Quaternary Sedimentary Environments within an active rift zone basin The Alkyonides Gulf, Corinth Rift, Greece.

Abstract

Continental rifting plays an essential role in forming the ocean basins and creates the active rift zones with high geohazard potential. The environments of active rift basins are formed by combined tectonic activity, sedimentary processes, and climate and sea-level changes. The Corinth Rift has one of the higher levels of seismicity in the world and with extension rates up to 10-20 mm/year, it is also young, forming ~5 Ma, and with a simple tectonic history and high sedimentations rate. The Alkyonides Gulf is located on the eastern part of Corinth rift, and is characterized by dominant active faulting on the southern margin. The primary factors that influence sedimentary/basin environment through time are fault subsidence, sediment compaction, global sea-level change, timing of faulting activity and the heights of basin boundaries. The International Ocean Discovery Program (IODP) Expedition 381 in 2017 drilled and cored at three sites, including Site M0080 in the Alkyonides Gulf used in this study. The environments in Units 1 and 2 are alternating marine and isolated/lake (with shallow marine at base of unit 2), Unit 3 is terrestrial, and Unit 4 is a shallow subaqueous basin. The preliminary results which are the totals of accommodation space created for each of the units is 295 m in unit 1, 475 m in unit 2, 1175 m in unit 3 and 250 m in unit 4. Faults subsidence was the dominant factor, but longer-term fault activity is important. Units 1-3 environments can generally be explained from the calculations, but for unit 4, the factors cannot fully explain. However, there are additional factors, such as the sills boundary that may contribute.