期刊
JOURNAL OF QUATERNARY SCIENCE
卷 24, 期 7, 页码 664-676出版社
WILEY-BLACKWELL
DOI: 10.1002/jqs.1257
关键词
Iceland; Holocene; ice-rafted debris (IRD); X-ray diffraction; marine sediments; quartz
资金
- NSF [ATM-052515]
- [ATM-9531397]
- [OCE-9809001]
Quantitative X-ray diffraction analysis of the <2 mm sediment fraction was carried out on 1257 samples (from the seafloor and 16 cores)from the Iceland shelf west of 18 degrees 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 a 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 cm(-2) a(-1)) at MD99-2269 off N Iceland. The multi-taper method indicated that there are three significant frequencies at the 95% confidence level with periods of ca. 2500, 445 and 304 a. Regime shift analysis pinpoints intervals when there was a statistically significant shift 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 delta O-18 data on planktonic foraminifera) and intervals of moraine building. Copyright (C) 2009 John Wiley & Sons, Ltd.
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