The mid-Langhian flooding in the eastern Central Paratethys: integrated stratigraphic data from the Transylvanian Basin and SE Carpathian Foredeep

K Sant,T Kouwenhoven,A Di Stefano,K F Kuiper,E Turco,W Krijgsman,D V Palcu,N Baldassini

doi:10.1007/s00531-019-01757-z

K Sant, T Kouwenhoven + Show 6 more

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https://doi.org/10.1007/s00531-019-01757-z

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Abstract

The mid-Langhian (“Badenian”) flooding fully reconnected the semi-isolated Central Paratethys realm with the Mediterranean and, thereby, drastically changed the middle Miocene paleogeography of Central Europe. Due to the scattered stratigraphic record and scarcity of independent age constraints in some areas, the precise age and underlying mechanism are still debated. We present integrated chronostratigraphic data from five sections in the eastern part of the system to reconstruct the flooding event distal from the strait to the Mediterranean. By applying modern Mediterranean biochronology (planktonic foraminifera and calcareous nannofossils), supplemented by an 40Ar/39Ar age on a tuff, we demonstrate that the widespread open marine settings in the NW Transylvanian Basin were definitely installed after 14.9 Ma (MMi4d biozone), and in most areas before 14.4 Ma. In the marginal study area in the SE Carpathian Foredeep, fully marine conditions likely set in slightly later (14.6–14.4 Ma). There, short-lived marine incursions into the brackish environment occurred since the latest Burdigalian (“pre-flooding phase”). The new ages overlap with the flooding in the majority of the Central Paratethys (~ 14.9–14.4 Ma), and with marine overflow into the Black Sea (14.85 Ma). We suggest that the transgression was driven by subsidence of the Pannonian Basin, by creating accommodation space and diminishing barriers between sub-basins, but was likely enhanced by a global sea-level rise. Finally, we speculate that the scarcity of all calcareous material in the SE Carpathian Foredeep before the mid-Langhian flooding might be related to pulses of nutrient-rich brackish and low pH water from the neighboring Black Sea Basin.

Highlights

During the Miocene, a large part of Central Europe was covered by the Paratethys Sea (Popov et al 2004; Rögl 1998)
The presence of pyrite (FeS2) throughout the majority of the sections suggests that sub-oxic to anoxic bottom conditions occurred frequently in the N Transylvanian Basin and SE Carpathian foredeep during the studied period (Berner 1970, 1984; Rickard and Luther 2007)
By applying the most recent Mediterranean biochronology, we show that marine incursions into the dominantly brackish basins of Central Europe occurred at least since the latest Burdigalian

Summary

Introduction

During the Miocene, a large part of Central Europe was covered by the Paratethys Sea (Popov et al 2004; Rögl 1998). Numerous independent age constraints have been produced by integrated stratigraphic methods in the last decade (e.g., Mandic et al 2012; de Leeuw et al 2013; Palcu et al 2015; Sant et al 2018). These allowed quantitative reconstructions of major tectonic and climatic events affecting the whole area, such as the Badenian Salinity Crisis (de Leeuw et al 2010), the Badenian-Sarmatian Extinction Event (Harzhauser and Piller 2004; Palcu et al 2015) and late Miocene installation of Lake Pannon (Filipescu et al 2011; Magyar et al 1999; ter Borgh et al 2013; Vasiliev et al 2010)

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