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Using the tephra record to refine the dating of a West Antarctic ice core

Sinéad Flanigan1 , Joe McConnell2, Nathan Chellman2, Robert Mulvaney3, Gill Plunkett1

  • Affiliations:  1 Archaeology and Palaeoecology, School of Natural and Built Environment Queen's University Belfast, Belfast, UK; 2 Desert Research Institute, Reno, Nevada, USA;3British Antarctic Survey, Natural Environment Research Council, Cambridge, UK 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 142

  • Programme No: 3.13.11

  • Theme 3 > Session 13

Abstract

Ice cores provide globally significant paleoenvironmental records which have numerous applications. Of particular interest are their highly resolved archive of short-term environmental events. The construction of reliable and accurate chronologies is often complicated by ice-flow and compression which can result in large uncertainties in the timing of events. Volcanic signals are an established method of creating tie-points between ice cores, enabling chronological control from robustly dated cores to be transferred to less well constrained records. Volcanic events can be deduced from spikes in the sulphur record but lag times between an event and deposition in the ice and long-lasting signals can result in less accurate tie-points. To combat this, tephra deposits can be investigated to provide age-equivalent and independently dated linkages between cores. Here we present the preliminary results of a tephrochronological investigation of the Fletcher Ice Core (FIC) drilled from West Antarctica by the British Antarctic Survey. Initial analysis suggests the 654 m-long core extends back to 130 ka, with confident dating of the last 3500 years through cross-dating the chemical record with the WAIS Divide core. Guided by previous tephra research in Antarctica, we target specific volcanic events known to have deposited tephra in Antarctica with the aims of i) corroborating the age model of the Late Holocene section of the FIC core and, ii) establishing fixed tie-points for the Late Glacial ice. We outline our results and discuss the significance of our findings for the Antarctic tephrochronological record and applications thereof.