The variation of cesium and 37 other elements in the Sardinian granite batholith,and the significance of cesium for granite petrogenesis

A suite of granites from the Hercynian batholith of Sardinia (Italy) was analysed for cesium and 37 other major and trace elements.Factor analysis was used to identify inter-element associations in this set of data. Cesium is shown to be closely associated with tin, lithium and rubidium, and less closely with beryllium and thallium, but it shows no correlation with any of the major elements. The role of crystal fractionation, magma mixing, and the process of partial melting in the magmatic source region are examined as possible controls of Cs distribution. The pattern of element associations revealed by factor analysis eliminates crystal fractionation and magma mixing as the main cause of magmatic variation. The variation in Cs is considered to be primary in origin, i.e. it originated in the magmatic source region. The relationship between Cs and other elements was mainly determined by the relative proportions of mica and feldspar entering the melt during anatexis.