Geodynamic significance of the Cretaceous pillow basalts from North Anatolian Ophiolitic Mélange Belt (Central Anatolia, Turkey): geochemical and paleontological constraints

Abstract

The most widespread blocks within the Cretaceous ophiolitic mélange (North Anatolian ophiolitic mélange) in Central Anatolia (Turkey) are pillow basalts, radiolarites, other ophiolitic fragments and Jurassic-Cretaceous carbonate blocks. The pillow basalts crop out as discrete blocks in close relation to radiolarites and ophiolitic units in Cretaceous ophiolitic mélange. The geochemical results suggest that analyzed pillow basalts are within-plate ocean island alkali basalts. The enrichment of incompatible elements (Nb, Ta, Light REE, Th, U, Cs, Rb, Ba, K) demonstrates the ocean island environment (both tholeiites and alkali basalts) and enriched MORB. Dated calcareous intrafills and biodetrital carbonates reveal an age span of Callovian-Early Aptian. The thin-shelled protoglobigerinids, belonging to the genus Globuligerina, in the calcareous intrafills between pillow basalt lobes indicates a Callovian-Barremian age interval, most probably, Valanginian to Late Barremian. The volcanic and radiolarite detritus-bearing orbitolinid-Baccinella biodetrital carbonates dated as Late Barremian-Early Aptian in age, were probably deposited around atolls and have a close relationship with the ocean island pillow basalts. The results collectively support the presence of a seamount on the Neo-Tethyan oceanic crust during the Valanginian-Late Barremian and atolls during the Late Barremian-Early Aptian interval. The presence of an oceanic crust older than that seamount along the Northern Branch of Neo-Tethys is conformable with the geodynamic evolution of the Tethys.

Geochemistry and origin of plagiogranites from the Eldivan Ophiolite, Çankırı (Central Anatolia, Turkey)

“…The zone starting from north of I · zmir is approximately 2000 kilometers long and continues the Sevan-Akera Zone to the northeast and Zagros-Neyriz-Oman Zone towards to the southeast (Okay & Tüysüz 1999;Tekin et al 2002). The Eldivan Ophiolite taking place in middle parts of IAESZ, represents the remnants of the Neotethyan oceanic lithosphere, which rifted in the Upper Triassic and closed in the Cretaceous-Lower Paleocene (Bailey & McCallien 1953;Akyürek 1981;Tankut 1984;Bragin & Tekin 1996;Göncüoglu et al 2003Göncüoglu et al , 2010Rojay et. al.…”

Jurassic and Cretaceous radiolarian assemblages from the Bornova mélange in northern Karaburun Peninsula (western Turkey) and its connection to the İzmir–Ankara mélanges

“…Tekin and Göncüoğlu (2007) and Tekin and Göncüoğlu (2008); (4) Tekin and Göncüoğlu (2009); (5) ; (6) Göncüoğlu et al (2000); (7) Göncüoğlu et al (2006b); (8) Yalınız et al (in prep. ) in Göncüoğlu et al (2006b); (9) Göncüoğlu et al (2006a), Göncüoğlu et al (2010) and Tekin et al (2002); (10) Servais (1982); (11) Bragin and Tekin (1996); (12) Rojay et al (2004); (13) Çelik (2010) and Üner (2010) in Tekin, Çelik et al (2012); (14) Tüysüz and Tekin (2007); (15) Boccaletti et al (1966); (16) Bozkurt et al (1997). The map is modified after Moix et al (2008).…”

“…However, Okay and Tüysüz (1999) suggest that the tectonic fabric and the scarcity of a well-defined matrix tend to consider them as tectonic mélanges, or imbricated thrust stacks, rather than real ophiolitic mélanges. The age of the blocks ranges from Carboniferous to Eocene (Çapan & Buket, 1975;Norman, 1993;Rojay, 2013;Rojay, Yalınız, & Altıner, 2001;Tüysüz, Dellaloğlu, & Terzioğlu, 1995). The final juxtaposition and imbrication between the three above-mentioned mélanges occur in the latest Cretaceous, as shown by the Maastrichtian flysch development overlying the ophiolitic mélange (Norman, 1984).…”

“…Also west of Ankara, Mekik (2000) obtained a Valanginian age from a radiolarite block in a sedimentary mélange not directly related to the ophiolitic mélange, interpreted as a slope deposit on the southern flank of the Sakarya Continent. Also, in the Ankara region (Dereköy, Karacakaya, Kalecik and Çandır), Rojay et al (2004) investigated infillings within pillow basalts showing mostly within-plate ocean island alkali basalts (OIB), with minor MORB to E-MORB signatures. Palaeontological data obtained from biodetrital limestones indicate a maximum age spectrum from Callovian to Barremian (Figure 3, no.…”

Jurassic–Paleogene intraoceanic magmatic evolution of the Ankara Mélange, north-central Anatolia, Turkey

“…We have obtained Middle-Upper Triassic and Cretaceous biostratigraphic ages from the reefal limestones overlying the seamount volcanic units, and 40 Ar/ 39 Ar whole-rock ages of 96.6 ± 1.8 Ma from the alkaline pillow lavas that are stratigraphically associated with the pink-colored pelagic limestones . Rojay et al (2004) obtained the late Barremian-early Aptian biostratigraphic ages from the reefal limestones resting on the pillow lavas with ocean island basalt (OIB) geochemical affinities. Blocks of these neritic carbonates and the underlying alkaline pillow lavas are also embedded in a turbiditic sequence consisting of chert and volcanic rock clasts in a fine-grained sandstone matrix.…”