Flux of ice-rafted detritus from sea ice in the Fram Strait

A three-year particle flux record from the eastern Fram Strait, between Gre enland and Svalbard, revealed a rather untypical seasonal flux pattern comp ared to other particle flux studies from the Nordic Seas. In the eastern Fr am Strait this pattern is characterised by a sudden four- to six-fold incre ase of the particle flux in January, when no daylight is available to suppo rt any biological productivity. Comparison with sea-ice distribution maps l ed to the conclusion that the sudden increase in the flux is due to ice-raf ted detritus released from sea ice, which originated from the Svalbard arch ipelago and from the northern Barents Sea. Detailed grain size analyses of the silt fraction indicated the > 10 mu m fraction of the lithogenic matter to be clearly enriched due to IRD input. Even more important is the observ ation that lithogenic material > 40 mu m occurs exclusively during the ice- rafting event and, therefore, appears to be a suitable indicator for IRD tr ansported on sea ice. Thus, in addition to coarse IRD (e.g. > 500 mu m), wh ich is mainly derived from icebergs, the analysis of fine IRD (> 40 mu m) i n deep-sea sediments can be used to reconstruct paleo-sea-ice extensions. ( C) 2000 Elsevier Science Ltd. All rights reserved.