Sub-ice Shelf Sediment Geochronology Utilizing Novel Radiocarbon Methodology for Highly Detrital Sediments

Authors

C. Subt, University of South FloridaFollow
H. I. Yoon, Korea Polar Research Institute
K. C. Yoo, Korea Polar Research Institute
J. I. Lee, Korea Polar Research Institute
A. Leventer, Colgate University
Eugene W. Domack, University of South Florida
Brad E. Rosenheim, University of South FloridaFollow

Document Type

Article

Publication Date

2017

Keywords

Antarctica, radiocarbon, sediment chronology, Ramped PyrOx

Digital Object Identifier (DOI)

https://doi.org/10.1002/2016GC006578

Abstract

Sub-ice shelf sediments near Larsen C ice shelf (LIS-C) show fine-scale rhythmic laminations that could provide a near-continuous seasonal-resolution record of regional ice mass changes. Despite the great potential of these sediments, a dependable Late Quaternary chronology is difficult to generate, rendering the record incomplete. As with many marginal Antarctic sediments, in the absence of preserved carbonate microfossils, the reliability of radiocarbon chronologies depends on presence of high proportions of autochthonous organic carbon with minimized detrital organic carbon. Consequently, acid insoluble organic (AIO) ¹⁴C dating works best where high productivity drives high sediment accumulation rates, but can be problematic in condensed sequences with high proportions of detrital organic carbon. Ramped PyrOx ¹⁴C dating has progressively been shown to improve upon AIO ¹⁴C dates, to the point of matching foraminiferal carbonate ¹⁴C dates, through differential thermochemical degradation of organic components within samples. But in highly detrital sediments, proportions of contemporaneously deposited material are too low to fully separate autochthonous organic carbon from detrital carbon in samples large enough to ¹⁴C date. We introduce two modifications of the Ramped PyrOx ¹⁴C approach applied to highly detrital sediments near LIS-C to maximize accuracy by utilizing ultra-small fractions of the highly detrital AIO material. With minimization of the uncertainty cost, these techniques allow us to generate chronologies for cores that would otherwise go undated, pushing the limits of radiocarbon dating to regions and facies with high proportions of pre-aged detritus. Wider use of these techniques will enable more coordinated a priori coring efforts to constrain regional glacial responses to rapid warming where sediments had previously been thought too difficult to date.

Rights Information

Terms of use for work posted in Scholar Commons.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Geochemistry, Geophysics, Geosystems, v. 18, issue 4, p. 1404-1418

©2017. American Geophysical Union. All Rights Reserved.

Scholar Commons Citation

Subt, C.; Yoon, H. I.; Yoo, K. C.; Lee, J. I.; Leventer, A.; Domack, Eugene W.; and Rosenheim, Brad E., "Sub-ice Shelf Sediment Geochronology Utilizing Novel Radiocarbon Methodology for Highly Detrital Sediments" (2017). Marine Science Faculty Publications. 2430.
https://digitalcommons.usf.edu/msc_facpub/2430