Lower triassic (Olenekian) microfauna from Jadar block (Gučevo mt., Nw serbia)

Abstract

Systematic study of microfossil associations on the Krivi Potok section (Gučevo Mt. area, NW Serbia) has been carried out to document and to refine the Lower Triassic stratigraphic correlations within Alpine-Mediterranean domain. Field investigation and laboratory process have enabled the identification of lowermost Olenekian (lower Smithian) conodonts, ostracodes and pyrite framboids. Two conodont zones are established in this region, in ascending order they are: Pachycladina obliqua-Foliella gardenae Assemblage Zone and Neospathodus planus Zone. A new ostracode species Paracypris ? krivipotokensis FOREL n. sp. has been described, it co-occurs with conodont Neospathodus planus within the Zone of the same name. The pyrite framboids were formed within the ostracode carapaces after their death. The size distribution of pyrite framboids supports the former suggestion that large size (>6 μm in diameter) is not suitable for the reconstruction of seawater redox conditions.

Keywords

• Lower Triassic
• Olenekian
• conodonts
• ostracodes
• pyrite framboids
• Jadar Block
• Northwestern Serbia