Paleobathymetric Evolution of the Miocene Deposits of the Gömbe Sector of the Lycian Foreland and Aksu Basins in Antalya, Turkey
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Turkish Journal of Earth Sciences Turkish J Earth Sci (2020) 29: 649-663 http://journals.tubitak.gov.tr/earth/ © TÜBİTAK Research Article doi:10.3906/yer-1906-3 Paleobathymetric evolution of the Miocene deposits of the Gömbe sector of the Lycian Foreland and Aksu basins in Antalya, Turkey 1, 2 3 1 Fatih Seçkin ŞİŞ *, Tanja KOUWENHOVEN , Ayten KOÇ , Nuretdin KAYMAKCI 1 Department of Geological Engineering, Middle East Technical University, Ankara, Turkey 2 Willem C. van Unnikgebouw, Heidelberglaan 2, Utrecht, The Netherlands 3 Department of Geological Engineering, Yüzüncü Yıl Üniversitesi, Van, Turkey Received: 05.06.2019 Accepted/Published Online: 27.03.2020 Final Version: 05.05.2020 Abstract: The evolution of the Lycian Foreland and Aksu basins are associated with the Africa-Eurasia convergence and collision of intervening continental blocks. Both basins developed around the Beydağları, a Mesozoic carbonate platform, which constitutes the main component and western limb of the Isparta Angle. The Gömbe Basin is an integral part of the Lycian Foreland Basin that comprises mainly Eocene to Late Miocene turbidites, onto which the allochthonous Lycian and Antalya nappes thrust over. The Aksu Basin, however, developed in the inner part of the Isparta Angle and is bounded by the Aksu Thrust in the east. During their evolution, these basins experienced significant bathymetric changes, possibly due to vertical motions and variations in the sediment supply. This study provides a detailed analysis of the paleobathymetric evolution of these basins. This conducted paleobathymetric study was based on the determination of the depositional depth by the abundance ratio of planktonic versus benthic foraminifera, which is the function of the water depth. The percentage of planktonic foraminifera relative to the total foraminifer population (%P) increases from shallow to deep water. However, some benthic foraminifera species are directly affected by the oxygen level of the bottom water, rather than by paleobathymetry, i.e. stress markers, and were discarded in the calculation. Additionally, the dissolution of the foraminifera has the potential for miscalculations, since planktonic foraminifera are more prone to dissolution than benthic ones. Nevertheless, the obtained quantitative results were verified and validated qualitatively by specific benthic depth markers that lived at specific depth ranges. Aksu Basin had a shallowing trend, and the sedimentation rate exceeded the subsidence in the middle of the section. Calculated depths for the Gömbe Basin indicated depths around 1000 m, which was contrary to the high sedimentation rates indicated by the turbiditic facies of the basin infills. Keywords: Foraminifera, paleobathymetry, Lycian foreland Basin, Aksu Basin, Isparta Angle 1. Introduction The Antalya Basin comprises 3 subbasins, namely the Aksu, Throughout the Cenozoic Era, convergence between Köprüçay, and Manavgat basins, which are located in the Africa and the Eurasian plate led to the gradual closure of eastern part of the Beydağları Platform (Akay et al., 1985; the Neotethyan oceanic basins, and resulted in the present Flecker et al., 1998; Glover and Robertson, 1998; Poisson tectonic scheme of the eastern Mediterranean region. The et al., 2003a; 2011; Flecker et al., 2005). These basins are Aegean and Cyprus arcs, 2 subduction systems, appeared associated with the evolution of the Central Taurides (Gutnic in the eastern Mediterranean. The Isparta Angle is defined et al. 1979; Özgül, 1984) and developed in response to the as a junction of these morpho-tectonic structural units development of the Isparta Angle and Aksu Thrust. The (Blumenthal, 1963). The Antalya Basin, located within Lycian nappes thrust from the northwest and the Tauride the Isparta Angle, was formed on the Mesozoic (para) from the east on the Beydağları platform. Aside from the autochthonous carbonate platform in the western Taurides. Lycian Nappes, the emplacement of the Antalya and Alanya Terminal closure of the Neotethyan Ocean signified the Nappes placed a distinct unit within the Isparta Angle deformation history from Mesozoic to Early Cenozoic, (Figure 1). The Lycian Foreland Basin began to develop in which comprised thrusting of the Lycian Nappes and the Early Miocene, and it was under a compressional regime associated ophiolitic units over the Beydağları and Geyikdağı due to thrusting of the Lycian Nappes over the Beydağları paraautochthonous units (Dumont et al., 1972; Özgül, 1976, Platform toward the Langhian (Flecker et al. 1998; Poisson 1984; Poisson et al., 2003a; Van Hinsbergen et al., 2010). et al., 2003b; Flecker et al., 2005; Poisson et al., 2011). * Correspondence: [email protected] 649 This work is licensed under a Creative Commons Attribution 4.0 International License. ŞİŞ et al. / Turkish J Earth Sci Figure 1. Major tectonic units and Neogene sedimentary basins in the Isparta Angle (modified from Kaymakcı et al., 2018). Miocene to Pliocene stratigraphy and kinematic The geometry, facies distributions, paleobathymetry, evolution of the Antalya and Lycian Foreland basins have and environment of deposition were mainly controlled by been studied in detail by various researchers (e.g. Özgül, tectonic regimes, as well as global sea level fluctuations. 