Late Holocene submerged beachrocks in the Sea of Marmara (Tekirdağ-Altınova, NW Türkiye): Revealing the tectonic uplift rate through radiocarbon dating

Beachrock formations represent a powerful paleo-environmental proxy in tectonically active coasts because they are ideal marker horizons for reconstructing past sea-level positions and revealing vertical uplift rates. In this study, beachrocks from the Tekirdağ-Altınova coastal area were used to model the evolution of the late Holocene coastline in the northern Sea of Marmara.

As the Tekirdağ-Altınova coastal area is located in the tectonically active western Marmara region, this study aimed to investigate the role of tectonic processes in the late Holocene evolution of the coastal landscape in the study area by assessing long-term vertical deformation rates. To document and estimate coastal uplift, lesser known submerged beachrocks within the nearshore coastal area of the northern Sea of Marmara were analyzed with novel laser ablation (LA)–accelerator mass spectrometry (AMS) and standard ¹⁴C-AMS techniques and correlated with late Holocene sea level variations. The preservation state of these beachrocks allowed for their identification and mapping through the use of an unmanned aerial vehicle (UAV) equipped with a high-resolution (5 cm) camera, followed by sampling via the coring method.

The determined ages of marine shells and calcite cements from selected samples of submerged beachrock span between 2.6 and 13.6 ky BP. These ages could be correlated with the late Holocene sea-level highstand and were used to estimate the long-term uplift rate. Based on these findings, an uplift rate of approximately 0.56–0.79 mm/yr over the last 6500 years has been suggested for the area studied.