Coastal Uplift along the Eastern Black Sea Coast: New Marine Terrace Data from Eastern Pontides, Trabzon (Turkey) and a Review

Abstract

International audienceAn emerged, Quaternary, marine terrace sequence has been investigated near Trabzon, Turkey, along a 20-km-long stretch of the coast of the southeastern Black Sea. The sequence includes seven principal marine terraces. The terraces are frequently compound and include up to three second-order marine terraces. The upper shoreline angles of the main terraces were found at the following maximum elevations above mean sea level: 3 ± 0.5 m (TH), 12 ± 3 m (T1), 36 ± 2 m (T2), 79 ± 9 m (T3), 120 ± 3 m (T4), 138 ± 10 m (T5), and 260 ± 25 m (T6). Fossil bivalves and gastropods from the TH, T1, T2, and T3 deposits have been dated by Electron Spin Resonance (ESR). The results show that the ages of the deposits from the TH, T1, T2, and T3 terraces are 5.141 ± 0.294 ka, 124.8 ± 26.0 ka, 292.5 ± 49.8 ka, and 407.998 ± 67.475 ka, respectively. Consequently, we correlate TH, T1, T2, and T3 to marine isotope stage (MIS) 1, 5e, 9, and 11, which correspond to 5, 123, 321, and 400 ka highstands, respectively. Estimated uplift rates deduced from the elevations of T1, T2, and T3 are 0.07 ± 0.05, 0.10 ± 0.02, 0.17 ± 0.03 mm/y or m/ka. These results show nonsteady, long-term uplift rates. Extrapolation of the oldest uplift rate (i.e., determined on the highest dated terrace) shows that in the region of Trabzon, Turkey, coastal, positive, vertical deformations are recorded at 2 Ma, which corresponds to the extrapolated age of the highest terrace in the sequence. Comparison with other sequences on the Black Sea coast reveals a rather weak uplift in this zone, which can be considered significative for the recent uplift of the Eastern Pontides

Coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the Quaternary and Neogene

“…Although Middle and Upper Pleistocene as well as Holocene shorelines (MIS 11 onwards) are well documented, little attention has been devoted to the upper parts of these sequences, in particular, with respect to the genesis of compound paleocoasts (as for example in Keskin et al, 2011), rasas (see Guilcher, 1974;Pedoja et al, 2006a,b;Regard et al, 2010) and strandflats (Guilcher et al, 1986) (Fig. 2).…”

“…El Asmar, 1997), on the coast of Peru and Ecuador (Pedoja et al, 2006b,c;Regard et al, 2010), Barbados (e.g. Muhs, 2001), on the south coast of the Black Sea in eastern Turkey (Keskin et al, 2011), on the island of Sumba in Indonesia (Boekschoten et al, 1989;Pirazzoli et al, 1993;Bard et al, 1996) in Southern Spain (e.g. Zazo et al, 2003), the Azores, on the island of Flores (Azevedo and Portugal Ferreira, 1999), on the west coast of North America (e.g.…”

Arc magmatism as a window to plate kinematics and subduction polarity: Example from the eastern Pontides belt, NE Turkey

“…In addition, recent geological, geophysical Eyuboglu et al, 2007;Eyuboglu, 2010;Eyuboglu et al, 2010a). and GPS data, as well as the launching of petroleum exploration offshore of Trabzon, Rize, and Hopa imply that an active collision system extends from Georgia into the eastern Black Sea shelf area along the Rize-Trabzon-Ordu line (Turkish Petroleum Corporation web page; Bektaş and Eyuboglu, 2003;Keskin et al, 2010). The existence of a south-dipping reverse fault system along the entire length of the southern coast of the Black Sea supports a southward subduction model for the origin of the eastern Pontides orogenic belt and late MesozoiceCenozoic magmatism.…”

Geomorphic evidence for active tectonic deformation in the coastal part of Eastern Black Sea, Eastern Pontides, Turkey

“…Continuously changing landforms by tectonic processes can be overprinted by tectonic structures in a drainage basin. The coastal region of the Eastern Pontides shows geologic and geomorphologic indications suggestive of significant regional tectonic activity since Cenozoic times (Keskin, Pedoja, & Bektaş, 2011;Softa, Spencer, Emre, Sözbilir, & Turan, 2017). The aim of tectonic geomorphology is quantifying the geomorphic response of the landscape to the interaction between active tectonic and geomorphic processes (Mayer, 1986).…”