Diatom assemblages from core sediments in the western sea area of the South Orkney Islands, Antarctica

Abstract

Holocene paleoenvironmental history in the western South Orkney Islands was reconstructedthrough the paleoecological analysis on the diatom taxa from sediment core GC02-SOI03. Thre diatom zones are identified on the basis of frequency of the critical taxa throughout the section: diatom assemblage zone I (533 cm∼360 cm), diatom assemblage zone II (352 cm∼240 cm), and diatom assemblage zone III (232 cm∼0 cm). High concentration of open water species and Eucampia antarctica var. antarctica in the diatom assemblage zone I indicates open water environment with little sea-ice during the early Holocene. Sea-ice species and Eucampia antarctica var. recta increase in abundance in the diatom assemblage zone II, suggesting increased sea-ice cover in the study area since 5 ka. Even more extensive sea-ice coverage during the late Holocene is implied by abundant sea-ice species and decreased Corethron criophilum in the diatom assemblage zone III.