The Geochronology of the Ophiolitic and Granitic Rocks Observed along the Southeast Anatolian Orogenic Belt


Karaoğlan F., Akyıldız M. (Executive)

TUBITAK Project, 2007 - 2010

  • Project Type: TUBITAK Project
  • Begin Date: February 2007
  • End Date: September 2010

Project Abstract

The southeast Anatolian region records well-preserved remnants of mountain building processes along the Alpine-Himalayan orogenic belt. The evolution of this orogen initiated with the closure of the southern branch of the Neotethyan ocean that is located between the Tauride platform to the north and Arabian platform to the south since the late Cretaceous. The tectono-magmatic/metamorphic units cropping out along the orogenic belt are key elements to better understand the evolution of the southeast Anatolian orogen, along Hatay-Kahramanmaras-Malatya-Elazığ regions. These units are, structurally from top to bottom, a) metamorphic massifs, b) ophiolites, c) ophiolite-related metamorphic rocks, and d) granitoids. The southeast Anatolian ophiolites (Kızıldağ, Göksun, Berit, İspendere and K.mürhan) were dated by LA-ICP-MS zircon U-Pb and Sm-Nd. They yielded 91.7±1.9 Ma (plagiogranite) to 93.4 ±3.0 Ma (Gabbro) in Kızıldağ (Hatay), 83.1±2.2 Ma (rhyolitic lava) in Göksun (Kahramanmaraş), 84.5±3.9 Ma (Gabbro) in İspendere (Malatya), 88.7±2.3 to 87.2±3.1 Ma (Gabbro) in K.mürhan (Elazığ). The peak metamorphic conditions (granulite) of the Berit Metaophiolite is constrained as 50.6±3.1 Ma. The granitoids are of typical I-type, calc-alkaline Andean type volcanic arc plutonics. The LA-ICP-MS U-Pb zircon ages of the granitoids yielded 81.1±2.2 Ma for Esence (Kahramanmaras) and 82.0±1.2 - 84.6±1.1 Ma for the Baskil (Elazığ) localities. Four zircon ages measured from Doğansehir (Malatya) vary between 54.9±1.2 to 45.7±1.0 Ma. The Ar-Ar ages in the Baskil granitoid vary between 84.0±0.7 to 77.25±0.42 Ma. The Ar-Ar ages in the Esence granitoid vary between 85.3±7.4 to 74.1±0.29 Ma. The Ar-Ar ages of the Dogansehir granitoid vary between 54.1±0.99 to 48.3±0.3 Ma. Apatite Fission Track (AFT) samples were collected from these magmatic intrusions to find out the rate of the collision between Arabian and Tauride platforms. The ages are clustered in two groups, (a) Early-Middle Eocene and (b) Middle Oligocene. All the data shows that (i) the crystallization ages of the ophiolites are late Cretaceous in general, but display differences from one location to another, (ii) continuous magmatic activities were existed during the closure stages of Neotethyan oceanic basins in SSZ tectonic settings, (iii) the emplacement of the ophiolites were in the latest Maastrichtian, (iv) the granitoid bodies intruded after the formation of oceanic crust, (v) the northward subduction was still in progress during Eocene time and (vi) the granitoids have formed in different episodes and have individual cooling histories.