Iceland Shelf 12KYr Quartz and K-Feldspar IRD Data Andrews, J.T. Andrews, J.T. sea ice earth science/paleoclimate/paleoceanography (potassium feldspar,sediment,null,weight percent,null,paleoceanography,null,x-ray diffraction,N,derived from < 2 mm sediment fraction) earth science/paleoclimate/paleoceanography (age,null,null,calendar year before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (quartz,sediment,null,weight percent,null,paleoceanography,null,x-ray diffraction,N,derived from < 2 mm sediment fraction) earth science/paleoclimate/paleoceanography (mineral index,sediment,null,weight percent,null,paleoceanography,averaged,x-ray diffraction,N,quartz and feldspar) earth science/paleoclimate/paleoceanography (mineral index,sediment,one standard deviation,weight percent,null,paleoceanography,averaged,x-ray diffraction,N,quartz and feldspar) earth science/paleoclimate/paleocean (B997-324>LATITUDE 66.52>LONGITUDE -21.15) (MD99-2263>LATITUDE 66.679>LONGITUDE -24.197) (B997-316>LATITUDE 66.746>LONGITUDE -18.79) (B997-315>LATITUDE 66.736>LONGITUDE -24.332) (B997-325 >LATITUDE 66.573>LONGITUDE -20.996) (B997-330>LATITUDE 65.87>LONGITUDE -21.08) (MD99-2266>LATITUDE 66.228>LONGITUDE -23.265) (MD99-2269>LATITUDE 66.63>LONGITUDE -23.85) (B997-321>LATITUDE 66.88>LONGITUDE -18.97) (B997-347>LATITUDE 63.21>LONGITUDE -24.17) (B997-320>LATITUDE 66.335>LONGITUDE -18.5) (MD99-2264>LATITUDE 66.679>LONGITUDE -24.197) (B997-317>LATITUDE 66.58>LONGITUDE -18.87) (B997-319>LATITUDE 66.442>LONGITUDE -18.851) Quantitative X-ray diffraction analysis of the < 2mm sediment fraction was carried out on 1257 samples (from the seafloor and 16 cores) from the Iceland shelf west of 18°W. All but one core (B997-347PC) were from transects along troughs on the NW to N-central shelf, an area that in modern and historic times has been affected by drift ice. The paper focuses on the non-clay mineralogy of the sediments (excluding calcite and volcanic glass). Quartz and potassium feldspars occupy similar positions in an R-mode Principal Component analysis, and oligoclase feldspar tracks quartz; these minerals are used as a proxy for ice-rafted detritus (IRD). Accordingly the sum of these largely foreign minerals (Q&K) (to Icelandic bedrock) is used as a proxy for drift ice. A stacked, equi-spaced 100-yr record is developed which shows both low frequency trends and higher frequency events. The detrended stacked record compares well with the flux of quartz (mg/cm2/yr) at MD99-2269 off N Iceland. The multi taper method (MTM) indicated that there are three significant frequencies at the 95% confidence level with periods of ~2500, 445, and 304 yr. Regime shift analysis pinpoints intervals when there was a statistically significant shifts in the average Q&K weight%, and identifies four IRD-rich events separated by intervals with lower inputs. There is some association between peaks of IRD input, less dense surface waters (from 18O data on planktonic foraminifera), and intervals of moraine building. STUDY NOTES: The data are derived from quantitative X-ray diffraction analysis of the < 2 mm sediments from a series of cores around Iceland, all west of 18°W. The bedrock of Iceland is essentially devoid of quartz and k-feldspars (Q and K) and these minerals are frequently used as an index for the occurrence of drift ice (sea ice or icebergs). The data for all the cores have been processed using Analyseries so that there is a wt% estimate every 100-yr between 0 and 12,000 cal yr BP. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Andrews, J.T. 2011-12-28 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/12357 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.xls English https://www.ncdc.noaa.gov/paleo/study/12357 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/andrews2009b/andrews2009b.xls Andrews, J.T. 2009. Seeking a Holocene drift ice proxy: non-clay mineral variations from the SW to N-central Iceland shelf: trends, regime shifts, and periodicities. Journal of Quaternary Science, Vol. 24, Issue 7, pp. 664-676, October 2009. DOI: 10.1002/jqs.1257 START YEAR: 12000 cal yr BP * END YEAR: 0 cal yr BP -24.332 63.21 -18.5 66.88