Recycled Pliocene foraminifera from the CRP-1 Quaternary succession

Mixed assemblages of Pliocene and Quaternary foraminifera occur within the Quaternary succession of the CRP-1 drillhole.Pliocene foraminitcra arc not present in the lowermost Unit4.1.are rare in Unit 3.1 and 2.3, arc relatively common in Units 2.2 and 2.1, and arc absent in Unit 1.1.Fifteen and twelve species were documented in two of the samples from Units 2.2 and 2.1 respectively.A census count of foi'aminifera in a sample at 26.89 mbsf (Unit 2.2) indicated that 39% of the tests were from a Pliocene source.with the remaining 61 % tests assigned to the in situ Quaternary assemblage.Tlicrc appears to be a close correlation between the stratigraphic distribution of ice-rafted sediments and the test number and diversity of Pliocene taxa.It is concluded that Pliocene assemblages were not derived from submarine outcrops on Roberts Ridge, but are more likely to have been raftcd to the site via major trunk valley drainage systems such as operated within the Mackay and Ferrar glacial valleys.The CO-occurrence of marine biota (including foraminifera).fossil wood, pollen.and igneous clasts in the Quaternary succession of CRP-l.points to the marine and terrestrial facies of the Pliocene Sirius Group as a likely source.A major episode of erosion and transport of sediment into the offshore marine basins at about -1 Ma may have been triggered by dynamism in the ice sheet-glacier system.an episode of regional uplift in the Transantarctic Mountains, sea level oscillations and associated changes in the land-to-sea drainage baselines, or some combination of these factors.