Ichno-and body-fossils from the Upper Triassic-Lower Jurassic Sinivir Formation in the Balaban Dere Valley (East Strata Planina Mts, east Bulgaria) and the problem of the Triassic/Jurassic boundary

The Triassic and Jurassic sediments in East Stara Planina Mts. are of two types: (a) parautochtonous - relatively deep marine sediments, Tethyan type, and (b) allochtonous - shallow marine deposits, Peri-Tethyan type (included in the first as olistolites). The parautochtonous type had been sedimented in unilateral rift-basin, and the allochtonous type - on the shelf, connecting the basin with the dry land to the South. The Glogova Fm. (Upper Carnian (p. p.) - Norian (p. p.), and Sinivir Fm. (Norian (p. p.) - Toarcian (p. p.) are studied here. They are related to a progressive transition and contain deep-water ichnofossils – Nereites ichnofacies. Middle Norian bivalves – Monotis salinaria salinaria, and Monotis cf. salinaria haueri are collected in the lower parts of Sinivir Fm., and higher - fragments of Jurassic belemnites. In a nearby section spores and pollens of Late Pliensbachian Ischyosporites variegates/Matonisporites crassiangulatus Biointerval Zone, dinocystes as Nannoceratopsis gracilis (Pliensbachian - Middle Bathonian), which indicate Spheripollenites subgranulatus Acme-Zone, as well as Liassic foraminifers Ammodiscus infimus, Annulina metensis, etc. are collected. The boundary Triassic/Jurassic, in deep water conditions, is located in Sinivir Fm. and is connected with progressive transition, whilst in shelf conditions the boundary is related to a break in the sedimentation.