Late Eifelian Kačák Episode in the epeiric Belarusian Basin: Role of terrestrial-marine teleconnections

Paleotemperature record of the Middle Devonian Kačák Episode

“…While the shallow marine carbonate platform setting (Val di Collina section) might have been affected by higher evaporation translating into higher δ 18 O seawater and thus higher δ 18 O apatite values, conodonts from pelagic deposits (Wolayer “Glacier” section) show lowest δ 18 O apatite values likely reflecting normal-marine more open ocean salinity and temperature. This documents that δ 18 O apatite values obtained from conodonts of tropical-subtropical shallow marine settings may not only represent seawater temperature but as well local salinity variations, as noted by several studies on δ 18 O apatite before 25 , 27 – 29 , 43 , 51 , 52 . Thus, exclusively δ 18 O apatite data from more open marine settings are used for calculation of mean paleotemperature.…”

“…Data of only two localities, at 34° S (ZMB section, Italy) and 36° S (Pic de Bissous sections, France), span the entire interval from the kockelianus until the hemiansatus Biozone. Additionally, δ 18 O apatite values from the epeiric Belarusian Basin (10–14° S) 28 , 29 , as well as those derived from conodonts of shallow marine deposits at 24° S 25 , 26 , 34°S (this study, Supplementary Fig. 2 ) and 36° S 25 are higher compared to values from conodonts of coeval more open marine habitats, contradicting expected values in relation to the latitudinal allocation.…”

“…2 ). This could be explained by regional salinity variations as suggested for localities between 10 and 14° S 28 , 29 or upwelling of colder intermediate waters in the Rheic Ocean 45 – 48 .…”

“…So far, paleotemperatures were published from southern hemisphere low latitudes between 10° and 36° S for localities in France (Pic de Bissous) 25 and Germany (Blankenheim, Hillesheimer Mulde, Schönecken-Dingdorf and Blauer Bruch) 25 , 26 . Additional data from Nevada, USA (northern Antelope mountains) documented a negative shift in the δ 18 O apatite during the onset of the LEE1 (upper part of the kockelianus Biozone) 27 , and more recently, paleotemperature reconstructions from Belarus were provided for the latest Eifelian interval ( ensensis Biozone) 28 , 29 .…”

Conodont stratigraphy and biodiversity of the Middle Devonian Kačàk Episode in the Pic de Bissous (Montagne Noire, S-France)

“…The latest Eifelian Kačák Episode (KE) is one of several Devonian turning points marked by black-shale levels, such as the Kellwasser or Hangenberg events (Walliser 1996;House 2002; Kabanov and Jiang 2020). Recently, Narkiewicz et al (2021) stressed its signi cance for understanding climatic and biotic geosystem perturbations, including global warming, humidization, eustatic events and development of incipient forests. Also, the crucial role of conodonts in a global correlation of KE has been reviewed and discussed as well as their importance in studying environmental aspects of the episode (Narkiewicz et al 2023).…”