02226nas a2200241   4500000000100000000000100001008004100002653002000043653001600063653001900079653001200098653002300110100001800133700002100151700001600172700001600188245007400204856007100278300001200349490000800361520160100369020001401970       1999                            d10aHeinrich events10aice-rafting10aNorth Atlantic10aorigins10aSr and Nd isotopes1 aHilde Snoeckx1 aFrancis Grousset1 aMarie Revel1 aAn Boelaert00aEuropean contribution of ice-rafted sand to Heinrich layers H3 and H4  uhttp://www.sciencedirect.com/science/article/pii/S0025322798001686  a197-2080 v1583 aThis paper reports the Sr\textendashNd isotopic composition of the carbonate-free sand (63 μm\textendash1 mm) fraction of Heinrich layers 3 and 4 from about 17 cores from the northern Atlantic Ocean (38\textdegreeN to 68\textdegreeN). The results indicate that the transporting icebergs were calved from many ice sheets from around the North Atlantic (at least the Fennoscandian, Icelandic and Laurentide). Our isotopic data show a more distinctly European origin for ice-rafted debris (IRD) deposited during the \textquoteleftatypical Heinrich event H3 than for background IRD. In contrast, Heinrich layer H4, a representative of \textquotelefttypical Heinrich events H1, H2, H4, and H5, presents a clear dominant Laurentide signal. This result confirms that these \textquotelefttypical Heinrich events are associated with a massive discharge of icebergs from the Laurentide ice sheet. However, the theory that the Laurentide ice sheet set the events into motion [Alley, R.B., MacAyeal, D.R., 1993. Ice-rafted debris associated with binge/purge oscillations of the Laurentide Ice Sheet. Paleoceanography 9 (4), 503\textendash511] cannot explain the fact that a European signal of an early-H4 sample has been observed prior to the Laurentide signature of a late-H4 sample in the same core, along the European margin. This observation indicates that the European ice sheets may have surged before the North American ones, and suggests that the Laurentide ice sheet was not the sole motor behind the Heinrich events. Moreover, in the Norwegian Sea, IRD has a Scandinavian origin in both H3 and H4.  a0025-3227