The Triassic in Southwest Bulgaria. New data on the Upper Triassic in the Konyava Mountain

Abstract

The sections East of the peak Golemiya vruh North of the village of Bounovo exhibit a deposition of the marine red beds of the Upper Triassic Komshtitsa Formation (Moesian Group) directly over the biodetritic limestones of the Ladinian Radomir Formation (Iskur Carbonate Group). The basal parts of the Komshtitsa Formation are proven with foraminifer fauna as Lower Carnian. Laterally the Lower Carnian red beds are replaced by the algal limestones of the Trun Formation (Iskur Carbonate Group). Farther North-West, in the Zemenska Mountain, the Trun Formation fills in the whole volume of the Carnian and the lower and middle parts of the Norian Stage, the Komshtitsa Formation being confined to the middle and upper parts of the Norian. These new data point at a diachronous evolution of the Late Triassic geodynamics and sedimentation, with local total lack of the upper carbonate platform and its lateral replacement by red bed sedimentation as early as in Early Carnian time.