Geological Quarterly, 2017, 61 (4): 887–895 DOI: http://dx.doi.org/10.7306/gq.1379 Late Albian calcareous dinocysts and calcitarchs record linked to environmental changes during the final phase of OAE 1d – a case study from the Tatra Mountains, Central Western Carpathians Agnieszka CIUREJ 1 , Krzysztof BĄK 1, * and Marta BĄK 2 1 Pedagogical University of Cracow, Institute of Geography, Podchorążych 2, 30-084 Kraków, Poland 2 AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Al. Mickiewicza 30, 30-059 Kraków, Poland Ciurej, A., Bąk, K., Bąk, M., 2017. Late Albian calcareous dinocysts and calcitarchs record linked to environmental changes during the final phase of OAE 1d – a case study from the Tatra Mountains, Central Western Carpathians. Geological Quar- terly, 61 (4): 887–895, doi: 10.7306/gq.1379 Calcareous dinocysts and calcitarchs have been investigated for the first time within the Upper Albian limestone and marl succession of the Zabijak Formation from the High-Tatric Unit in the Tatra Mountains (Central Western Carpathians), related to the Oceanic Anoxic Event 1d (OAE 1d). Four groups of morphotaxa of calcareous dinocysts have been distinguished. They totally dominate the assemblages, and belong to the pithonellids. They are represented by Pithonella sphaerica (Kaufmann in Heer) and P. ovalis (Kaufmann in Heer), which dominate, as well as P. trejoi Bonet and P. lamellata Keupp in Keupp and Kienel, which are less abundant. Two other morphotaxa, Colomisphaera gigantea (Borza) and Cadosina oraviensis Borza, occur sporadically in the assemblages. Both forms represent the calcitarch group, which assembled calcispheres of unknown taxonomic affinity. The calcareous dinocyst and calcitarch diversity is low to moderate, compared to the general species richness known from Late Albian assemblages in other Western Tethyan sections. This is interpreted as a result of nutrient input fluctuations due to changes in the circulation pattern of surface and intermediate waters. The changes in the P. sphaerica/P. ovalis ratio along the Upper Albian section are here correlated with short-term (third-order) sea level fluctuations including transgressive and regressive events and a highstand. Pelletization processes might have in- fluenced cyst abundance on the sea floor, especially during periods with oligotrophic surface waters. Key words: calcareous dinocysts, calcitarchs, nutrient input and sea level fluctuations, Upper Albian, OAE 1d, Tatra Moun- tains. INTRODUCTION The Late Albian was a time of enhanced marine burial of sedimentary organic carbon as related to inorganic carbon, which is characterized by a positive excursion in d 13 C values in marine deposits, known from various Tethyan, North Atlantic, Pacific and epicontinental environments, and attributed to Oce- anic Anoxic Event 1d (e.g., Coccioni et al., 2001; Strasser et al, 2001; Kennedy et al., 2004; Bornemann et al., 2005; Jarvis et al., 2006; Gale et al., 2011; Papp et al., 2013; Scott et al., 2013; Horikx et al., 2014; Melinte-Dobrinescu et al., 2015). Such strata (a limestone and marl succession) with a positive d 13 C excursion, deposited on the northern shelf of the Alpine–Carpa- thian microcontinent, were also recorded from the Central Western Carpathians (the Tatra Mountains; Bąk et al., 2016). They contain marine and land-derived organic matter, strongly degraded under oxic conditions. These carbonate deposits, Late Albian in age, are enriched in calcareous dinocysts. How - ever, there are relatively few publications which deal with cal- careous dinocysts from the Cretaceous Tethyan realm of the Carpathians, with the exception of Upper Jurassic through Lower Cretaceous assemblages (mostly Tithonian–Aptian) re- corded in numerous Western Carpathian settings (e.g., Nowak, 1963, 1968, 1974; Borza, 1964, 1969, 1986; Řehánek, 1987; Reháková and Michalík, 1994, 1996; Lintnerová et al., 1997; Michalík et al., 1999, 2009; 2016; Reháková, 2000a, b; Pszczólkowski and Myczyński, 2004; Olszewska, 2005; Olsze- wska et al., 2008; Pszczólkowski et al., 2016). In this paper, we provide the first overview of calcareous dinocysts and calcitarchs, totally dominated by pithonellids from the Upper Albian carbonate deposits of the High-Tatric Unit in the Central Western Carpathians. Using new palaeontological data related to these microfossils from the Tatra Mountains, we make suggestions as to the possible environmental conditions prevailing on the northern shelf of the Alpine – Carpathian microcontinent (Fig. 1) that influenced the development of these organisms during the time corresponding to Oceanic Anoxic Event 1d. * Corresponding author, e-mail: sgbak@cyf-kr.edu.pl Received: February 13, 2017; accepted: July 29, 2017; first published online: September 11, 2017