A micropaleontological focus on two piston cores from the Edisto Inlet, Ross Sea, Antarctica.

In the frame of the PNRA-Holoferne Project (see Tesi et al., 2019), detailed micropaleontological analyses on two gravity cores, HLF16_01 (11.4 m long) and HLF17_01 (14.6 m long), collected in the same site into the Edisto Inlet (Ross Sea, Antarctica), have been conducted. The high biosiliceous sedimentation characterising the Edisto Inlet (accumulation rates are as fast as 0.5 cm a-1, core HLF17_01 covering ca. the last 2800 years) together with its geomorphology, allowed the formation of diatom laminations, as well as their preservation in the sediment record. Therefore, studies on diatom assemblages are being conducted both on homogenized sediments (samples taken each 5 cm without considering whether one or more laminae were being collected) along the whole HLF17_01 core and on distinct laminae from section III of the same core. Preliminary results show that while diatom assemblages characterising single laminae give information on the paleo sea-ice dynamics within the inlet, whereas the whole-core-analysis is displaying the regional climate evolution in the last 3 ka of the Ross Sea. As diatom assemblages are representative of sea surface waters conditions, information such as bottom oxygenation levels and organic matter fluxes are gained from benthic foraminiferal assemblages in the twin core HLF16_01. As the two cores are visually correlated by means of laminae, we will be soon able to compare surface paleoprimary production conditions with changes in the benthic foraminiferal fossil record. Environmental investigation on the paleo sea-bottom conditions will be further enriched throughout the study of brittle stars (Class: Ophiuroidea) vertebral-arm-ossicles-accumulation-levels found in core HLF16_01. Observations of ossicles have been conducted by means of the Hitachi TM3030 Tabletop Microscope, available at the Earth Sciences Department, University of Pisa.