Diagenesis of sediments beneath the Ross Ice Shelf and their sedimentary history

Abstract

Micropalaeontological studies of sediment cores collected from beneath the Ross Ice Shelf, Antarctica, give conflicting stratigraphical interpretations. The diatom flora initially indicated an in situ succession of later middle Miocene age^1,2, which was supported by the occurrence of benthic foraminifera³. However, subsequent diatom analyses record the presence of flora with mixed ages (mostly Miocene but also Pliocene and Pleistocene) throughout both of the two lithological units present in the cores. These flora are taken to indicate repeated reworking, which most recently occurred no earlier than the late Pleistocene⁴. These contrasting views have since been re-affirmed^5,6. Our studies of sediment geochemistry show self-consistent patterns in organic carbon, organic nitrogen and sulphur diagenesis which suggest a Recent, in situ origin, at least for the upper unit.