Micropaleontological observations on the Lower Cretaceous iron ore-related formations of the Mecsek Mts. (Upper Valanginian–Lower Hauterivian, South Hungary)

Bujtor, László and Szinger, Balázs (2018) Micropaleontological observations on the Lower Cretaceous iron ore-related formations of the Mecsek Mts. (Upper Valanginian–Lower Hauterivian, South Hungary). Central European Geology, 61 (2). pp. 136-159. ISSN 1788-2281

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Abstract

The Late Valanginian–Early Hauterivian iron ore deposit and related formations at Zengővárkony (Mecsek Mts., South Hungary) provided a relatively rich microfauna of foraminifera, crustacean microcoprolites, and sponge spicules. Benthic foraminifera are recognized in decreasing abundance: Glomospira cf. gordialis (Jones and Parker 1860), Lenticulina sp., Spirillina sp., Nodosaria sp., Epistomina sp., and Trocholina sp. A Hedbergella sp. indicates the presence of planktonic foraminifera around the ore deposit. Besides this microfauna, sponge spicules (diactine-type criccorhabds and anactine-type rhax forms) are first recorded from this environment. Rock-forming quantities of various ichnospecies of crustacean microcoprolites are recorded. Favreina hexaochetarius, Palaxius tetraochetarius, and Palaxius decaochetarius isp. provided statistically evaluated quantities in thin sections, which point to a complete crustacean ichnofauna from juveniles to adults. Four different microfossil assemblages are recognized from the Apátvarasd Limestone Fm: (a) Glomospira-dominated foraminifer assemblage, (b) diverse crustacean microcoprolite assemblage dominated by Palaxius, (c) monotypic Favreina assemblage, and (d) diverse sponge-dominated assemblage. These assemblages are similar to that of the Recent Aegean Sea hydrothermal field communities. The remains of an undetermined crinoid from dissolved rock sample may indicate a vivid sea-bottom environment.

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