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Mineralogy and isotope chemistry of GISP2 and potential source areas

Authors
Publisher
PANGAEA
Publication Date
Identifiers
DOI: 10.1594/pangaea.730452
Keywords
  • 143Nd/144Nd
  • 206Pb/204Pb
  • 206Pb/207Pb
  • 207Pb/204Pb
  • 208Pb/204Pb
  • 208Pb/206Pb
  • 87Sr/86Sr
  • Als
  • Als Flux
  • Alsi Are Aluminosilicate Insoluble Particles
  • Aluminosilicate Insoluble Particles
  • Aluminosilicate Insoluble Particles Flux
  • Ca2+
  • Calcium
  • Chl
  • Chlorite
  • Comment
  • Crystal Size
  • Depth
  • Bottom/Max
  • Depth
  • Top/Min
  • Depth Bot
  • Depth Top
  • Drilling
  • Fairbanks
  • Gisp
  • Gisp2
  • Gisprefsamp245-5
  • Gisprefsamp245-6
  • Gisprefsamp248-1
  • Gisprefsamp248-2
  • Gisprefsamp248-3
  • Gisprefsamp248-4
  • Gisprefsamp248-5
  • Gisprefsamp248-6
  • Gisprefsamp248-7
  • Gisprefsamp248-8
  • Gisprefsamp251-3
  • Gisprefsamp251-4
  • Gisprefsamp251-5
  • Gisprefsamp251-6
  • Gobi Desert
  • Greenland Ice Core Projects
  • Grip/Gisp/Ngrip
  • Ill
  • Illinois
  • United States Of America
  • Illite
  • Kaolinite
  • Kln
  • Lead 206/Lead 204 Ratio
  • Lead 206/Lead 207
  • Lead 207/Lead 204 Ratio
  • Lead 208/Lead 204 Ratio
  • Lead 208/Lead 206 Ratio
  • Neodymium 143/Neodymium 144
  • Sampling/Drilling Ice
  • Sampling By Hand
  • Shaanxi
  • Size
  • Sme
  • Smectite
  • Strontium 87/Strontium 86
  • Toronto
  • Ukraine
  • Washington
  • X-Ray Diffraction Textur
  • Clay Fraction
Disciplines
  • Earth Science

Abstract

Samples of dust from the Greenland Ice Sheet Project 2 (GISP2) ice core, Summit, Greenland, dated within marine isotope stage 2 (between 23,340 and 26,180 calendar years B.P.) around the time of the coldest, local, last glacial temperatures, have been analyzed to determine their provenance. To accomplish this, we have compared them with approximately Coeval aeolian sediments (mostly loesses) sampled in possible source areas (PSAs) from around the northern hemisphere. The <5-µm grain-size fraction of these samples was analyzed on the basis that it corresponds to the atmospheric dust component of that time and locale, which was sufficiently fine grained to be transported over long distances. On the basis of comparison of the clay mineralogy and Sr, Nd and Pb isotope composition with ice dust and PSAs and assuming that we have sampled the most important PSAs, we have determined that the probable source area of these GISP2 dusts was in eastern Asia. The dust was not derived from either the midcontinental United States or the Sahara, two more proximal areas that have been suggested as potential sources based on atmospheric circulation modeling. Except for a brief period during an interstadial, when dust transport was exceptionally low (for glacial times) and had a mineralogical composition indicative of a slightly more southern provenance, the source area of the dust did not change significantly during times of variably higher fluxes of dust with larger mean grain size or lower fluxes of dust with smaller mean grain size. This includes the high-dust period that correlates with the Heinrich 2 period of major iceberg discharge into the North Atlantic. Variable wind strengths must therefore be invoked to account for these abrupt and significant changes in dust flux and grain size.

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