An influence of the Antarctic bottom water currents on the formation of the upper sediment cover in the Vema Fracture Zone, Central Atlantic

The DSDP holes 26/353 have been drilled in the central part of the Vema Fracture Zone (VFZ) to investigate the sediment infilling, however, the upper 96 m of the sediments were not sampled. Therefore, the age and character of the uppermost sediments at a water depth of > 5 km remain unknown. During the cruises 60 and 65 of the RV Akademik Ioffe in 2021 and 2023, respectively, the high-resolution sub-bottom profiling (SBP) and coring of the uppermost sediment cover at DSDP site 26/353 location have been conducted to address the sediment age and origin, as well as the mean sedimentation rates. The results of sub-bottom profiling demonstrate an alternation of acoustically transparent and stratified units reflecting cyclic changes in sedimentation mode. Grain size and microfossil data from three sediment cores, supplemented by the AMS-¹⁴C dating support an assumption on the contourite and turbidite-contourite origin of the upper transparent sediment layer, represented by terrigenous mud and underlying the postglacial mainly pelagic calcareous cap. Our results suggest the eastward transport of terrigenous, commonly turbiditic, sediments by the Antarctic Bottom Water (AABW) and their transformation into contourites along the Vema valley.