Olenekian (Early Triassic) foraminifers of the Gorny Mangyshlak, Eastern Precaucasus and Western Caucasus

A new Early Triassic (Olenekian) foraminiferal assemblage has recently been discovered in the Gorny Mangyshlak in the Caspian Sea region. The Triassic foraminiferal assemblages of the Western Caucasus and Eastern Precaucasus are similar to those present in the Gorny Mangyshlak. Widely distributed species of foraminifers, conodonts, and ammonoids occur in the Lower Triassic of all three of those regions. Therefore, it is possible to correlate the Olenekian foraminiferal assemblage of the Gorny Mangyshlak to the Meandrospira pusilla assemblage in other parts of the world, and to the global stratigraphic scale.The Olenekian foraminiferal assemblage of the Gorny Mangyshlak mainly consists of primitive attached foraminifers and diverse nodosariids. Such a foraminiferal assemblage usually indicates adverse paleoenvironmental conditions for benthic fauna. The taxonomic composition of the Olenekian foraminiferal assemblages from the Gorny Mangyshlak and Caucasus regions allows us to conclude that these faunas are similar to the foraminiferal assemblages from the Carpathians and Balkans. It is possible that the paleobasins of these regions had good connections and foraminifers migrated between these regions. The late Olenekian transgression provided conditions for the existence of different groups of macrofaunas and foraminifers to develop in these basins. The late Olenekian transgression allowed the biota from the Caucasus paleobasin to move into the paleobasin of Central Asia (Mangyshlak). Similarities of the Early Triassic biotic assemblages of the Caucasus and Gorny Mangyshlak to coeval strata in Europe are demonstrated.