Repeated advance and retreat of the East Antarctic Ice Sheet on the continental shelf during the early Pliocene warm period

摘要: Abstract Diatom analysis of a sediment core recovered at IODP Site U1358 on the continental shelf off Adelie Coast indicated that lower section contained an assemblage dating back to Thalassiosira innura Zone Pliocene ranges from 4.2 5.12 Ma. Based lithological descriptions both macro- and micro-scale this early part core, four facies were interpreted diamictons representing progressive advance retreat grounding line over site. Facies 1a 1b contain distinct directional signal orientation a-axis clasts with several phases fabric development along brittle ductile deformation features are common in sediments have been subglacially deformed. 1c 1d finely laminated deposited open marine conditions. The within depositional model provide for first time direct evidence ice advancing across adjacent Wilkes Subglacial Basin least occasions separated by three periods conditions indicating grounded inland site during warmer than present Pliocene. times correlated previous findings neighbouring rise sites also oscillating margin. This has significant implications because firstly it suggests dynamic East Antarctic Ice Sheet (EAIS) is probably far more sensitive climatic oceanic forcing even relatively short had previously thought. Secondly proxies used interpret can be linked migration shelf. It important future behaviour sensitivity EAIS under continuing warming Together results rise, paper provides crucial extent target new sheet region