PARALLEL BIOSTRATIGRAPHIC SCALES OF THE BOREAL BATHONIAN AND CALLOVIAN IN THE NORTH PECHORA REGION AS A TOOL FOR INTERREGIONAL CORRELATIONS

Investigation results on ammonites, belemnites, and dinoflagellate cys ts from Bathonian and Callovian deposits in the North Pechora region a re used to elaborate the detailed stratigraphy and to correlate these deposits in the northern West Europe and Siberia. The Pechora basin, w hich was located in Jurassic time at the boundary between the Arctic a nd Boreal Atlantic paleobiogeographic provinces, incorporates faunas t ypical of neighboring regions and thus is an intermediate province lin king Siberia with West Europe. The bed-by-bed study of sections expose d along tributaries of the Pechora River provided grounds to elaborate the Bathonian-Callovian biozonation of ammonites, belemnites, and din oflagellate cysts. The ammonite zonation consisting of eleven units is correlated with the West European standard and East Siberian local zo nations, The identified common species suggest that Pechora sections i nclude the standard zigzag, herveyi, calloviense, athleta, and lambert i zones. Other units bearing only the arctic species are correlated wi th Bathonian and Callovian ammonite zones established in eastern and w estern Siberia. The revealed belemnite zonation includes five biostrat igraphic units spanning the middle Bathonian and entire Callovian inte rvals. It is correlated with the regional ammonite scale and also with the East Siberian belemnite zonation. The Bathonian-Callovian success ion of dinocysts assemblages is shown to include seven units ranked as zones or dinocyst beds. The dinocyst assemblages from Bathonian and C allovian deposits of the North Pechora and other regions of the Russia n platform, along with similar assemblages from northern Siberia, are calibrated by comparison with dinoflagellate zonations in northwestern Europe and Arctic Canada. The mutually coordinated Bathonian-Callovia n zonation of ammonite, belemnite, and dinocyst fossils is suggested t o be a reliable biostratigraphic scale for interregional correlations in a vast area of northern Eurasia, Arctic regions, and America. The p aper also includes description of Cadoceras pishmae Meledina, C. varia bile Spath (ammonites), and Belemnopsis sp. ind.