International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

ORIGIN OF RHYTHMICALLY BEDDED CENOMANIAN CARBONATE ROCKS OF THE BAKHCHISARAI REGION (SW CRIMEA)

Pages: 49 - 61

Authors: RUSLAN GABDULLIN, ANDREY GUZHIKOV, IVAN DUNDIN

Abstract: Rhythmically bedded marls and limestones were studied in the Cenomanian deposits of SW part of Mountain Crimea in Ukraine. Carbonate content, TOC, XRD, foraminiferal, petromagnetic analyses and ichnofossil distribution analysis were carried out on 115 samples from 6 sections to define the nature of 5 types of rhythmicity. Marl-sandy marl rhythms of the Lower Cenomanian transform into limestone-marl rhythms of the Middle Cenomanian. Upper Cenomanian rocks contain limestone-limestone, limestone-marl rhythms and rhythmically bedded black shales (analog of „Bonarelli level“). The types of the rhythms can be classified due to lithology and their paleogeographic position. Cycles of dilution, solution and bioproduction are involved, 11 paleogeographic models are discussed, 6 are proposed. The nature of the rhythms can be connected with Milankovich cycles.

Keywords: Crimea, Cenomanian, rhythmicity, carbonate rocks, paleogeographic models

Download PDF document Show Text Version