DISTRIBUTION AND PHASE ASSOCIATION OF SOME MAJOR AND TRACE-ELEMENTS IN THE ARABIAN GULF SEDIMENTS

Twenty-four sediment samples were collected from the Arabian Gulf (ROP ME Sea) and analysed for their grain size distribution and carbonate c ontents as well as the major elements Ca, Mg, Fe and Al and macro and trace elements Mn, Sr, Ba, Zn, Cu, Cr, V, Ni and Hg. Concentration of trace elements are found comparable to previous data published for sam ples taken before and after the Gulf War, and reflect the natural back ground level. Grain size analyses, aluminium and carbonate measurement s support the presence of two major sediment types: (1) a terrigenous, fine-,grained and Al rich type predominating along the Iranian side; and (2) a coarse-grained and carbonate rich type predominating along t he Arabian side of the Gulf. Investigation of the correlation of the e lements analysed with the sediment type indicates that they could be g rouped under two distinct associations: (1) carbonate association incl uding Ca and Sr; and (2) terrigenous association comprising Al, Fe,Mg, Ba, Mn, Zn, Cu, Cr, V, Ni and Hg. Element/Al ratios calculated for th e mud non-carbonate fraction indicate that the Euphrates and Tigris ri vers have minor importance as sediment sources to the Gulf. Most of th e elements have exceptionally high aluminium ratios in sediments conta ining more than 85-90% carbonate. These sediments are restricted to th e southern and south-eastern part of the area where depth is shallow a nd temperature and salinity are high. Both biological accumulation and chemical and biochemical coprecipitation could be responsible for thi s anomaly. (C) 1998 Academic Press Limited.