Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Holocene centennial to millennial-scale deep flow strength: a case study from the Faeroe Shetland Channel

Detailed magnetic data have been obtained from core HM03-133-25 collected during a Norwegian-British cruise in the Faeroe Shetland region. The magnetic mineralogy is dominated by magnetites in the pseudosingle domain range. The size of the magnetic grains is a little larger during early Holocene than after illustrating either a slightly more active bottom current or more simply, a re-suspension of non-sorted material just after deglaciation occurred. Both long term and short term trends are observed both in the magnetic grain size and in the concentration of magnetic grains within the sediment. On the long-term, the data can be fitted by a fourth order polynomial in which more magnetic grains are synchronous with coarser grains. Both illustrate more active bottom current and this happen in the early Holocene and around 5-4 kyr B.P. When detrended, the grain size and concentration data also exhibit the same pattern with fine magnetic grains always associated with less magnetic grains (i.e. weak bottom current). Several events of weak bottom current activity are recognized and they are (within the accuracy of the preliminary age model) around 7.9; 7.5; 5.7; 4.8; 4.2; 3.6; 2.2 kyr. A spectral analysis will be conducted when the final reliable age model will be available.

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