Biostratigraphy and paleoenvironmental reconstruction of the marine lower Miocene Chechiș Formation in the Transylvanian Basin based on foraminiferal assemblages

Abstract

Planktonic and benthic foraminiferal assemblages were used for biostratigraphy and paleoenvironmental reconstruction of the marine lower Miocene Chechiș Formation from the Gălpâia section (Sălaj county, Romania) in the northwestern Transylvanian Basin. Planktonic foraminifera suggest an Eggenburgian (Burdigalian) age for the deposits studied and reveal episodes of high primary productivity and mostly cool surface waters. Benthic foraminiferal assemblages indicate paleoenvironmental deepening from outer shelf to upper bathyal settings. Deltaic influences may be observed at the base of the studied section in outer shelf (possibly upper bathyal) environments with oxygenated bottom water and episodic high primary productivity, as a consequence of nutrient input from the land. Changes in paleobathymetry resulted in reduction of primary productivity. The benthic assemblages from the uppermost part of the section are dominated by tubular agglutinated foraminifera and indicate an upper bathyal setting with low organic flux to the sea floor. The sediments of the studied section were deposited during the late stage of the first early Miocene relative sea-level rise in the Transylvanian Basin. Key-words:• Foraminifera;

Microfacies and depositional environment of Tarbur Formation (Upper Cretaceous‐Lower Palaeocene) Zagros area, southwestern Iran

“…Recognition of agglutinated foraminifers is usually reported from the back shoals of a restricted to semi‐restricted system (Székely, Bindiu‐Haitonic, Filipescu, & Bercea, 2017). Reolid, Nagy, Rodríguez, and Olóriz (2008) obtained palaeoecological data (Bernhard, 1986; Nagy, 1992; Tyszka, 1994), which supported that agglutinated foraminifera infauna are assigned to a low‐level oxygenated environment.…”

Deep-water paleoenvironmental changes based on early-middle Miocene benthic foraminifera from Malta Island (Central Mediterranean)

“…Shallow infaunal (Pérez-Asensio et al, 2012). Species belonging to Bolivina spp., reported in Székely et al (2017) as lowoxygen group (Spezzaferri et al, 2002), which includes some species tolerating dysoxia (Murray, 2006); dysoxic species (Kaiho, 1994).…”

“…Species indicative of high productivity (Bellanca et al, 2002;Russo et al, 2007). Species tolerating dysoxia (Murray, 2006;Székely et al, 2017), and low oxygen conditions (Spezzaferri et al, 2002;Székely et al, 2017) since belonging to Bulimina spp. Species indicative of OMZ of eastern Arabian Sea, can be used as an index for delineating oxygen-depleted environments in Arabian Sea (Nigam et al, 2007).…”

“…Epifaunal (Murray, 2006;Székely et al, 2017). C. subhaidingerii: oxic (Corliss, 1991;Kaiho, 1994;Oblak, 2007;Russo et al, 2007;Sgarrella et al, 2012;Székely et al, 2017) and oligotrophic species, since belongs to Cibicidoides spp. generally preferring oxic and/or oligotrophic environments (Sgarrella et al, 2012).…”

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

“…2). In the last decade, a series of high-resolution biostratigraphic studies has been carried out (Beldean et al 2010(Beldean et al , 2012(Beldean et al , 2013de Leeuw et al 2013;Filipescu and Beldean 2007;Filipescu and Silye 2008;Székely et al , 2017. More detailed stratigraphic background data is found in Supplementary Data A and Sant et al (2019).…”