The Late Cenozoic evolution of the Aksu basin (Isparta Angle; SW Turkey). New insights

Abstract

The Mio-Pliocene basins around the Antalya gulf in SW Turkey developed above the Tauric Mesozoic platforms on which the Antalya nappes had been thrusted (in Late Cretaceous-Paleocene times). The closure of the initial Isparta Angle during these events (E-W compression) initiated the N-S orientation of the main structural lines, which persisted later and explains the orientation of the Aksu basin in contrast with the E-W orientation of the eastern Neo-gene Mediterranean basins. The area, and all southwestern Turkey, became emergent at the end of the Oligocene and were the site of shallow-marine carbonate deposits in the Chattian-Aquitanian, giving way to the wide Lycian basin in Burdigalian-Langhian times. The progressive emplacement of the Lycian nappes from the north over this basin provoked first its subsidence and then its emersion when the nappes attained their final position over the Bey Daglari platform in Langhian times. Coinciding, or in response to the Lycian nappes emplacement, the Aksu basin was initiated as an elongated N-S graben which was filled by thick accumulations of terrestrial and marine deposits(including coral reefs), which derived from the erosion of the Lycian allochton and its basement (Langhian?, Serravallian and Tortonian times). The syn-sedimentary tectonics : reactivation of the normal faults along the west margin of the basin, the continuous uplift of the neighbouring continental areas (beginning of the Aksu thrust), governed the geometry of the basin. As a result and due to the uplift of its northern margin, the Aksu basin migrated towards the south and in Messinian times it was reduced to a narrow gulf along the eastern margin of which the Gebiz limestones were deposited as fringing coral reefs. The age of these limestones has been debated. Our new data allow us to attribute them to the Messinian. The drastic retreat of the sea at the end of this period, provoked the erosion of large parts of the Messinian deposits and the formation of deep canyons on land and under the sea down to the Antalya abyssal plain, in which evaporites were deposited. During the Zanclean transgression, the Eskiköy-Kargi canyon was filled by coarse clastics of a Gilbert delta derived from the northern continental area following a model well known elsewhere in the Mediterranean basins. Southward, shallow-marine sands and marls unconformably cover the remnants of the Messinian deposits and the emergent areas of the southern Antalya gulf. After Zanclean times (end of Pliocene?), the Aksu basin was deformed, due to the west-directed Aksu compressional event (end of the Aksu thrust). Quaternary terraces of the Aksu river at various altitudes, as well as the terraces of the Antalya tufa can be related to sea level fluctuations.

Reconstructing the sedimentary evolution of the Miocene Aksu Basin based on fan delta development (eastern Mediterranean-Turkey)

“…b) Location and boundaries of Aksu, Köprüçay, and Manavgat basins in the Isparta Angle. Akay and Uysal, 1984;Şenel, 1997;Glover and Robertson, 1998a;Karabıyıkoğlu et al, 2004;Monod et al, 2006;Üner, 2009;Poisson et al, 2011). b) Location of the FDs in Aksu Basin.…”

“…Stratigraphic columnar section of the study area (modified from Poisson et al, 2003Poisson et al, , 2011Karabıyıkoğlu et al, 2004;Üner, 2009 Karabıyıkoğlu et al, 2004;Çiner et al, 2008;Üner, 2009 Matrix to clast-supported breccia consisting of fine to coarse-grained, poorly sorted, very angular to subrounded extraclast limestone (Figure 4a). Thin-to very thick-bedded (3-200 cm) tabular units with sharply defined flat bases and tops; occasional normal grading with red mud or carbonate matrix.…”

“…Examples from the Kasaba Basin (Hayward and Robertson, 1982) and Çatallar Basin (Koşun et al, 2009) from the southwestern Taurides are well known. Other important alluvial fan-FD complexes are observed in the Miocene Antalya Basins (Flecker et al, 1998;Robertson, 1998a, 1998b;Deynoux et al, 2005;Çiner et al, 2008;Poisson et al, 2011). For instance, Karabıyıkoğlu et al (2000) described thick alluvial fans in the Miocene Manavgat Basin.…”

“…The Aksu Basin, the subject of this study, experienced multistage tectonism (Flecker et al, 1998;Glover and Robertson, 1998b;Poisson et al, 2011;Üner et al, 2015;Koç et al, 2016) and that activity led to the formation of alluvial fan/FD bodies at the basin. An alluvial fan (Eskiköy) and five FD sequences (Kapıkaya, Kozan, Karadağ, Kargı, and Bucak FDs) play a major role in the sedimentary evolution of the basin.…”

Polyphase tectonic evolution of the Aksu Basin, Isparta Angle (Southern Turkey)

“…On the present day map, this basin consists of three subbasins, namely the Aksu, Köprüçay and Manavgat. The N-S striking Klrkkavak Fault and W-to SW-verging Aksu Thrust are the two major structures dividing these three basins (Dumont & Kerey 1975;Poisson 1977;Akay et al 1985;Monod et al 2006;Çiner et al 2008;Poisson et al 2011) (Fig. 1b).…”