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

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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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 : , Open Access version :