engleski

Crisis and recovery within Upper Cretaceous rudists and Middle Eocene larger foraminiferal assemblages on the Adriatic carbonate platform (Croatia).

The Adriatic carbonate platform (ACP) was a product of intense interaction between biotic and abiotic factors from the beginning in Middle Triassic till its demise in Middle/Upper Eocene. The reaction on environmental changes of the Upper Cretaceous (Turonian-Santonian) rudists and Eocene larger benhic foraminiferal assemblages from Istrian part of the platform is evaluated. On the basis of the rudist assemblages characteristics, it is visible that during Upper Cretaceousin Istrian part of the Adriatic carbonate platform, rudist react on the sea level change with different assemblages, i.e. from radiolitid communities in the shallowest part of the subtidal to the mixed radiolitid-hippuritid communities in the deeper part of the subtidal. Biofacies distribution within the Eocene sediments reveals an overall upward deepening and progressive change from oligotrophic to mesotrophic condition. It seems that orthophragminids in trying to keep pace with deepening of their habitat, became well adapted in environment with reduced light condition (within photic zone) and enhanced nutrient content.

Rudists; large benthic foraminifera; Upper Cretaceous; Middle Eocene; Adriatic carbonate platform

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