DACIAN BASIN - GeoEcoMar

1.4. Dacian Basin structural framework
The outstanding morphologic variability of the Unionids fauna (25 genera and
112 species), the very large biomass of some of them and the massive shells of the
most Unionids suggest a habitat and an ecologic environment rich in carbonates
and nutrients, which generate both hyperthelic processes and an early reproduction.
This means a neothenic development associated with isolation and a parathenogenetic
reproduction.
The influence of the Euxinian Basin water was periodic during the Late Dacian
and is recognized in the fauna from the eastern part of the Dacian Basin. A second
Euxinian incursion, which occurred in the Middle Romanian time, reached the
western part of the Dacian Basin (the Lupoaia and Jilţ coal quarries). The ostracods
fauna is of Caspian origin (Cypris mandelstami, Eucypris famosa, Zonocypris membranae,
together with some endemic Cypris sp., Cyclocypris sp. and more Candonae).
Pană et al. (2004) also evidenced the presence of gastropods with the same
provenance (Caspia and Baicalia species).
The boundary between the Romanian and Pleistocene stage is marked by the
occurrence of the species Limnocythere jiriceki, followed by Ilyocypris caspiensis, Ilyocypris
angulata angulata and Trajanocypris laevis (in succession).
1.4. DACIAN BASIN STRUCTURAL FRAMEwORk 1
The orogens and the platforms situated in their foreland are the main geotectonic
features of the Romanian territory. Săndulescu (1984) (Fig. 1.7) distinguishes two
orogenic areas which evolved throughout the Mesozoic and Tertiary (the Carpathian
Orogen and the North Dobrogean Orogen) and a Cadomian Orogen (Central
Dobrogean Green Schists). The eastern European Platform and the Moldavian
Platform are older; the Precambrian foreland units and the Scythian and Moesian
platforms are younger, Paleozoic in age. The foredeep and the intra-Carpathian depressions
are the youngest structural units.
Two oceanic basins evolved in the Carpathian area during the Mesozoic period
of extension: the Transylvanides (or East Vardar) and the outer Dacides trough (or
Ceahlău-Severin) (e.g., Săndulescu, 1988; Schmid et al., 2008). The closure of the
two oceanic basins began in the Cretaceous and concluded with a continental
collision (Sarmatian, 10-11 Ma) recorded in the so-called Carpathians embayment,
which is the eastward prolongation of the Ceahlău-Severin ocean (e.g., Bala, 1987,
Ustasewski et al., 2008). Outer Carpathians or Moldavides (sensu Săndulescu, 1984)
(Fig. 1.7) represent a complex nappe pile, emplaced over the slightly deformed
foreland during the Miocene deformations (20–11 Ma, Săndulescu, 1984; Maţenco
and Bertotti, 2000).
1 Revised and amended by Liviu Maţenco
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