New data on the stratigraphy of the Tethyan Triassic in the Strandzha Mts., SE Bulgaria

Abstract

Data newly obtained by the authors together with already published evidence allow for a new analysis of the Triassic stratigraphy in the Strandzha Mountains. The Triassic in the Strandzha Mountains is referred with certainty to the Tethyan type of evolution. Its zonal stratigraphy is being detailized on the basis of conodont fauna, and the section is reconstructed and correlated with the other sections in Bulgaria. The numerous lithostratigraphic units already introduced have been created mainly due to secondary features as different degree of metamorphism and of tectonic reworking. They are now generalized into four formal units (Formations), and namely (from bottom to top): the basal Stravnitsa Formation built up of metagravelites, metapsammites and interbedded fine-pebble conglomerates; the Zaberska Formation (with two members, Gramatikovo and Kaziyskidol Members, respectively), built up of flyschoid alternation of shales, phyllites, metasiltstones, metapsammites, and marmorized limestones as well as of basic volcanics and ore bodies, within the age range from upper parts of the Spathian to lowermost parts of the Aegean Substage of the Anisian Stage; Kondolovo Formation built up of limestones and marmorized limestones, with Anisian (Pelsonian and Illyrian Substages) and Ladinian (Fassanian and lower and middle parts of the Longobardian Substage) age; and (at the top) the Lipacka Formation built up of flyschoid interbedding of limestones, slates and sandstones within the range upper parts of the Ladinian (Upper Longobardian Substage) – Norian (Lacian and parts of the Alaunian Substage).