HR: 11:20h
AN: GP52A-05    [Abstracts]
TI: The First Boreal-Tethyan Correlation of the Jurassic-Cretaceous Boundary Interval by the Magnetostratigraphy
AU: * Pruner, P
EM: pruner@gli.cas.cz
AF: Institute of Geology AS CR, Rozvojova 269, Praha, 165 00, Czech Republic
AU: Housa, V
EM: housa@gli.cas.cz
AF: Institute of Geology AS CR, Rozvojova 269, Praha, 165 00, Czech Republic
AU: Zakharov, V
EM: zakharov@ginras.ru
AF: Geological Institute RAS, Pyzhevski Lane 7, Moscow, Russian Federation
AU: Kostak, M
EM: kostak@natur.cuni.cz
AF: Faculty of Science Charles University, Albertov 6, Praha, 128 43, Czech Republic
AU: Chadima, M
EM: chadima@gli.cas.cz
AF: Institute of Geology AS CR, Rozvojova 269, Praha, 165 00, Czech Republic
AU: Rogov, M
EM: rogov@ginras.ru
AF: Geological Institute RAS, Pyzhevski Lane 7, Moscow, Russian Federation
AU: Slechta, S
EM: slechta@gli.cas.cz
AF: Institute of Geology AS CR, Rozvojova 269, Praha, 165 00, Czech Republic
AU: Mazuch, M
EM: mazuch@natur.cuni.cz
AF: Faculty of Science Charles University, Albertov 6, Praha, 128 43, Czech Republic
AB: Climatic zoning as well as some peculiarities of paleoceanography, existed during the Late Jurassic and Early Cretaceous in the Northern Hemisphere, lead to formation of the significant differences in the taxonomic structure of south and north marine and terrestrial biota and to restriction of two main superrealms: southern Tethys- Panthalassa and northern Panboreal. For the purpose of liquidation of this gap authors undertook joint bio- and magnetostratigraphic studies of the Jurassic-Cretaceous boundary beds, situated at the Nordvik peninsula, northern Siberia (GACR 205-07-1365). Key interval for paleomagnetic sampling of the section, with a thickness of 27 m, has been determined by using biostratigraphy from top part of Middle Volgian (Epivirgatites variabilis Zone) until lowermost Ryazanian (Hectoroceras kochi Zone). As results of these investigations well-founded version of magnetostratigraphic correlation of J/K boundary beds has been supposed for the first time for those distant regions as Southern Europe and Northern Siberia. The Nordvik section is contain of magnetozones ranging from M20n to M17r and two narrow reverse subzones M20n.1r "Kysuca Subzone" in M20n, and M19n.1r "Brodno Subzone" in M19n. Their positions are within normal magnetozones, one inside of lower N-magnetozone and the second in the youngest part of the middle N-magnetozone. In the previously studies analogous two narrow reverse subzones ("Kysuca" and "Brodno") were detected in M20n and M19n and precisely defined in the Brodno (West Slovakia), Puerto Escaño (South Spain), Bosso Valley (Central Italy) and are well correlated with the M- sequence of marine magnetic anomalies. The determination of both reverse Subzones enabled the distinction of individual polarity zones in the Nordvik section with chrons M20 and M19. Identical to analogy of the Kysuca Subzone detected in normal magnetozone M20n is only 7cm thick. According to the Brodno profile, it is situated above the middle of normal magnetozone M20n. Another reverse subzone called the Brodno Subzone, detected in the upper part of normal magnetozone M19n, is 17cm thick. New magnetostratigraphic data obtained by us from Boreal (Arctic) section were compared with the analogous materials from the J/K boundary beds of the Tethyan character. The research showed that the Boreal J/K boundary is much younger than the Tethyan - both boundaries lay in different paleomagnetic zones.
DE: 1520 Magnetostratigraphy
DE: 9320 Asia
DE: 9335 Europe
DE: 9610 Cretaceous
DE: 9611 Jurassic
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly