DACIAN BASIN - GeoEcoMar

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Chapter 12. From Brackish-Marine to Continental-Fluvial Depositional Environment
FIGURE 12.1. Paratethys component sedimentary basins during the Dacian Basin existence.
Simplified and modified after Khondkarian et al. (in Popov et al., 2004)
12.2. SEDIMENTARY RELATIONSHIPS BETwEEN THE DACIAN
BASIN AND THE EUxINIAN BASIN
12.2.1. Facies at the boundary between Dacian and Euxinian Basins
The Dacian Basin sedimentary history includes two distinct development periods.
During the first one, the brackish-marine stage, which extends from the appearance
of the Dacian Basin (Middle-Upper Sarmatian s.l.; approximately 11 Ma) until it
dried out (starting with Middle Dacian time; approximately 4.5 Ma).
A comparison of the facies features of the Dacian Basin and the adjoining Black
Sea shelf is important for the knowledge of the sedimentary relationships between
the Dacian and the Euxinian basins (Jipa, 2008). The investigation focused on the
critical area of the limits between the Dacian and Euxinian basins. This area, situated
northward of the Dobrogean High and the contact between the north-eastern
part of the Dacian Basin trough and the western Black Sea Depression shelf, is
known as the Galaţi seaway (Saulea et al., 1969).
During the Late Miocene (approximately 11 to 4.5 Ma) both Dacian and Euxinian
basins represented brackish-marine water bodies, with common fauna, suggesting
faunal interchanges. At their contact area the two basins were morphologically
very different. The Dacian Basin appeared as a shallow but subsiding sedimentary
trough, which received a high amount of Carpathian-derived sediment, and accumulated
it with a high sedimentation rate. At the contact with the Dacian Basin, the
Euxinian western shelf was characterized by reduced detrital accumulation, with
its dominance of shell fragments and very fine-grained clastics. The lithofacies and
sedimentation rate differentiation between the Dacian and the western Euxinian
areas persisted during the Late Miocene time.