2-3-Thickness of Crust and Lithosphere
Geophysical data suggest that the eastern Anatolian crust is thick
(Çınar and Alkan 2015; Pamukçu et al. 2007; Cırmık 2018; Medved et al.
2021), but the uppermost mantle below the crust is very thin because it
strongly attenuates Sn waves (Barazangi et al 2006). The Pn velocities
are also low (−7.6 km/Sn) (Türkelli et al., 2003; Sandvol et al., 2003
A; 2003 B; Zor et al.,2003; Gök et al 2003; 2007; Maden and Öztürk 2005;
Angus et al., 2015; Barazangi et al., 2006; Özaçar et al 2008; Göğüş and
Pysklywec, 2008; Biryol et al 2011; Zor 2008; Elitok and Dolmaz 2008;
Bartol et al., 2012; Warren et al 2013; Tezel et al 2013; Skobeltsyn et
al 2016; Cırmık 2018). The heat flow is high (Tezcan 1987; Tezcan and
Turgay 1989; Dolmaz et al. 2005; Ateş et al. 2005; İlkışık 1995; Bektaş
et al 2007; Bektaş 2013; Pamukçu et al 2014: Cırmık et al 2018) and the
Curie point depth is around 12-13 km below surface (Ateş et al 2005;
Bektaş 2013; Pamukçu et al 2014; Cırmık 2018).
Based on data from the East Anatolian seismic experiment, Barazangi et
al. (2006) proposed that the East Anatolian crust floats on a partly
molten asthenosphere. Almost the whole thickness of the mantle
lithosphere was removed from the overlying crust (Piromallo and Regard
2006; Barazangi et al. 2006; Gök et al. 2007; Lei and Zhao 2007: Zor et
al. 2008; Medved et al. 2021). The following mechanisms were proposed to
explain the obliteration of the lithospheric upper mantle.
1-the delamination of upper mantle (Al-Lazki et al 2003; Göğüş and
Pysklywec 2008; Biryol et al 2011; Bartol et al 2012).
2- the steepening and break-off of the subducting slab (Davies and
Blackenburg1995; Piromallo and Morelli, 2003; Piromallo and Regard 2006;
Facenna et al. 2006) Lei and Zhao 2007; Gans et al. 2009; Dilek and
Sandvol 2009; Govers and Fithcher 2016).
3-Combination of both mechanisms that are listed above (Mahatsente et
al., 2018).
The space created by the removal of the mantle lithosphere was filled
with a hot, upwelling asthenosphere or asthenospheric wedge (Şengör et
al., 2003; Piromallo and Regard 2006), which caused adiabatic
decompression. It is the hot mantle considered responsible for the high
heat flow, the consequent regional uplift, and coeval volcanism (Pearce
et al. 1990; Keskin, 2003; Piromallo and Regard 2006; Lei and Zhao,
2007; Şengör et al., 2008. Yılmaz 2017; 2019),