Diatoms of the McMurdo ice shelf, Antarctica: Implications for sediment and biotic reworking

摘要: Abstract In the course of investigations origin McMurdo Ice Shelf (MIS), we analyzed diatoms in 59 sediment samples collected from its upper surface. Fragments centric marine species, most which occur Ross Sea today, were found all samples, but identifiable taxa dominated total diatom flora only two samples. contrast, non-marine are abundant and diverse MIS These species probably live numerous melt ponds distributed widely over shelf surface during warmest few weeks each austral summer. Non-marine clustered four assemblages, related a complex way to geographic position on ice shelf, age, local geochemical variations, seasonal blooms. The presence sediments is consistent with isotopic evidence that consists frozen seawater, Debenham's hypothesis transport macrofossils accomplished by freezing at base upward movement through caused melting. combined floras suggest new mechanism explain mixed sediments, observed antarctic cores. composite may be introduced or reintroduced environment summers water streaming off front crevasses. Additionally, icebergs calved release theie load biota when they melt. observations pertain oher present former shelves characterized ablation basal freezing.