Holocene variations in mineral and grain-size composition along the East Greenland glaciated margin (ca 67°–70°N): Local versus long-distance sediment transport

摘要: Quantitative X-Ray Diffraction (qXRD) analysis of the <2 mm sediment fraction from surface (sea floor) samples, and marine cores that span last 10–12 cal ka BP, are used to describe spatial temporal variations in non-clay mineral compositions for an area between Kangerlussuaq Trough Scoresby Sund (∼67°–70°N), East Greenland. Bedrock consists primarily early Tertiary alkaline complex with high weight% pyroxene plagioclase. Farther inland north, bedrock is dominantly felsic a quartz potassium feldspars. Principal Component (PC) indicates importance as compositional end members, abrupt shift k-feldspar dominated sediments north rich plagioclase feldspars offshore basaltic outcrop. Coarse (<2 mm or <1 mm) ice-rafted largely absent trough ∼8 5 cal ka BP, but then increase 4 cal ka BP. Compositional unmixing Grivel Basin indicate dominance local over long distance sources, pulses tidewater glaciers Nansen fjords reaching inner shelf during Neoglaciation. The change IRD more dramatic grain-size proxies than wt%. Forty seventy percent variance records either side Denmark Strait explained by low frequency trends, data Basin, Greenland, distinctly different, approximate 2500 yr periodicity.