Glacial-interglacial relationship between carbonate components and sediment reflectance in the North Atlantic

A high-resolution composite sediment record from intermediate water depths in the North Atlantic, dating back to marine isotope stage (MIS) 13, was in vestigated in order to determine the relationship between sediment reflecta nce (gray level%) and carbonate content (weight%). For this purpose, a deta iled analysis of the coarse ( > 20 mum) and fine ( < 20 mum) carbonate comp onents was carried out to assess which of the two carbonate components driv es glacial-interglacial changes in sediment gray level. The results indicat e that the bulk carbonate component is clearly dominated by the fine carbon ate fraction, regardless of glacial or interglacial climatic mode, suggesti ng that the sediment gray level is usually controlled by fluctuations of th e fine carbonate content. However, a comparison of MIS 1 and 5.5 indicates that, besides this difference in the contents of the two carbonate size fra ctions, changing modes in carbonate preservation, i.e., the preservational state of planktonic Foraminifera, may also have a profound influence on tot al sediment reflectance.