Peraluminous I Type Granites

Peraluminous i type granites in the lachlan fold belt i type granites are exposed over an area 30 000 km 2 in the palaeozoic lachlan fold belt lfb and comprise almost half the total area of granites being slightly less abundant than s type granites fig.

Peraluminous i type granites.

It has previously been suggested that this may result from the fractional crystallisation of amphibole. Two mica granites are two common rock types of peraluminous granites. I type granites are rich in silica calcium and sodium but contain lesser amounts of aluminium and potassium when compared to s type granites. The peraluminous a type granites consist of four plutons namely wengshan caijiang gaoxi and fucheng for which comprehensive geochronological and geochemical data are available tables 1 and s1 in supplementary.

Many i type granites are also peraluminous despite i type source rocks typically not being saturated in al. As mentioned above herein we suggest that the high k calc alkaline peraluminous i type granites from gaoligong belt were derived from partial melting of the heterogenous source rocks in the lower crust with possible involvement. The peraluminous i type granites resulted from a low pressure partial melting process and the peraluminous a type granites were derived from a charnockite source heated by large scale magmatic. It has previously been suggested that this may result from the fractional crystallisation of amphibole.

I type peraluminous granites in the spanish central system 143 of aqueous uids e g shearer et al 1985. I type granites are typically metaluminous to weakly peraluminous. By comparing the whole rock geochemistry of typical i t ype and s type granites from lachlan fold belt lfb in southeast. Many i type granites are also peraluminous despite i type source rocks typically not being saturated in al.