Geodynamic significance of granitoid magmatism in the southeast Anatolian orogen: geochemical and geochronogical evidence from Goksun-Afsin (Kahramanmaras, Turkey) region


Parlak O.

INTERNATIONAL JOURNAL OF EARTH SCIENCES, cilt.95, ss.609-627, 2006 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 95 Konu: 4
  • Basım Tarihi: 2006
  • Doi Numarası: 10.1007/s00531-005-0058-2
  • Dergi Adı: INTERNATIONAL JOURNAL OF EARTH SCIENCES
  • Sayfa Sayıları: ss.609-627

Özet

In southeast Anatolia, there are number of tectonomagmatic units in the Kahramanmaras, - Malatya - Elazig. region that are important in understanding the geological evolution of the southeast Anatolian orogenic belt during the Late Cretaceous. These are ( a) metamorphic massifs, (b) ophiolites, ( c) ophiolite-related metamorphics and (d) granitoids. The granitoids (i.e. Goksun-Afsin in Kahramanmaras, Dogansehir in Malatya and Baskil in Elazig) intrude all the former units in a NE - SW trending direction. The granitoid in Goksun-Afsin ( Kahramanmaras,) region is mainly composed of granodioritic and granitic in composition. The granodiorite contains a number of amphibole-bearing mafic microgranular enclaves of different sizes, whereas the granite is intruded by numerous aplitic dikes. The granitoid rocks have typical calcalkaline geochemical features. The REE- and Ocean ridge granite-normalized multi-element patterns and tectonomagmatic discrimination diagrams, as well as biotite geochemistry suggest that the granitoids were formed in a volcanic arc setting. The K - Ar geochronology of the granitoid rocks yielded ages ranging from 85.76 +/- 3.17 to 77.49 +/- 1.91 Ma. The field, geochemical and geochronological data suggest the following Late Cretaceous tectonomagmatic scenario for southeast Anatolia. The ophiolites were formed in a suprasubduction zone tectonic setting whereas the ophiolite-related metamorphic rocks formed either during the initiation of intraoceanic subduction or late-thrusting ( similar to 90 Ma). These units were then overthrust by the Malatya - Keban platform during the progressive elimination of the southern Neotethys. Thrusting of the Malatya - Keban platform over the ophiolites and related metamorphic rocks was followed by the intrusion of the granitoids ( 88 - 85 Ma) along the Tauride active continental margin in the southern Neotethys.