Integrated biostratigraphic, palaeoenvironmental and wireline log characterisation of upper Miocene to lower Pliocene successions of the eastern Dacian Basin (SE Romania)

Palaeovegetation and palaeoclimate evolution during the Late Miocene to Early Pliocene of SE Romania

“…As part of the Eastern Paratethys, the Dacian Basin underwent a gradual decrease in marine influence during the Late Miocene to Early Pliocene, which was only interrupted by brief episodes of marine incursions (Jipa et al, 2007; Krijgsman, Stoica, Vasiliev, & Popov, 2010; Stoica et al, 2013; Stoica et al, 2007). At least two of these marine flooding events, at the Khersonian–Meotian and the Meotian–Pontian boundaries, have been recorded in the studied successions and are represented by influxes of benthonic foraminifera (Figure 2; Casas‐Gallego et al, 2020). During the Pontian, shallow, brackish depositional settings prevailed in the area.…”

“…Five 1‐ to 1.5‐km‐thick sedimentary successions were sampled by Hunt Oil Company of Romania (HOCOR) during the routine drilling operations of onshore wells in the Dacian Basin. The successions are chronologically constrained by means of micropalaeontology (benthonic foraminifera, molluscs, and ostracods) and dinoflagellate cysts (Casas‐Gallego et al, 2020). The Khersonian, Meotian, Pontian, and Dacian regional stages are represented in the studied sequences, which cover a time span of more than 6 Ma of continuous sedimentation (Figure 2).…”

“…Lithological log of the five studied sections indicating the position of the samples analysed for palynology and the main palaeoenvironmental events used to constrain the chronostratigraphy and to carry out the stratigraphic correlation of the successions (Casas‐Gallego et al, 2020) [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…In the Eastern Paratethys, the Dacian Basin became isolated from the Mediterranean realm during the Bessarabian (Tortonian, ca. 11.6 Ma; Palcu et al, 2017), starting a trend from marine settings towards shallower and freshwater conditions, interrupted by episodic marine water incursions, which culminated in the Dacian (Zanclean; Casas‐Gallego et al, 2020; Jipa & Olariu, 2009; Jipa, Olariu, Marinescu, Olteanu, & Brustur, 2007; Stoica et al, 2013; Stoica, Lazăr, Vasiliev, & Krijgsman, 2007). All these climatic and palaeogeographical processes greatly affected the vegetation in the region (Jiménez Moreno, Popescu, Ivanov, & Suc, 2007; Țabără, 2014; Ţabără & Chirilă, 2012a).…”

Biostratigraphic re-evaluation of the lower to middle Miocene succession in the Eastern Carpathians: a case study related to the oil fields of the Diapir Fold Zone, Romania

“…A few taxa give clear mid dle-up per Mio cene ages, such as Achomosphaera crassipellis Deflandre and Cookson, A. alcicornu Eisenack, Palaeocystodinium miocaenicum Strauss et al, and Phtanoperidinium mucronatum Hope (Lubenescu et al, 1986;Köthe and Piesker, 2007;Bakraè et al, 2012). Sev eral sam ples, pre vi ously assigned in lab re ports to the Oligocene to early Mio cene in ter val, con tain palynological as sem blages typ i cal of mid dle to up per Mio cene de pos its of the Dacian Ba sin (Ro man and Papaianopol, 1982;£abãrã, 2008, 2014, Casas-Gallego et al, 2020a, mainly gym no sperms (Pinuspollenites, Piceapollis, Abiespollenites, Taxodiaceae) and an gio sperms (e.g., Tricolporopollenites, Caryapollenites, Quercopollenites, Faguspollenites, Sabalpollenites, Tiliapollenites, Alnipollenites, Chenopodiaceae). Among the spores con sid ered as mark ers for the early Mio cene, Mecsekisporites mioceanicus Nagy mainly oc curs in the mid dle Mio cene (Badenian) of the Pannonian Ba sin (Nagy, 2005;Mandic et al, 2019).…”