10.1594/PANGAEA.802673Krissek, Lawrence ALawrence AKrissek0009-0002-1596-0699Morley, Joseph JJoseph JMorleyLofland, Darlene KDarlene KLoflandPANGAEA1985Event labelSample code/labelDEPTH, sediment/rockAGESize fraction 2.000-0.250 mmIce rafted debrisVolcanic componentsBiogenic particlesDrilling/drill rigDSDP/ODP/IODP sample designationWet sievingCounting 250-2000 µm fractionLeg86Glomar ChallengerDeep Sea Drilling Project (DSDP)1982-06-01T00:00:00/1982-06-06T00:00:00Supplementary Dataset10.2973/dsdp.proc.86.128.19851227 data pointstext/tab-separated-valuesCreative Commons Attribution 3.0 UnportedThe abundance and composition of the coarse-sand fraction (250 µm-2 mm) of samples from Deep Sea Drilling Project Sites 579 and 580 were investigated to determine the chronology of ice rafting at these locations.
The ice-rafting signal at these sites is reduced relative to the generalized ice-rafting chronology of the North Pacific (Kent et al., 1971) because of increased distance to the ice-rafting source areas. These data, however, do record the general increase in ice-rafting importance as sediment age decreases, especially between 0 and 1.0 m.y. ago. In addition, peaks in ice-rafting importance since 1.0 m.y. ago at Sites 579 and 580 are generally synchronous with periods of major ice-rafting influence throughout the North Pacific. The first occurrence of ice-rafted debris at the Matuyama/Gauss magnetic boundary supports a proposed age of approximately 2.47 m.y. for the onset of major Northern Hemisphere glaciation.
The coarse-sand fraction at Sites 579 and 580 contains a significant component of non-ice-rafted material, particularly biogenic particles and volcanic pumice. Under these conditions, the standard assumption that the weight percent of the coarse-sand fraction reflects variations in ice-rafting importance may not be valid. For samples taken at some distance from the source of ice-rafted debris, both the abundance and the composition of the coarse-sand fraction must be considered to obtain a valid measure of the influence of sediment transport via ice rafting.Supplement to: Krissek, Lawrence A; Morley, Joseph J; Lofland, Darlene K (1985): The occurrence, abundance, and composition of ice-rafted debris in sediments from Deep Sea Drilling Project Sites 579 and 580, Northwest Pacific. In: Heath GR; Burckle LH; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 86, 647-655153.8362153.976338.626841.6245North Pacific Ocean