부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tecto.2008.08.011 Byline: Tamer RizaoAlu (a), Osman Parlak (b)(c), Volker Hock (d), Friedrich Koller (e), Willis E. Hames (f), Zeki Billor (f) Keywords: Southeast Anatolia; Andean type margin; Granitoid; Baskil;.sup.40Ar/.sup.39Ar Geochronology Abstract: The Southeast Anatolian Orogen resulted from collision of the Afro-Arabian and the Eurasian plates following the Cretaceous to Miocene closure of the southern Neotethyan oceanic basin. In this orogenic belt, there are number of tectonomagmatic/stratigraphic units in the KahramanmaraA-Malatya-ElaziA region that are important to understand the geological evolution of southeast Anatolia during the Late Cretaceous. These are (a) metamorphic massifs (i.e. Malatya-Keban platform), (b) ophiolites (i.e. Goksun, A[degrees]spendere, Komurhan), (c) ophiolite-related metamorphics (i.e. Berit metaophiolite) and (d) granitoids (i.e. Goksun, DoAanAehir and Baskil). The Baskil granitoid crops out to the northwest of ElaziA and is a large magmatic body (170 km.sup.2) that intruded all of the above-mentioned units during Late Cretaceous time. The Baskil granitoid comprises both mafic and felsic plutonic/sub-plutonic rock associations. The felsic plutonic phase includes granite, granodiorite, tonalite and quartz monzonite whereas the felsic sub-plutonic phase is characterized by aplite, granophyre, granite porphyry and granodiorite porphyry. The granite and granodiorite contain mafic microgranular enclaves (MME). The mafic plutonic phase comprises gabbro, diorite, quartz diorite, whereas the mafic sub-plutonic phase is represented by diabase, microdiorite, quartz microdiorite, diorite porphyry, quartz diorite porphyry and dykes of orbicular gabbro dyke. Geochemically, the Baskil granitoid rocks have I-type, metaluminous-peraluminous calc-alkaline characteristics. The REE- and ocean ridge granite-normalized multi-element patterns and tectonomagmatic discrimination diagrams, together with biotite geochemistry suggest that the granitoids were formed in a volcanic arc setting. The.sup.40Ar/.sup.39Ar geochronology of the granitoid rocks yielded biotite ages of 81.9[+ or -]0.7 Ma and 81.5[+ or -]0.8 Ma (95% confidence level). Coexisting hornblende, and hornblende from additional samples, yielded ages ranging from 84.0[+ or -]0.7 Ma to 81.5[+ or -]1.1 Ma. The ophiolites are believed to have formed in a suprasubduction zone tectonic setting, whereas the ophiolite-related metamorphic rocks formed either during the initiation of intraoceanic subduction or later-stage thrusting ([approximately equal to]90 Ma). These units were then thrust beneath the Malatya-Keban platform during the progressive closure of the southern Neotethys. This was followed by intrusion of the granitoids (85-82 Ma) along the Tauride active continental margin of the southern Neotethys. Author Affiliation: (a) KahramanmaraA Sutcu A[degrees]mam Aniversitesi, Jeoloji MuhendisliAi Bolumu, 46100 KahramanmaraA, Turkey (b) Aukurova Aniversitesi, Jeoloji MuhendisliAi Bolumu, 01330 Balcali, Adana, Turkey (c) Adiyaman Aniversitesi, Mesleki ve Teknik EAitim Fakultesi, 02040 Adiyaman, Turkey (d) University of Salzburg, Department of Geology and Geography, A-5020 Salzburg, Austria (e) University of Vienna, Center for Earth Sciences, A-1090 Vienna, Austria (f) Auburn University, Department of Geology and Geography, Auburn, Alabama 36849, USA Article History: Received 3 January 2008; Revised 14 July 2008; Accepted 7 August 2008