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The Upper Cretaceous-Paleogene Carbonate Sediments in Well Istra More-5 (northern Adriatic, Croatia)

The wildcat well Istra More-5 is located in the northern Adriatic, northwest of Pula. Lower Eocene and Paleocene deep-marine sediments have been bored in the interval 1725-1770 m. Drilling was stopped at depth of 1880 m in the Maastrichtian deep-marine pelagic micrites and bioclastic fine-grained calcarenites. Pelagic micrites contain variable amount of fragment of rudists, echinoderms, large benthic and numerous planktonic forams and bioclastic fine-grained calcarenites mostly fragments of rudists, benthic forams, ehinoderms, corallina algae. The Maastrichtian limestones were deposited in region distal to source of the material, i. e. lower slope - basin. The Paleocene - Lower Eocene are composed of clayey limestone (micrite with numerous small planctonic foraminifers) with laminae and intercalatins of allochthonous bioclastic limestones formed by turbidite flows on the distally area of lower slope or in the basin plain. SEM analyses show that laminae of clay are illite-chlorite association with includes accumulations of cryptocrystalline dolomite, calcite, neutral plagioclase, flaky chlorite, muscovite and sporadically nannoplanctons.

Deep-marine sediments; Paleocene-Lower Eocene; Maastrichtian; Large benthic foraminifers; Northern Adriatic

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