Whole-rock and mineral chemistry of cumulates from the Kızıldağ (Hatay) ophiolite (Turkey): clues for multiple magma generation during crustal accretion in the southern Neotethyan ocean

Abstract

The late Cretaceous Kızıldağ ophiolite forms one of the best exposures of oceanic lithospheric remnants of southern Neotethys to the north of the Arabian promontory in Turkey. The ultramafic to mafic cumulate rocks, displaying variable thickness (ranging from 165 to 700 m), are ductiley deformed, possibly in response to syn-magmatic extension during sea-floor spreading and characterized by wehrlite, olivine gabbro, olivine gabbronorite and gabbro. The gabbroic cumulates have an intrusive contact with the wehrlitic cumulates in some places. The crystallization order of the cumulus and intercumulus phases is olivine (Fo86–77)± chromian spinel, clinopyroxene (Mg#92–76), plagio-clase(An95–83), orthopyroxene(Mg#87–79). The olivine, clinopyroxene, orthopyroxene and plagioclase in ultramafic and mafic cumulate rocks seem to have similar compositional range. This suggests that these rocks cannot represent a simple crystal line of descent. Instead the overlapping ranges in mineral compositions in different rock types suggest multiple magma generation during crustal accretion for the Kızıldağ ophiolite. The presence of high Mg# of olivine, clinopyroxene, orthopyroxene, and the absence of Ca-rich plagioclase as an early fractionating phase co-precipitating with forsteritic olivine, suggest that the Kızıldağ plutonic suite is not likely to have originated in a mid-ocean ridge environment. Instead the whole-rock and mineral chemistry of the cumulates indicates their derivation from an island arc tholeiitic (IAT) magma. All the evidence indicates that the Kızıldağ ophiolite formed along a slow-spreading centre in a fore-arc region of a suprasubduction zone tectonic setting.

Geochemical characteristics of ophiolitic rocks from the southern margin of the Sivas basin and their implications for the Inner Tauride Ocean, Central-Eastern Turkey

“…The major (Al 2 O 3 , MgO, CaO) and trace (Ni, Cr, Co, Sr) element geochemistry of gabbroic cumulates suggest that olivine, spinel, clinopyroxene and plagioclase fractionation played an important role within a magma chamber during their genesis at the base of an intra-oceanic arc setting. Similar features were reported from the cumulate rocks of the Mersin, Pozantı-Karsantı, Kızıldağ (Hatay) and Tekirova (Antalya) ophiolites (Bağcı, Parlak, & Höck, 2005;Bağcı et al, 2006;Parlak et al, , 2000Parlak et al, , 2002. The pyroxenite dyke cutting the mantle tectonite is characterized by low contents of TiO 2 (.05 wt%), LIL and high-field strength (HFS) elements, whereas it is rich in Ni (134.5 ppm), Cr (.42 wt.%), MgO (20.37 wt.%) and CaO (20.04 wt.%) ( Table 1).…”

U–Pb and Sm–Nd geochronology of the ophiolites from the SE Turkey: implications for the Neotethyan evolution

“…These are; (a) the Mid-Late Triassic rifting to spreading of Southern Neotethys, separated from North Africa (Gutnic, Monod, Poisson, & Dumont, 1979;Robertson & Woodcock, 1979;1980;Şengör, Satır, & Akkök, 1984;Yılmaz, 1993;Yılmaz et al, 1993), (b) Late Cretaceous northward subduction-accretion of ophiolites and arc-related units (Bağcı et al, 2005;2008;Karaoğlan, Parlak, Kloetzli, Thöni, et al, 2013;Karaoğ-lan, Parlak, Kloetzli, Koller, et al, 2013;Robertson, 2002Robertson, , 2004Robertson et al, 2006Robertson et al, , 2007Robertson et al, , 2012Rizaoğlu et al, 2006;2009;Parlak et al, 2004;2009, (c) Mid-Eocene subductionrelated extension (Robertson et al, 2006;Yılmaz, 1993;Yiğitbaş & Yılmaz, 1996a, 1996bKaraoğlan, Parlak, Robertson, et al, 2013) and (d) Early-Middle Miocene collision and southward thrusting over the Arabian Foreland Robertson et al, 2006Robertson et al, , 2007Robertson et al, , 2012Şengör & Yılmaz, 1981;Yılmaz, 1993).…”

“…The age of the blocks ranges from Senonian to Campanian (Aslaner, 1973;Atan, 1969). The Kızıldağ ophiolite displays a complete oceanic lithospheric remnants and is represented by mantle tectonites, ultramafic to mafic cumulates, isotropic gabbro, sheeted dikes, plagiogranites and a volcanic complex at the top (Figures 2 and 3) (Bağcı et al, 2005(Bağcı et al, , 2008Dilek & Delaloye, 1992;Dilek & Thy, 2009;Selçuk, 1981;Tinkler, Wagner, Delaloye, & Selçuk, 1981). The mantle tectonites, having over 3 km thickness and intruded by pegmatitic gabbroic and pyroxenitic dikes, are represented primarily by harzburgite with local lenses and bands of dunite (Bağcı, 2004;Dilek & Thy, 1998, 2009Erendil, 1984;Tekeli, Whitechurch, & Erendil, 1983;Tinkler et al, 1981).…”

“…They are characterized by dunite, wehrlite, olivine gabbro, olivine gabbronorite and gabbro (Bağcı, 2004). Bağcı et al (2005) documented that the cumulate rocks were derived from island arc tholeiitic (IAT) magma. The isotropic gabbroic rocks with 2-2.5 km thickness are dominant in the upper part of the plutonic section and are represented by gabbro, diorite and quartz-diorite rock assemblages (Pişkin et al, 1990;Selçuk, 1981;Tinkler et al, 1981).…”

“…The sheeted dikes are mainly oriented along a strike Figure 2. Generalized log sections of the SE Anatolian ophiolites (Bağcı et al, 2005;Parlak et al, 2013bParlak et al, , 2004Beyarslan & Bingöl, 1991;Rızaoğlu et al 2009). (Dilek & Thy, 1998;Selçuk, 1981).…”