SEDIMENTOLOGY AND SOURCE AREA COMPOSITION FOR THE NEOPROTEROZOIC-EOCAMBRIAN TURBIDITES FROM EAST MOESIA

Abstract

The basement of the Moesian Platform is extremely heterogeneous, including rocks ascribed to the Archean, Palaeoproterozoic and Neoproterozoic. Largely concealed by the Palaeozoic to Cenozoic platform cover, the basement exposed in the tectonic block of Central Dobrogea contains mainly Neoproterozoic-Eocambrian turbidites (the Histria Formation), deformed under very low grade metamorphic conditions at the end of the Neoproterozoic, in the Cadomian or Baikalian events. The Histria Formation includes channelized, midfan turbidites and distal, outer fan turbidites, forming two sandstone dominated, upward coarsening and thickening sequences, separated by a much thinner, upward fi ning and thinning sequence. Sedimentological, mineralogical and petrological studies are consistent with the model that the turbiditic basin was sourced by a continental margin dominated by an active volcanic arc. From various lines of evidence, a foreland basin as the tectonic setting for the turbiditic sedimentation is favoured, although a forearc origin was also proposed. The paper presents an overview of the main sedimentological, mineralogical and petrographical data on the turbidites, and discusses the palaeogeographic and geodynamic signifi cance of the succession in a wider context of the southern margin of the East European Craton.