engleski

Submerged marine terraces and paleo shorelines along the eastern rim of the Mid Adriatic Deep

Submerged marine terraces provide evidence of the past sea-level fluctuations or the effect of the bottom currents. Sea-level changed significantly since the lower Pleistocene, with up to 135 m lower levels than at present. Periods of long-term sea-level stillstands possibly enabled the formation of marine terraces. The formation of the Adriatic Sea bottom currents is related to an interaction between two south-flowing water masses: the North Adriatic Dense Water in the northern Adriatic, and the Levantine Intermediate Water in the Eastern Mediterranean. Bottom-current activity can also form terraced erosional features. The investigated area is located in the central part of the eastern Adriatic, in the SW part of the Žirje island archipelago. The archipelago is characterized by steep island escarpments and submerged islands. The morphology, with almost vertical SW island shores, is typical for the outer rim of the Dalmatian islands and extends to Telašćica and Kornati archipelago. To successfully detect the distribution and characteristics of submerged marine terraces, we used high-resolution acoustic methods – Multibeam Echosounder and CHIRP Sub-bottom Profiler. The results of the detailed survey display abundant evidence of terraced landforms. The resulting landforms can be grouped into five depth-related classes with ranges 53-55 m b.s.l., 70-72 m b.s.l., 80-85 m b.s.l., 100-105 m b.s.l. and 125- 130 m b.s.l. Future investigations will provide an answer to whether studied landforms were created by former sea-level oscillations mainly during the Pleistocene falling stage systems tract, bottom current circulation, or both phenomena had a measurable effect on the formation of the submarine terraces. This work was supported by the Croatian Science Foundation in the project “QMAD” (HRZZ IP-04-2019- 8505).

Submerged terraces, sea-level fluctuations, Eastern Adriatic Sea, bottom currents, MBES, CHIRP SBP, Pleistocene

nije evidentirano