Marine transgression(s) to evaporite basin: The case of middle Miocene (Badenian) gypsum in the Central Paratethys, SE Poland

Danuta Peryt,Tadeusz Marek Peryt,Przemysław Gedl

doi:10.1186/s42501-020-00062-0

Abstract

The middle Miocene Badenian evaporite basin of the Carpathian Foredeep Basin was a saline lake, separated by a barrier from the sea and supplied with seawater seeping through the barrier or overflowing it occasionally in the form of short-lived marine transgressions. Such transgressions could leave behind marine microfossils in marly clay intercalations. One of them (2.3 m thick) occurs in the uppermost part of the sulphate sequence, in the unit ‘o’, in the Babczyn 2 borehole section. It contains marine palynomorphs (dinoflagellate cysts) and foraminiferal assemblages indicating a marine environment. The low-diversity benthic foraminiferal assemblages are dominated by opportunistic, shallow infaunally living species, preferring muddy or clayey substrate for thriving, brackish to normal marine salinity, and inner shelf environment. Dinoflagellate cyst assemblages, although taxonomically impoverished, consist of marine species; euryhaline forms that tolerate increased salinity are missing. Relatively common microfossils found in clay intercalations within gypsum have important palaeogeographical implications: they strongly suggest that there existed an additional inflow channel supplying the Polish Carpathian Basin from the south during the evaporite deposition and afterwards.

Highlights

The Paratethys was an epicontinental sea that developed as a relic of the Tethys
It existed between early Oligocene and late middle Miocene times and constituted a system of marine basins extending from the Alpine-Carpathian region to the modern Aral Sea during Oligocene to Miocene times
6 Discussion As the Badenian evaporite basin was located in a depression in which the brine top level occurred below the contemporaneous sea level, it could be subject to rapid flooding when the sea level rose or when the physical barrier blocking this basin from the Tethys/Paratethys reservoir was temporarily removed (Peryt 2006)

Summary

Introduction

The Paratethys was an epicontinental sea that developed as a relic of the Tethys It existed between early Oligocene and late middle Miocene times and constituted a system of marine basins extending from the Alpine-Carpathian region to the modern Aral Sea during Oligocene to Miocene times. Water circulation in the Paratethys was strongly controlled by two shallow and narrow gateways: the Slovenian (Trans-Tethyan Trench) corridor (Rögl 1998; Kováč et al 2017) and the Bârlad Strait in Romania (Palcu et al 2015) connecting the Central and Eastern Paratethys Both gateways were located in tectonically active regions (Simon et al 2019) and controlled the recorded palaeoenvironmental changes in these basins, the exact mechanisms are still poorly understood (Palcu et al 2017). The Badenian Salinity Crises ended before 13.32 ± 0.07 Ma (de Leeuw (2020) 9:16

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