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

Type Article
Date 2016-01
Language English
Author(s) White Lee F.1, Bailey IanORCID2, Foster Gavin L.2, Allen Georgina2, Kelley Simon P.3, Andrews John T.4, 5, Hogan Kelly6, Dowdeswell Julian A.6, Storey Craig D.1
Affiliation(s) 1 : Univ Portsmouth, Sch Earth & Environm Sci, Portsmouth PO1 3QL, Hants, England.
2 : Univ Southampton, Natl Oceanog Ctr Southampton, Ocean & Earth Sci, Southampton SO14 3ZH, Hants, England.
3 : Open Univ, Dept Environm Earth & Ecosyst, Milton Keynes MK7 6AA, Bucks, England.
4 : Univ Colorado, INSTAAR, Boulder, CO 80309 USA.
5 : Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA.
6 : Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England.
Source Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2016-01 , Vol. 433 , P. 192-203
DOI 10.1016/j.epsl.2015.10.054
WOS© Times Cited 18
Keyword(s) Greenland, ice rafted debris, Ar-Ar, Pb isotopes, icebergs, provenance
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 Ar-40/Ar-39 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 Ar-40/Ar-39 ages of individual sand-sized grains of feldspars and homblendes, respectively, from modern Greenland glacifluvial and ford 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.

Full Text
File Pages Size Access
Publisher's official version 12 2 MB Open access
MMC 1. This document contains text that details the specifics of our laser ablation MC-ICP-MS method and construction of the Gaussian curves used to present our Ar–Ar geochronological data 4 317 KB Open access
MMC 2 All raw data is presented in Tables S1, S2 and S3, which detail the Pb–Pb isotope ratios of Greenland sources (S1) and marine sinks (S2), in... 75 KB Open access
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How to cite 

White Lee F., Bailey Ian, Foster Gavin L., Allen Georgina, Kelley Simon P., Andrews John T., Hogan Kelly, Dowdeswell Julian A., 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. Publisher's official version : https://doi.org/10.1016/j.epsl.2015.10.054 , Open Access version : https://archimer.ifremer.fr/doc/00421/53292/