TY - JOUR
T1 - Quartz content and the quartz-to-plagioclase ratio determined by X-ray diffraction: a proxy for ice rafting in the northern North Atlantic?
AU - Moros, M.
AU - McManus, J.F.
AU - Rasmussen, T.
AU - Kuijpers, A.
AU - Dokken, T.
AU - Snowball, I.
AU - Nielsen, T.
AU - Jansen, E.
N1 - Funding Information:
Pierre Biscaye, Mary Elliot, Simon Robinson and an anonymous reviewer are thanked for their very helpful comments. We thank Franz Gingele for many fruitful discussions. We are grateful to Christian Blauscha, Bianka Rasch and Claas Melliss for help during the sample preparation. This study was supported and funded (M. Moros) partly by the German Deutsche Forschungsgemeinschaft (GI324) and partly by an EU Marie-Curie fellowship (HPMF-CT-2002-01631). [BARD]
PY - 2004/2/15
Y1 - 2004/2/15
N2 - Many paleoceanographic reconstructions of the glacial North Atlantic include estimates of iceberg discharge, which are based on the variable abundance of ice-rafted detritus (IRD) in deep-sea sediments. IRD abundance is most often determined by the mechanical separation and painstaking counting of terrigenous particles larger than a specified threshold grain size, typically 150 μm. Here we present a new proxy for IRD based on X-ray diffraction (XRD) analysis of bulk sediments. This approach complements results obtained from standard techniques while offering several distinct advantages. In addition to the rapid production of objective data, XRD measurements on bulk sediments are sensitive to a broader and more characteristic grain size range than counts of individual coarse lithic fragments. The technique is demonstrated in a study of 12 sediment cores from the North Atlantic. Bulk quartz content and the quartz-to-plagioclase ratio exhibit peak-to-peak correspondence to manual counting results, which verifies the identification of large IRD influxes. The XRD data also reveal variations between the manually identified peaks, suggesting increased sensitivity to low-level, distal, or sea-ice sources of IRD. A saw-tooth pattern emerges in many IRD events, which supports a link between ice rafting and atmospheric temperature changes over Greenland, and providing further evidence of the influence of climate on iceberg discharges.
AB - Many paleoceanographic reconstructions of the glacial North Atlantic include estimates of iceberg discharge, which are based on the variable abundance of ice-rafted detritus (IRD) in deep-sea sediments. IRD abundance is most often determined by the mechanical separation and painstaking counting of terrigenous particles larger than a specified threshold grain size, typically 150 μm. Here we present a new proxy for IRD based on X-ray diffraction (XRD) analysis of bulk sediments. This approach complements results obtained from standard techniques while offering several distinct advantages. In addition to the rapid production of objective data, XRD measurements on bulk sediments are sensitive to a broader and more characteristic grain size range than counts of individual coarse lithic fragments. The technique is demonstrated in a study of 12 sediment cores from the North Atlantic. Bulk quartz content and the quartz-to-plagioclase ratio exhibit peak-to-peak correspondence to manual counting results, which verifies the identification of large IRD influxes. The XRD data also reveal variations between the manually identified peaks, suggesting increased sensitivity to low-level, distal, or sea-ice sources of IRD. A saw-tooth pattern emerges in many IRD events, which supports a link between ice rafting and atmospheric temperature changes over Greenland, and providing further evidence of the influence of climate on iceberg discharges.
KW - Ice rafting
KW - North Atlantic
KW - Plagioclase
KW - Quartz
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=1142281155&partnerID=8YFLogxK
U2 - 10.1016/S0012-821X(03)00675-7
DO - 10.1016/S0012-821X(03)00675-7
M3 - Article
SN - 0012-821X
VL - 218
SP - 389
EP - 401
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 3-4
ER -