The Initiation of the Neotectonic era in Eastern Turkey: Evidence from Apatite Fission Track Geochronology


KARAOĞLAN F. , PARLAK O. , HEJL E., KOP A.

12th International Conference on Thermochronology, Glasgow, Scotland, 16 - 20 August 2010, pp.295

  • Publication Type: Conference Paper / Summary Text
  • City: Glasgow
  • Country: Scotland
  • Page Numbers: pp.295

Abstract

14 samples collected from the magmatic intrusions along some 400 km of the East Anatolian
Fault Zone (EAFZ) to find out the initiation and vertical movements of the East EAFZ. The magmatic intrusions are located from west to east in Esence (Kahramanmaraş), Doğanşehir
(Malatya) and Baskil (Elazığ) and formed at Late Cretaceous (Esence & Baskil) and Middle
Eocene (Doğanşehir) time span in an arc setting.
The apatite seperates were counted by populated grain method (PGM). The ages are
clustered in two age groups, (i) Early-Middle Eocene and (ii) Middle Oligocene whereas one
distinct sample yields 16.8±1.8 Ma. The cooling models made from track length (TL) and
age data indicates that these apatite FT ages yield mix ages, whereas three cooling time span
from crystallization to unroofing of the granitoids occurred in the region. First cooling phase
is Late Cretaceous observed in Esence and Baskil granitoids interpreted as the continuous
cooling of the granitoids after a shallow emplacement. Second phase is Early to Middle
Eocene time span observed in all granitoids interpreted as the continuous cooling of the
Doğanşehir granitoid and uplift of the Esence & Baskil granitoids with a high uplift rate
during an opening of a back arc basin in the region. The last phase is the Late Middle to Late
Miocene time observed in all intrusions interpreted as the initiation & movement of the
EAFZ. The 16.8±1.8 Ma age data collected on the fault zone interpreted as resetting by
frictional heating during faulting.
During the closure of the Neo-Tethyan Ocean at Late Cretaceous, the subduction under
Tauride platform led to the formation of the arc magmatism. This magmatism formed the
Essence granitoid to the west and Baskil granitoid to the east. The emplacements of these
intrusions were shallow where the cooling was steadily continues at Late Cretaceous. During
Early to Middle Eocene (50-40 Ma) continues subduction & accretion led to the opening of a
back-arc basin in the region and the Doğanşehir granitoid formed to a very shallow depth
(~5-7 km), whereas other granitoids uplifted and cooled through ~60 °C. At the Middle to
Late Miocene time span, the East Anatolian Fault Zone developed. The EAFZ and related
structures tilted & denudated the region, which led to the unroofing of the granitoids from
Serravallian to Messinian.