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Further observations on the bio- and magnetostratigraphy of the J/K boundary interval in southern Ukraine

Wimbledon William A.P., Svobodova Andrea, Bakhmutov Vladimir, Poliachenko Ievgen, Hlavatskyi Dmytro

Geological Quarterly

2022

Vol. 66, No. 1

art. no. 11

This is an account of finds of stratigraphically useful calcareous nannofossils and the magnetostratigraphy of the Jurassic-Cretaceous boundary interval of the eastern Crimean peninsula (southern Ukraine). We compare these new complementary results with those presented by our team in earlier publications. A missing interval in the Crimean sequence is filled, and the position of the Tithonian-Berriasian (J/K) boundary is confirmed.

The proposal of a GSSP for the Berriasian Stage (Cretaceous System): Part 1

Wimbledon William A.P., Reháková Daniela, Svobodová Andrea, Elbra Tiiu, Schnabl Petr, Pruner Petr, Šifnerová Krýstina, Kdýr Šimon, Dzyuba Oksana, Schnyder Johann, Galbrun Bruno, Košťák Martin, Vaňková Lucie, Copestake Philip, Hunt Christopher O., Riccardi Alberto, Poulton Terry P., Bulot Luc G., Frau Camille, De Lena Luis

Volumina Jurassica

2020

Vol. 18, no. 1

53--106

Here in the first part of this publication we discuss the possibilities for the selection of a GSSP for the Berriasian Stage of the Cretaceous System, based on the established methods for correlation in the Tithonian/Berriasian interval. This will be followed, in the second part, by an account of the stratigraphic evidence that justifies the locality of Tré Maroua (Hautes-Alpes, SE France) as the proposed GSSP. Here we discuss the possibilities for correlation in the historical J/K boundary interval, and the evolution of thinking on the positioning of the boundary over recent generations, and in relation to research in the last ten years. The Tithonian/Berriasian boundary level is accepted as occurring within magnetosubzone M19n.2n. The detailed distribution of calpionellids has been recorded at numerous sites, tied to magnetostratigraphy, and the base of the calpionellid Alpina Zone is taken to define the base of the Berriasian Stage. This is at a level just below the distinctive reversed magnetic subzone M19n.1r (the so-called Brodno reversal). We discuss a wide range of magnetostratigraphic and biostratigraphic data from key localities globally, in the type Berriasian areas of France and wider regions (Le Chouet, Saint Bertrand, Puerto Escaño, Rio Argos, Bosso, Brodno, Kurovice, Theodosia etc.). The characteristic datums that typify the J/K boundary interval in Tethys and its extensions are detailed, and the correlative viability of various fossil groups is discussed. The boundary level is correlated to well-known J/K sections globally, and a series of secondary markers and proxies are indicated which assist wider correlation. Particularly significant are the primary basal Berriasian marker, the base of the Alpina Subzone (marked by dominance of small Calpionella alpina, Crassicollaria parvula and Tintinopsella carpathica) and secondary markers bracketing the base of the Calpionella Zone, notably the FOs of the calcareous nannofossil species Nannoconus wintereri (just below the boundary) and the FO of Nannoconus steinmannii minor (just above). Notable proxies for the boundary are: 1) the base of the A rctoteuthis tehamaensis Zone in boreal and subboreal regions, 2) the dated base of the Alpina Subzone at 140.22 ±0.14 Ma, which also gives a precise age estimate for the system boundary; and 3) the base of radiolarian “unitary zone” 14, which is situated just above the base of the Alpina Subzone.

Biostratigraphy, magnetostratigraphy, C and O isotope distribution around the J/K boundary, the Brodno section (Kysuca Unit of the Pieniny Klippen Belt)

Michalik J., Rehakova D., Halasova E., Lintnerova O.

Volumina Jurassica

2006

Vol. 4, no. 1

190-191

Detailed litho- and biostratigraphy of the Brodno section in contact zone of the Outer and the Central Western Carpathians was given by Michalík et al. (1990), VaĘíçek et al. (1992). Kimmeridgian and Tithonian condensed sequence of red nodular limestones (the Ammonitico Rosso facies) is referred to as the Czorsztyn Limestone Fm. Calcareous dinoflagellates Carpistomiosphaera borzai and Stomiosphaera moluccana indicate its Kimmeridgian age; Parastomiosphaera malmica, Carpistomiosphaera tithonica and Colomisphaera pulla indicate Early Tithonian age; calpionellids Chitinoidella boneti, Praetintinnopsella andrusovi, Crassicollaria intermedia, Crassicollaria brevis, Crassicollaria parvula, Crassicollaria colomi, confirm Middle to Late Tithonian age of this formation. Lower Berriasian part of this succession is represented by pale biomicritic wackestone (Pieniny Limestone Fm) with abundant Calpionella alpina. Strong subsidence and acceleration of “planktic rain” of nannofossils started on the Early/Middle Tithonian boundary where Polycostella beckmannii appeared. Helenea chiastia together with first small nannoconids are typical of the Middle and Late Tithonian. The Late Tithonian interval was specified by the FO of Rotelapillus laffitei and Litraphidites carniolensis. The Tithonian/Berriasian boundary was characterized by the FO of Nannoconus wintereri together with small nannoconids and by the FO of Nannoconus steinmanni minor. There is good correlation between the calcareous nannofossils distribution and the magnetostratigraphic zonation (HouĘa et al. 1996). In the M 20-M 19 interval, two distinct nannoevents were recognized: the dominance of Polycostella beckmannii (Chitinoidella Zone) and the appearance of calcareous nannofossil association with Helenea chiastia (Crassicolaria Zone). Carbon isotope curve from bulk carbonates of the J/K boundary sequence shows smooth trends resulted from equilibrated measure of bio-productivity and organic matter burial. The ä13C value ranges from 1.3 to 1.5‰ (PDB). The authentic character of the limestone record is underlined by relative high and conservative ä18O values (-2.27 to -0.88) of the same beds. These signals can be useful in global stratigraphic correlation in deep water carbonates.