Petrological features of toung volcanics at the nortwestern part of Elazığ

IV ABSTRACT Ph. D. Thesis PETROLOGİCAL FEATURES OF YOUNG VOLCANİC-AT THE NORTWESTERN PART OF ELAZI? Sevcan KÜRÜM Fırat University Gradute School of Science and Technolog Department of Geological Engineering 1994, Page: 107 The study area is situated between Pertek and Çemişgezek townships of Tunceli province, north - northwest of Elazığ, in Eastern Turkey. In this area Cenozoic volcanites, of which petrogaphy, petrology and geochemistry are the subjects of this study, cover large areas. The lithological units of the studied area are (in chronological order); Permo- Carboniferous Keban Metamorphics, Upper Cretaceous Yüksekova Complex, Middle Eocene - Upper Oligocene Kırkgeçit Formation, Lower Miocene Alibonca Formation and Upper Miocene-Pliocene Karabakir Formation. Keban Metamorphics are marble and amphibole schist in the study area and their contacts with Yüksekova Complex are either tectonic ore intrusive in nature. Yüksekova Complex is mainly made of diorite, quartz diorite and microdiorite. However, gabbro, alkali granite and tonalite are also present in the Complex. Along intrusive type contacts, skarn formations are quite common.Karabakır Formation overlies Alibonca Formation which is one of the youngest sedimentary sequence in eastern Anatolia, with an angular uncomformity. Karabakır Formation is differentiated as volcanoclastites, lava flows and lacustrine limestones. The volcanoclastites of the studied area are composed of epi and pyroclastics what show horizantal and vertical transitions to each other. The petrographic studies show that lava flows have andesite, basalt and andesitic tuff compositions and tuffs are gradations between volcanoclasts and andesite-basalts. The lacustrine limestones grades into volcanites of Karabakır Formation, vertically and horizontally and cover limited areas in the studied area. The geochemical investigations on lava flows indicate that they are of sialic origin, their K contents vary betwen medium to high, intermediate and asidic members are calcalkalen and the basic ones are theoolitic. KEY WORDS: Karabakır Formation, volcanoclastic, lava flows, epiklactic, pyroclastic, calcalkalen, theoolitic, sialic.