TY - JOUR

T1 - The Ammonite Catacadoceras barnstoni Beds and the Problem of the Separation of the Middle and Upper Substages of the Bathonian Stage in Northern Siberia

AU - Shamonin, E. S.

AU - Knyazev, V. G.

AU - Dzyuba, O. S.

N1 - The study was supported by the Russian Science Foundation (grant no. 22-17-00228, https://rscf.ru/project/22-17-00228/ , at Trofimuk Institute of Petroleum Geology and Geophysics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk. The geological structure of the northern Chekurovka section was studied in the course of the fieldwork supported by the Russian Ministry of Education and Science (projects FUUM-2019-0004, FWZZ-2022-0004, IPGG SB RAS, Novosibirsk; budget project, Diamond and Precious Metal Geology Institute of the Siberian Branch of the Russian Academy of Sciences (DPMGI SB RAS), Yakutsk).

PY - 2023/8

Y1 - 2023/8

N2 - The taxonomic composition of the ammonite family Cardioceratidae is studied in the Bathonian of northern Siberia in the range of distribution of the last representatives of the genus Arcticoceras and the first representatives of the genus Catacadoceras, aiming to solve the problem of the Middle-Upper Bathonian boundary. It is shown that all previous identifications of northern Siberian material as the Middle Bathonian species Arcticoceras cranocephaloide Callomon et Birkelund, 1985, were incorrect. The misidentified specimens were mainly the Late Bathonian ammonite species Catacadoceras barnstoni (Meek, 1859) or the form with a narrow umbilicus referred to herein as Cat. aff. barnstoni. An updated ammonite zonal scale of the Middle–Upper Bathonian of Siberia is proposed, which is recommended for use both in the regional stratigraphic schemes of the Jurassic deposits of Eastern (Middle) Siberia and in the Boreal (Siberian) zonal standard of the Bathonian Stage. The extreme importance of preserving an auxiliary biostratigraphic subdivision in this scale, the Cat. barnstoni Beds, is emphasized, because of the wide distribution and abundance of the index species in Siberian sections, as well as its significance for the correlation of the lower part of the Upper Bathonian of northern Canada, northern Siberia, Franz Josef Land, and East Greenland. In addition, two intervals, i.e., the interval with Cat. aff. barnstoni and interval with Cat. perrarum, are fixed as marker levels, which are useful for rapid age determination and correlation of the Upper Bathonian deposits in Arctic sections within the upper part of the Cat. barnstoni Beds.

AB - The taxonomic composition of the ammonite family Cardioceratidae is studied in the Bathonian of northern Siberia in the range of distribution of the last representatives of the genus Arcticoceras and the first representatives of the genus Catacadoceras, aiming to solve the problem of the Middle-Upper Bathonian boundary. It is shown that all previous identifications of northern Siberian material as the Middle Bathonian species Arcticoceras cranocephaloide Callomon et Birkelund, 1985, were incorrect. The misidentified specimens were mainly the Late Bathonian ammonite species Catacadoceras barnstoni (Meek, 1859) or the form with a narrow umbilicus referred to herein as Cat. aff. barnstoni. An updated ammonite zonal scale of the Middle–Upper Bathonian of Siberia is proposed, which is recommended for use both in the regional stratigraphic schemes of the Jurassic deposits of Eastern (Middle) Siberia and in the Boreal (Siberian) zonal standard of the Bathonian Stage. The extreme importance of preserving an auxiliary biostratigraphic subdivision in this scale, the Cat. barnstoni Beds, is emphasized, because of the wide distribution and abundance of the index species in Siberian sections, as well as its significance for the correlation of the lower part of the Upper Bathonian of northern Canada, northern Siberia, Franz Josef Land, and East Greenland. In addition, two intervals, i.e., the interval with Cat. aff. barnstoni and interval with Cat. perrarum, are fixed as marker levels, which are useful for rapid age determination and correlation of the Upper Bathonian deposits in Arctic sections within the upper part of the Cat. barnstoni Beds.

KW - Arctic

KW - Cardioceratidae

KW - Middle Jurassic

KW - ammonites

KW - biostratigraphy

KW - interregional correlations

UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85165298527&origin=inward

UR - https://www.mendeley.com/catalogue/137dc848-4d18-316c-a984-1c4ada6f26ba/

U2 - 10.1134/S0869593823040032

DO - 10.1134/S0869593823040032

M3 - Article

VL - 31

SP - 275

EP - 298

JO - Stratigraphy and Geological Correlation

JF - Stratigraphy and Geological Correlation

SN - 0869-5938

IS - 4

ER -