DACIAN BASIN - GeoEcoMar

2.3. Was the Dacian Basin a lake or a sea ?
Dacian Basin location and delimitation. As previously discussed in this book
(Chapters 2.1.5 and 2.1.6), according to the existing paleogeographic data (Saulea
et al., 1969), the Dacian Basin displayed characters of an open water basin during
the Middle and Late Sarmatian (s. l.) time (Fig. 2.6). While functioning as a Middle
and Late Sarmatian (s. l.) open basin, the Dacian Basin was in wide direct contact
with the Euxinian Basin, exchanging water both northward and southward of the
Dobrogean dry land.
Surrounded on three sides by the Carpathians and Moesia, and with the Dobrogean
island/peninsula to the east, the Dacian Basin was a semi-enclosed basin (Fig.
2.8) during the Maeotian to Early Dacian. The basin was not completely landlocked
because it maintained a permanent connection with the Euxinian Basin and also
had episodic connections with the Pannonian Basin (Figs. 2.7 and 2.8).
Salinity of the Dacian Basin water body. As a consequence of isolation and internal
division into distinct sub-basins, brackish conditions established throughout
the Paratethys realm, starting from the Badenian (Rögl, 1999). Following the evolution
of the Paratethys domain, the Dacian Basin was brackish since it has been
formed. Based on the fauna in the western part of the Dacian Basin (the Valea Morii
profile), Marinescu (1978) concludes that the Sarmatian water had a salinity of 16 –
18 ‰. Pană (1966) and Saulea (in Saulea et al., 1969) reached similar results in the
northern part of the Dacian Basin. Papaianopol (in Papaianopol et al., 1995) indicates
that the Sarmatian fauna from the central part of the basin (Buleta, Râmnicu
Vâlcea area) suggest water salinity of approximately 14 ‰.
Papaianopol et al. (1995) point out the oscillating character of the water salinity
during the Maeotian time. A low salinity level (5 – 10 ‰, Marinescu, 1978) is
recorded in the lowermost interval, rich in Congeria fossils. The upper part of the
Early Maeotian (Oltenian), with Dosinia fauna, represents a high salinity episode
(approximately 18 ‰, Marinescu, 1978). Brackish, but mostly fresh-water fauna occur
in the Late Maeotian (Moldavian) deposits.
During the Pontian, the Dacian Basin water salinity was 7 – 8‰ (the level of
Congeria rhomboidea of the Bengeşti fauna) (Papaianopol et al., 1995). The salinity
value dropped to 5 – 6 ‰ and occasionally reached nearly 3 ‰ during the deltaic
Early Dacian.
The general picture portrayed by the data presented above is that the Dacian
Basin water salinity evolved from a high-brackish value (18 ‰) at the beginning of
the basin history to fresh-water at the terminal stage of the Dacian Basin existence
(since Middle Dacian time). The salinity values decreased and oscillated during the
Maeotian and continued to decrease during the Pontian.
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