Stratigrafické a paleoekologické vyhodnotenie asociácie dierkavcov z vrtu HC-4 (Holíč, Viedenská panva)

Abstract

HC-4 well was drilled nearby the Holíč water reservoir well in 2020 by Aqua-Geo company to build a new water reservoir. This work aims to interpret foraminifera associations from the ditch cuttings of the Neogene (Sarmatian) sediments of the Holíč and Skalica formations (Vi-enna Basin). Deposits from (130-88 m) were assigned to the Elphidium hauerinum Zone of the Holíč Fm. and (88-3 m) into the upper Sarmatian of the Porosononion granosum Zone of the Skalica Fm. based on the occurrence of benthic index fossils. The paleoenvironment changed several times during sedimentation, mainly the oxygen content in the sediment and the salinity. We identified four foraminifera associations indicating different shallow water paleoenvironments based on other oxygen content and salinity at the bottom. Dominance of the Ammnia genus (1) association typical of eutrophic environments with reduced oxygen content and normal marine salinity, (2) association with the dominance of keeled-elphidia characterizes oligotrophic well-ventilated algae or seagrass environments. The predominance of millioid foraminifera (3) is typical of a hypersaline, shallow water environment with a plant-covered bottom. The predominance of Miliammina and Trochammina (4) represents the youngest and shallowest association representing eutrophic conditions of the tidal plateau, often with low oxygen content.

Keywords

• miocene
• central paratethys
• vienna basin
• sarmatian
• foraminifera
• holíč fm.
• skalica fm.