Contribution to the Ostracode Fauna (Crustacea), Paleoecology and Stratigraphy of the Clay Pit Mataschen (Lower Pannonian, Styrian Basin, Austria)

Abstract: Sediments of the clay pit Mataschen (SE-Styria) are subdivided lithostratigraphically into approx. 1.5 m thick sandy deposits at the bottom (uppermost part of the Gleisdorf Fm.) about 5 m thick pelits with plant-remains and autochthonous tree trunks at the base (Eisengraben Mb.), around 17 m thick alternations of sandy pelits and fine sands (Sieglegg Mb.) and >3 m thick sandy beds at the top (Paldau Fm.). These units are correlated with 4th order sequences. Biostratigraphically at least the Eisengraben Mb. can be placed within the Mytilopsis ornithopsis Zone ("Zone B") of the Lower Pannonian (Upper Miocene).
The two units at the base yielded 27 ostracode taxa which are stressed for paleoecological investigations: Darwinula stevensoni, Vestalenula cylindrica, Candona (Caspiolla) cf. venusta, Candona (Lineocypris) cf. fahrioni, Candona (Lineocypris) cf. hodonensis, Candona (Typhlocyprella) sp. 1, Candona (Typhlocypris) aff. eremita, Fabaeformiscandona ex gr. balatonica, Pseudocandona sp. 1, Cypria sp. 1, Ilyocypris sp. 1, Amplocypris sp. 1, Cyprinotus sp. 1, Hungarocypris sp. 1, Callistocythere sp. 1, Euxinocythere lacunosa, Mediocytherideis sp. 1, Cyprideis macrostigma, Cyprideis cf. obesa, Hemicytheria folliculosa, Hermicytheria loerentheyi, Hemicytheria aff. ampullata, Hemicytheria sp. 1, Loxoconcha granifera, Loxoconcha kochi, Loxoconcha kolubarae, Cytherura moravica.
The ostracode fauna from the sandy sediments at the bottom and from the basal part of the pelitic unit indicates limnic environments in contrast to associations from samples above which prove mesohaline facies. Terrigenous and freshwater influx increase in the upper part of the Eisengraben Mb. and the lowermost section of the Sieglegg Mb. and lead to the progradation of deltaic sediments towards the top.
These facies changes may be linked with major fluctuations of the lake level within the Pannonian Basin.

Key Words: Lower Pannonian/Upper Miocene; Styrian Basin; Ostracoda; Systematics; Paleoecology; Stratigraphy.

Joannea Geol. Paläont. 5: 49-129 (2004)