TRIASSIC STRATIGRAPHY OF THE NORTHERN CAUCASUS BASED ON AMMONOIDS

Field investigations and bed-by-bed sampling of ammonoids provide the basis for a more detailed and better constrained biostratigraphic sche me of Triassic deposits in the northern Caucasus. For the first time, these deposits are subdivided into ten ammonoid beds comprising the Tr iassic interval from the middle Scythian to the upper Rhaetian. The be ds are correlated with the standard ammonoid zones. The Anisian deposi ts, which are especially rich in ammonoids, are correlated with synchr onous sedimentary sections in Turkey, Iran, China, and the USA. New da ta elucidate that in the studied, region there is a considerable strat igraphic hiatus spanning the upper Anisian and the lower Ladinian.