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Tracking the provenance of Greenland-sourced, Holocene aged, individual sand-sized ice-rafted debris using the Pb-isotope compositions of feldspars and 40Ar/39Ar ages of hornblendes

Tracking the provenance of Greenland-sourced, Holocene aged, individual sand-sized ice-rafted debris using the Pb-isotope compositions of feldspars and 40Ar/39Ar ages of hornblendes
Tracking the provenance of Greenland-sourced, Holocene aged, individual sand-sized ice-rafted debris using the Pb-isotope compositions of feldspars and 40Ar/39Ar ages of hornblendes
The provenance of sand-sized ice-rafted debris (IRD) sourced from Greenland is currently difficult to determine. Such knowledge, if it could be ascertained with a high degree of certainty, could be applied to the Greenland-proximal marine records to improve both our understanding of modern-day spatial patterns of iceberg rafting and the past history of the Greenland Ice Sheet (GIS). Recent studies have highlighted the utility of the Pb-isotope composition of individual sand-sized feldspars and the 40Ar/39Ar ages of individual sand-sized hornblendes in this regard. However, before any such provenance toolkit can be applied to the palaeo-record, it is necessary first to determine whether this approach can be used to track the sources of known recent Greenland-proximal IRD deposition. To this end we present new records of the Pb-isotope composition and the 40Ar/39Ar ages of individual sand-sized grains of feldspars and hornblendes, respectively, from modern Greenland glacifluvial and fjord sands and Holocene to modern Greenland-proximal marine sediments. These new data demonstrate that sand-sized feldspars and hornblendes glacially eroded by the GIS exhibit distinct intra- and inter-tectonic terrane differences in their Pb-isotope compositions and ages and that these differences are clearly expressed in the geochemistry and geochronology of sand-sized IRD deposited in marine sediments around Greenland. Although overlap exists between some Greenland-proximal IRD ‘source fields’ defined by these data, our approach has the potential to both better understand spatial patterns of Greenland-derived IRD in the modern day as well as during past episodes of iceberg calving.
Greenland, ice rafted debris, Ar–Ar, Pb isotopes, icebergs, provenance
0012-821X
192-203
White, Lee F.
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Bailey, Ian
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Foster, Gavin L.
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Allen, Georgina
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Kelley, Simon P.
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Andrews, John T.
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Hogan, Kelly
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Dowdeswell, Julian A.
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Storey, Craig D.
df3c8e4d-58e4-4df8-9a4e-9533ae534b4d
White, Lee F.
cd13f54f-5cda-4f7f-b99c-fdf740c36b42
Bailey, Ian
e659068f-e591-4185-afd1-5e19a5794bda
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Allen, Georgina
d92a9004-37e1-4c2f-878b-4bcd9eb7b447
Kelley, Simon P.
09eeeb7b-c0a5-43ce-86e0-9e692f156876
Andrews, John T.
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Hogan, Kelly
a9604862-d9fc-4944-aca2-074492ae58cd
Dowdeswell, Julian A.
106dce8d-e831-4407-b65d-575452be2cb8
Storey, Craig D.
df3c8e4d-58e4-4df8-9a4e-9533ae534b4d

White, Lee F., Bailey, Ian, Foster, Gavin L., Allen, Georgina, Kelley, Simon P., Andrews, John T., Hogan, Kelly, Dowdeswell, Julian A. and Storey, Craig D. (2016) Tracking the provenance of Greenland-sourced, Holocene aged, individual sand-sized ice-rafted debris using the Pb-isotope compositions of feldspars and 40Ar/39Ar ages of hornblendes. Earth and Planetary Science Letters, 433, 192-203. (doi:10.1016/j.epsl.2015.10.054).

Record type: Article

Abstract

The provenance of sand-sized ice-rafted debris (IRD) sourced from Greenland is currently difficult to determine. Such knowledge, if it could be ascertained with a high degree of certainty, could be applied to the Greenland-proximal marine records to improve both our understanding of modern-day spatial patterns of iceberg rafting and the past history of the Greenland Ice Sheet (GIS). Recent studies have highlighted the utility of the Pb-isotope composition of individual sand-sized feldspars and the 40Ar/39Ar ages of individual sand-sized hornblendes in this regard. However, before any such provenance toolkit can be applied to the palaeo-record, it is necessary first to determine whether this approach can be used to track the sources of known recent Greenland-proximal IRD deposition. To this end we present new records of the Pb-isotope composition and the 40Ar/39Ar ages of individual sand-sized grains of feldspars and hornblendes, respectively, from modern Greenland glacifluvial and fjord sands and Holocene to modern Greenland-proximal marine sediments. These new data demonstrate that sand-sized feldspars and hornblendes glacially eroded by the GIS exhibit distinct intra- and inter-tectonic terrane differences in their Pb-isotope compositions and ages and that these differences are clearly expressed in the geochemistry and geochronology of sand-sized IRD deposited in marine sediments around Greenland. Although overlap exists between some Greenland-proximal IRD ‘source fields’ defined by these data, our approach has the potential to both better understand spatial patterns of Greenland-derived IRD in the modern day as well as during past episodes of iceberg calving.

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Published date: January 2016
Keywords: Greenland, ice rafted debris, Ar–Ar, Pb isotopes, icebergs, provenance
Organisations: Geochemistry

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Local EPrints ID: 385545
URI: https://eprints.soton.ac.uk/id/eprint/385545
ISSN: 0012-821X
PURE UUID: 57b14f40-574e-4444-ab41-5e20a2fe1fdd
ORCID for Gavin L. Foster: ORCID iD orcid.org/0000-0003-3688-9668

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Date deposited: 06 Jan 2016 11:36
Last modified: 15 Aug 2019 00:39

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Contributors

Author: Lee F. White
Author: Ian Bailey
Author: Gavin L. Foster ORCID iD
Author: Georgina Allen
Author: Simon P. Kelley
Author: John T. Andrews
Author: Kelly Hogan
Author: Julian A. Dowdeswell
Author: Craig D. Storey

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