanites that were previously stated to have intra-continental source features. Moreover, the basic volcanites, which were attributed to Kömürhan-İspendere-Guleman ophiolites in previous studies, have the same source features with the basic volcanites of Yüksekova Complex.