1976; Hayward and Robertson, 1982; Hayward, 1984; Akay Paleobathymetric studies have provided important insight et al., 1985; Çiner et al., 2008). The earliest biostratigraphic into understanding the development of the accommodation studies in the region were conducted by Bizon et al. (1974) space, sediment supply, and interplay between tectonics and Gutnic et al. (1979). They were followed by İslamoğlu and sedimentation (Allen and Allen, 1990). In this context, (2001), İslamoğlu and Taner (2002, 2003), Poisson et al. the main purpose of this contribution was to understand (2003b), Şenel (2004), and Sagular (2009), and included the paleobathymetric evolution of the Aksu and Gömbe planktonic foraminifera, nannoplanktons, molluscs, sector of the Lycian Foreland Basin using the change and corals. Tectonic evolution and paleoenvironmental in the ratio of planktonic versus benthic foraminiferal characteristics of the region were addressed by Akay and present within the infills of these basins. This will shed Uysal (1988), Flecker et al. (1998), Glover and Robertson some important light on the development history of these (1998), Flecker et al. (2005), Karabıyıkoğlu et al. (2005), basins, especially on how the accommodation space and Poisson et al. (2011), Üner et al. (2015), and Koç et water depth changed during emplacement of the Lycian al. (2016). However, no published studies exist on the Nappes from the west and the Antalya Nappes along paleobathymetric evolution of these basins, in terms of the Aksu Thrust Fault from the east over the Beydağları changes in the accommodation space and vertical block Platform during the Neogene. The evolution of the basins movements in the region. is closely linked with the Africa-Eurasia convergence and 650 ŞİŞ et al. / Turkish J Earth Sci collision of intervening continental blocks (Flecker et al., onto the Beydağları Platform. However, the Gömbe sector 2005; Çiner et al., 2008; Üner et al., 2015; Koç et al., 2016). of the Lycian Foreland Basin developed progressively on Therefore, the information obtained from these basins the Beydağları Platform, as the Lycian Nappes advanced will provide constraints on the evolution of the eastern eastwards and thrusted over the Beydağları platform Mediterranean basins over the last ~15 my. from the west during the Eocene to Middle Miocene (Hayward, 1984). The Beydağları Platform, together with 2. Geological setting the Geyikdağı Unit, constitutes the central axis of the Convergence between African and the Eurasian plates Taurides, since they are structurally the lowest units in resulted in partial closure of the different branches of the belt. They are considered as paraautochthonous units the Neotethyan oceanic basin. The southern Aegean and comprise thick Mesozoic carbonates spanning from and Cyprus arcs are 2 subduction systems along which the Paleozoic to Late Cretaceous. Carbonate deposition on the oceanic crust at the northern edge of the African the Beydağları Platform continued until the Early Miocene Plate, which constitutes the remnant oceanic crust of the in various places (Hayward, 1984). The Alanya Nappes eastern subducting below Anatolia at the southern edge contain Permian and Triassic high-pressure metamorphic of Eurasia. Various slab-edge processes during the Late rocks with peak metamorphism that took place around Cretaceous and onwards gave way to the formation and the Santonian and was characterized by eclogite to total destruction of various sedimentary basins on the blueschist facies rocks overprinted by younger medium- overriding plate. The remnants of these basins are exposed grade greenschist facies metamorphism (Çetinkaplan et partly in various locations in southwestern Anatolia. al., 2016). The Antalya Nappes contain various volcanic These basins include very thick Eocene to recent marine, and volcaniclastic rocks, ophiolitic fragments belonging to continental deposits (Hayward and Robertson, 1982; to different depths of an oceanic crust, as well as various Hayward, 1984; Glover and Robertson, 1998; Flecker et sedimentary units belonging to different tectonic and al., 2005; İşler et al., 2005; Alçiçek et al., 2006 and 2013; depositional environments. This is typical for colored Faccenna et al.,