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Geochemical discrimination of Early Palaeogene bauxites in Croatia

Two discriminant function models were created in order to distinguish between major- and trace- element geochemical patterns typical of Lower Palaeogene (Paleocene, Pc) bauxites formed on the portion of the carbonate platform comprising the Karst or External Dinarides. Four groups of bauxites from Istria, North Adriatic Islands, North Dalmatia and Central Dalmatia have been neatly separated into their characteristic compartments according to specific combinations of major and trace elements expounding characteristic conditions and processes prevailing in the karst environment during subaerial exposure of the carbonate platform. Typically, in both models the first discriminant function explains the most part of the system variability. However, the trace- element model proves itself as a more helpful predictive tool representing the straightforward example of absolutely correct classification of samples into four pre-defined groups of Pc bauxites. Generally, both models follow a characteristic trend in geochemical signature related to recent geographical position of the bauxite deposits – decrease of K2O and increase of the Cr content following the SE direction (from Istria to Dalmatia) – which is most probably caused by predominant environmental conditions during the AdCP Cretaceous-Palaeogene emergent stage (Istria), and emplacement of parent rocks (ophiolite belt) supplying the necessary material for bauxite genesis (Central Dalmatia), respectively.

Bauxite ; Adriatic Carbonate platform ; Dinarides ; Geochemistry ; Discriminant function model

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