Paleoceanography and climate of the Badenian (Middle Miocene, 16.4–13.0 Ma) in the Central Paratethys based on foraminifera and stable isotope (δ18O and δ13C) evidence

Abstract

Benthic foraminifera and stable isotopes analyses revealed changes emerging in the paleoceanographic scenery in the Paratethys. The percentage of inbenthic, oxyphylic taxa and diversity in the benthic foraminiferal assemblage showed increasing food supply (organic matter), decreasing oxygen level and growing stress on the sea floor. Oxygen isotopes measured in planktonic and benthic foraminifera pointed to strengthening stratification during the Badenian period. The carbon isotopes indicated intensified accumulation of light marine organic matter. This increasing stratification trend is especially pronounced by Late Badenian (13.5-13 Ma) when surface water oxygen isotope values are rather negative. A simple two-layer circulation model was worked out for the Badenian Paratethys explaining these characteristic environmental changes. An antiestuarine (lagoonal) circulation is assumed for the Central Paratethys during the Early (16.4-15 Ma) and mid Badenian (15-13.5 Ma). The mid Badenian period of time comprises the short episode of evaporite formation in the Carpathian Foredeep and the Transylvanian Basin. Evidence presented here supported a reversal of circulation to estuarine type after the deposition of salts by Late Badenian (13.5-13 Ma). The Early Badenian antiestuarine circulation is suggested to associate with the high temperatures of the Mid-Miocene Climatic Optimum, and the Late Badenian estuarine circulation with the cooler period following it.

New Middle Miocene Bryozoa from Gârbova de Sus (Romania) and their relationship to the sedimentary environment

“…For classification of individual species to the above mentioned groups, the data of Murray (1991Murray ( , 2006, Kaiho (1994Kaiho ( , 1999, de Stigner et al (1998), den Dulk et al (1998), den Dulk et al (2000), Spezzaferri et al (2002) and Báldi (2006) were used. Estimation of paleotemperature changes in the upper layer of water column was based on the ratio between cool-and warm-water species of planktonic foraminifera (Spezzaferri & Ćorić 2001;Spezzaferri et al 2002;Bicchi et al 2003;Rupp & Hohenegger 2008).…”

Coiling direction in Middle Miocene globorotaliids (Foraminiferida) – a case study in the Paratethys (Upper Silesia Basin, Poland)

“…In spite of the var i ous names used for the par tic u lar Badenian biozones within the Cen tral Paratethys, they show con sis tency and can be readily traced through out this area (e.g., Steininger et al, 1985;Popescu and Brotea, 1994;Cicha et al, 1998;£uczkowska, 1998;Báldi, 2006;Doláková et al, 2014;Báldi et al, 2017).…”

Biostratigraphy and paleoecology of the Burdigalian-Serravallian sediments in Wadi Sudr (Gulf of Suez, Egypt): comparison with the Central Paratethys evolution

“…(iv) Relative abundances of infaunal species (Murray 1991(Murray , 2006Spezzaferri et al 2002;Báldi 2006).…”

“…Oxic and dysoxic indicators were classified according to Kaiho (1994Kaiho ( , 1999, den Dulk et al (2000); Spezzaferri et al (2002) and Báldi (2006).…”

“…where P is the number of planktonic foraminifers, Bt is the total number of benthic foraminifers and Bi is the number of deep infaunal species (van der Zwaan et al 1990;van Hinsbergen et al 2005;Báldi 2006) which are excluded from analysis because they are not directly dependent on the flux of organic matter to the sea floor. The P/B-ratio is not only influenced by depth, but also by changes in the oxygenation of bottom waters (Sen-Gupta & Machain-Castillo 1993;Jorissen et al 1995) which may fluctuate (Kouwenhoven et al 2003).…”