Geochemistry of Istrian Lower Palaeogene bauxites — Is it relevant to the extent of subaerial exposure during Cretaceous times?

• Geochemical signatures of thefour ILPB groups is assessed using MDA of compositional data;
• Diachronism of the discontinuity surface is indicated by different geochemical signal of ILPB;
• Discriminant functions indicate geochemical processes leading to bauxite formation.

Investigation of the origin and occurrence of Istrian Lower Palaeogene bauxites discussed in this work relies on adoption of the recent perspectives on development of the collision-induced diachronous discontinuity surface in the Istrian part of the Adriatic–Dinaric carbonate platform. This process, related to the forebulge uplift at the latest stages of Alpine orogenesis, is amply recorded in the geochemical signature of contemporaneous bauxites. In order to elucidate the patterns of bauxite formation a discriminant function model based on the Compositional Data analysis (major and trace elements) is constructed providing the solid ground for separation of the bauxite groups deposited in the subaerially exposed Istrian palaeoenvironment. Complete distinction between the four a priori defined Istrian Lower Palaeogene bauxite groups achieved by the analysis demonstrates the highest degree of efficiency in characterizing environmental conditions marked by the unique suite of geochemical variables (compositions).