Dust Concentration and grain size record from the Beyond EPICA oldest ice: implications for dust preservation in the oldest sections of the core.

Mineral dust concentration and grain size preserved in polar ice cores serve as critical paleoclimate proxies spanning the Holocene and Pleistocene epochs. These parameters yield valuable information about past environmental conditions in dust source regions, atmospheric dust loading and transport dynamics, exhibiting pronounced variability across glacial–interglacial cycles. The Antarctic dust deposition record derived from the ∼800.000 years old EPICA Dome C (EDC) ice core has now been extended further back into the Early Pleistocene through analysis of the Beyond EPICA-Oldest Ice Core (BEOIC). Here we present the preliminary Coulter Counter-derived dust concentration (0.6-18 μm range) and volume-size data from BEOIC for the period predating the EDC record, and compare them with available marine dust records. Dust concentration and grain size variability in the oldest ice enable the identification of glacial and interglacial periods, with characteristic size distributions showing relatively coarser particles during interglacials and finer particles during glacials.

The use of aeolian dust as a paleoclimatic proxy in ice cores assumes that englacial processes preserve the original physical and chemical signals. However, this paradigm has been partially challenged by evidence of in situ alteration processes that induce physical and geochemical (including mineralogical) modifications within the ice. The extent and nature of these processes in the BEOIC are currently under investigation. Preliminary observations are presented and compared with findings from other Antarctic ice cores (TALDICE, RICE) to evaluate the reliability of paleoclimatic signal preservation in the oldest ice sections.