Coarse-fraction sediment (>63 µm) studies for Leg 151 Sites 908 and 909 have enabled us to reconstruct the paleoclimate since the early Miocene (18.0 Ma) of the Fram Strait, in order to better understand this gateway between the North Atlantic and the Arctic Ocean. Study of the grain-size distribution patterns (subfractions 63-125 µm, 125-250 µm, 500-1000 µm, and >1000 µm plus the coarse-component composition) suggests possible seasonal ice-rafting starting as early as 14.0 Ma. Also shown is a clear signal of ice-rafting events between 10.8 and 8.6 Ma, 7.2 and 6.8 Ma, 6.3 and 5.5 Ma, and since 5.0 Ma. Evidence indicates that the initiation of the East Greenland Current took place at 10.8 Ma and is related to the reorganization and shutdown of deep-water connections in the Middle and Central American Seaways during the latest middle to late Miocene. During Pliocene-Pleistocene, the polar front moved over Site 908, covering the area with sea ice and pack ice during the Pleistocene (between 1.9 and 1.2 Ma). The West Spitsbergen Current episodically reached the Fram Strait during the Pliocene-Pleistocene, suggesting that the Norwegian Sea was never completely covered by sea ice and pack ice in that era.
Date of initial receipt: 14 July 1995
Date of acceptance: 11 December 1995
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