Petrography and geochemsitry of the tectonomagmatic units cropping out between Baskil and Sivrice (Elazığ)

ABSTRACTPhD THESISPETROGRAPHY AND GEOCHEMISTRY OF THETECTONOMAGMATIC UNITS CROPPING OUT BETWEENBASKİL AND SİVRİCE (ELAZIĞ)Tamer RIZAOĞLUDEPARTMENT OF GEOLOGYINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF CUKUROVASupevisor : Prof. Dr. Fikret İŞLERYear : 2006, Pages: 259Jury : Prof. Dr. Fikret İŞLERProf. Dr. Servet YAMANProf. Dr. Mesut ANILProf. Dr. Halil BAŞAssoc. Prof. Dr. Osman PARLAKThere are a number of tectono-magmatic/stratigraphic units that have intrusive and tectonic contactrelationships among each other in Baskil-Sivrice (Elazığ) area. These are namely; Malatya-Keban platform,Kömürhan ophiolite, Ensimatic island arc unit and Baskil granitoid. The Late Cretaceous Kömürhan ophiolitecrops out to the west of the Lake Hazar, and has a genetic link with the İspendere ophiolite to the west andGuleman ophiolite to the east. In the north the Kömürhan ophiolite tectonically overlain by the Malatya-Kebanplatform and in turn intruded by the Baskil granitoid whereas in the south it is thrust over the Middle-EoceneMaden Complex.The Kömürhan ophiolite presents an intact oceanic lithospheric section and comprises from bottom totop tectonites, cumulates, isotropic gabbros, sheeted dike complex and volcanics. A thin slice of metamorphicsole rocks, metamorphosed in the amphibolite facies during the intra-oceanic subduction, is observed at the baseof the tectonites. The tectonites are represented by the serpentinized harzburgite and lherzolite. The ultramaficcumulate rocks overlying the tectonites are represented by wehrlites, and in some areas they also exhibit intrusivecontact relationships with the overlying gabbroic cumulate rocks. The mafic cumulates are characterized byolivine gabbro, gabbro, gabbro-norite and amphibole gabbro and pass upward into the isotropic gabbroic rocks.The sheeted dike complex is represented by diabase, microdiorite and quartz-microdiorite dikes exhibitingvariable thicknesses ranging from 15-20 cm to 75-100 cm without pronounced chilled margins. The volcanicrocks are wide-spread in the region and have tectonic contact relationship with the rock units of the Kömürhanophiolite. They are dominated by basalt, basaltic-andesite, andesite and dacite. All the rocks of the Kömürhanophiolite originated from a tholeiitic magma. Whole rock and mineral chemistry analyses of the ophiolitic unitsindicate that the Kömürhan ophiolite was formed above an intraoceanic subduction zone.The Baskil granitoid is characterized by both mafic and felsic plutonic and subplutonic rockassociations. The mafic and felsic plutonic rocks of the Baskil granitoid contain mafic microgranular enclaves(MME) in different shape and size. Geochemically, the Baskil granitoid displays the typical characteristics of I-type, calc-alkaline plutons. Whole rock and mineral chemistry analyses of the rocks from the Baskil granitoidindicate that this magmatic unit was formed in a volcanic arc tectonic setting.The geological and geochemical studies carried out in the region suggest that: the ophiolites formedabove an intra-oceanic subduction zone between the Arabian platform to the south and the Tauride platform tothe north in Late Cretaceous. The ensimatic island arc unit formed above the SSZ-type oceanic crust at morematured stage. All the units were then accreted to the base of the Malatya-Keban platform to form the Taurideactive continental margin and intruded by the Baskil granitoid in this setting.Key words: Elazığ, Ophiolite, intra oceanic subduction zone, Baskil granitoid, Volcanic arcII