Coastal uplift along the Eastern Black Sea coast: New marine terrace data from Eastern Pontides, Trabzon (Turkey) and a review

摘要

An 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.