Changing Oligocene climate recorded by palynomorphs from two glacio-eustatic sedimentary cycles, Cape Roberts Project, Victoria Land Basin, Antarctica

摘要: Abstract Two marine palynomorph assemblages recovered from two glacio-eustatic sedimentary cycles the Cape Roberts Project (CRP), which over 1500 m of Oligocene and Miocene strata western margin Victoria Land Basin, are investigated. We present results one cycle dated as early other late Oligocene. Modest numbers palynomorphs were recovered, with an average abundance 56 specimens per gram. The both broadly similar, dominated by acritarchs phycoma prasinophyte algae. These include Leiosphaeridia sp. 2, 3, alga, Cymatiosphaera 2. In detail, however, lower assemblage is different that upper includes Impagidinium cf. dispertium elegans. 6 Pyxidinopsis abundant. characterized absence (?) invaganata, 8, Pterospermella A. It has very low Acritarch b, Pyxidinopsis. contains Tasmanites Brigantedinium pynei, it higher abundances Lejeunecysta 1 Sigmopollis than cycle. environmental interpretations CRP core workers using sedimentological paleontological indicators used to infer conditions likely have influenced assemblages. Paleontological analysis suggests deposited in cold conditions, sea ice melt water influence, although inferred existed colder more prolonged cover less associated fresh input times. application modern analogues for some taxa identified suggest presence ice, occasionally lowered salinity cycles. This consistent findings paleoenvironmental studies on cores.