Late Cenomanian environmental conditions at the submerged Tatric Ridge, Central Western Carpathians during the period preceding Oceanic Anoxic Event 2 – A palaeontological and isotopic approach

Termination of Organic-Rich Accumulation of the Oceanic Anoxic Event 2 in the Deep-Water Carpathian Basins Based on Carbon Stable Isotope Data

“…Its stratigraphic position was defined as very close to the first occurrence of the ammonite Watinoceras devonense and calcareous nannoplankton Quadrum gartneri, recognized in many sections where accumulation of CTBI sediments occurred above CCD (e.g., [45,[51][52][53][54][55]). 13 C org events between Outer Carpathian basins, Umbria-Marche Basin, Central Atlantic, and southern peri-Tehyan shelf. The curves representing Outer Carpathian sections are compared using chemostratigraphic markers with age-calibrated sections from other regions.…”

“…1.5 m below the top of this succession (red line on Figure 3) may provide a marker point for both curves. The onset of the positive excursion related to the OAE2 lies within the argillaceous part of the organic-rich facies (point "A"; Figure 3); δ 13 C org values increase rapidly by about 2-2.4‰ within a 50-centimeter-thick interval, reaching a maximum at the first black shale layer of the siliceous part of this facies (point "B"; Figure 3).…”

“…It seems that the time interval for such accumulation in the Western Tethys was similar, however, the stratigraphic correlation of this phenomenon is not unequivocal and easy, especially for deep environments below CCD, due to lack of calcareous microfossils. An example of such environment were marginal basins in the Carpathian domain, where the CTBI record containing the Bonarelliequivalent Level was studied in detail based on deep-water agglutinated foraminifers (DWAF), radiolarians [11], and using chemical indices (summary in [3,12,13]).…”

Biostratinomy and Diagenetic Impact on Exceptional Preservation of Coccospheres from Lower Oligocene Coccolith Limestones

“…It could have been related to existence of oxygen minimum zone widely dispersed in the water column in the central Paratethys [25,46,[73][74][75]. Unlike oxygenated water column, where organic-rich aggregates are rapidly consumed by detritivores and micro-organisms at the sediment/water interface [76], the anoxic conditions were an important factor for the preservation of fecal pellets and aggregates [77,78]. Such conditions could prevail during most of the Oligocene in the central Paratethys Basin which was a landlocked, marginal sea, where stagnation and oxygen deficiency prevailed in deep water [25].…”

Palaeoceanographic regime during the Oxfordian–Kimmeridgian in the Western Tethys recorded by radiolarian assemblages in the siliceous sediments of the Pieniny Klippen Belt, Carpathians

“…Little is known about the causes of the high radiolarian abundance during this time. The most accepted interpretations explaining this phenomenon are shallow calcite compensation (e.g., Garrison, ; Grunau, ), high surface water fertility and eutrophication over upwelling zones (e.g., Bernoulli & Jenkyns, ; Danelian et al, ; De Wever et al, , ; Jenkyns & Winterer, ), oligotrophic conditions due to Caribbean‐like river plumes (Baumgartner, ), lateral redeposition of radiolarian tests from topographic highs into basin troughs (Baumgartner, ), a circulation pattern controlled by tectonic processes (Muttoni, Erba, Kent, & Bachdadse, ), pellet production (M. Bąk, ; K. Bąk, Bąk, Dulemba, & Okoński, ), and their preservation during sinking in the water column (K. Bąk, Fabiańska, et al, ; M. Bąk & Sawłowicz, ). In fact, most of these interpretations have been employed to reconstruct only the general mechanism of radiolarian enrichment during Middle–Late Jurassic siliceous deposition.…”