THE BARREMIAN/APTIAN BOUNDARY IN THE SOUTH CARPATHIANS (ROMANIA)

A continuous marine sedimentation occurred in many areas from Romania within the Barremian/Aptian Boundary Interval. Some of the best exposures are located in the eastern part of the South Carpathians, in the Dambovicioara area. The Upper Barremian is there characterized by the Urgonian facies: reefal limestones, with rich tethyan ammonite assemblages and common occurrence of benthonic foraminifera of the miliolid group. The reefal limestones are overlain by a marly dominated sequence, uppermost Barremian in age. This one contains, besides tethyan macrofaunas and nannofloras, a small group of boreal taxa, indicating probably an uppermost Barremian trangression. The Barremian/Aptian Boundary was located, based on palaeontological data (Patrulius & Avram, 1976, Avram & Melinte, 1998) at the base of a bed of calcarenite, 1m thick, very rich in orbitolinids. To note that the lowermost Aptian succession (the first beds above the orbitolonid acme) from the Romanian Carpathians lack Deshayesites, as well as other areas from Tethys (e.g. Basses Alpes, France-Thomel 1964). The nannofloral character, dominated by tethyan species, together with a facial recurrence (limestone-dominated sequence) documented a temporary fall of the sea-level in the lowermost Aptian.

References Avram, E. & Melinte, M., 1998. Barremian-Aptian boundary in the Dimbovicioara area (Romanian Carpathians). Zbl. Geol. Palaeont. Teil 1, H. 11/12, 117-129. Patrulius, D. & Avram, E., 1976. Stratigraphie et corrČlation des terraines nČocomiens du Couloir de Dimbovicioara (Carpates Orientales). Comptes Rendues, 62/4, 135-160. Thomel, G., 1964. Les zones d'ammonites de l'Aptien des Basses Alpes. C. R. Acad. Sci. Paris, 258/17, 4308-4310.