Post-glacial seasonal diatom record of the Mertz Glacier Polynya, East Antarctica

An ultra-high-resolution post-glacial laminated sediment record from Mertz Ninnis Trough, East Antarctic Margin (EAM), has been analysed using SEM backscattered electron imagery, secondary electron imagery and quantitative diatom abundance. Laminations are classified using visually dominant diatom species and terrigenous content. Four biogenic diatom ooze laminae types, one diatom-bearing terrigenous lamina type and one diatom-bearing terrigenous sub-lamina type have been identified. Diatom ooze lamina types comprise near-monogeneric Hyalochaete Chaetoceros spp. resting spore laminae, laminae characterised by Corethron pennatum, laminae characterised by Rhizosolenia spp. and mixed diatom assemblage laminae. Diatom-bearing terrigenous lamina and sub-lamina types comprise mixed diatom assemblage terrigenous laminae and sub-laminae characterised by Porosira glacialis resting spores. Formation of each of these lamina types is controlled by seasonal changes in nutrients, oceanographic regimes and the Mertz Glacier Polynya dynamics.