Ohneiser C. 2023. Ross Sea PhD project proposals for chronology development and paleoenvironmental research: a report prepared for the Antarctic Science Platform. Lower Hutt (NZ): GNS Science. 15 p. (GNS Science report; 2022/51). doi:10.21420/W6HK-1424.
Abstract
A persistent issue that researchers have faced in paleoenvironmental reconstructions from Antarctic sediments is the difficulties in accurately dating cores using traditional radiocarbon (14C) methods. The inability to determine the age of sedimentary deposits greatly limits the utility of the hundreds of sediment samples collected around the Antarctic margin since the 1960s. During the Last Glacial Maximum (LGM), the Ross Embayment contained a large, grounded ice sheet that extended to the continental shelf edge. The ice retreat history and transition from a grounded ice sheet to a floating ice shelf is constrained in the western and central Ross Sea but unconstrained in the Eastern sector. Key limiting factors in better constraining the retreat history are having geographically well-positioned sediment cores and the ability to construct reliable and precise age models. This report presents paleomagnetic data from selected sediment cores in the eastern and central Ross Sea and from beneath the Ross Ice Shelf (collectively, the Ross Embayment). It outlines potential future studies aimed at developing an additional paleomagnetic geochronological tool for dating Ross Embayment sediment since the LGM ~20,000 years ago. The method is based on developing models of paleo-secular variations (PSV) of the geomagnetic field for high southern latitudes. An independently dated PSV can then provide a chronological reference for other cores where PSV can be measured. Furthermore, complimentary magnetic fabric analysis may provide a useful proxy for past ocean current velocity. Improvements in 14C dating and the development of new paleomagnetic techniques may allow for more robust dating and correlation of sedimentary cores and the reconstruction of ancient ocean current strength to provide a more reliable platform from which to reconstruct the retreat of the Ross Ice Shelf since the LGM. In this report, two PhD-level projects are proposed to (1) develop a regional Holocene geomagnetic field record and (2) derive a paleo-current meter from magnetic fabric analyses. (The authors)
