Mihai CONOVICI¹, Ioan POVARĂ², Iancu ORĂŞEANU³ & Constantin MARIN^2
1Geological Society of Romania, Nicolae Bălcescu 1, 010041, Bucharest, Romania, mihaiconovici@gmail.com
²"Emil Racoviţă" Institute of Speleology, Frumoasă 31, 010986, Bucharest, Romania, ipov.iser@gmail.com
³Romanian Association of Hydrogeologists, Traian Vuia 6, 020956, Bucharest, Romania, ianora@hotmail.com

GEOLOGICAL AND HYDROGEOLOGICAL FEATURES OF CERNA VALLEY (ARŞASCA-IUTA AREA, SW ROMANIA)

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Cerna Valley is a distinct tectonic sector of the Southern Carpathians, where the Late Cretaceous collision generated a large nappe stacking and a frontal accretionary prism dominated by mélange formations of olistostrome or tectonosome type, with a deformed, black argillaceous matrix, which contains many limestone blocks. Locally, we found fragments of piggy-back sedimentary basins; the deposits were previously described as the Arjana molasse formation. Gravitational collapse and slip due to the fluids pressure are the most important processes of the Late Cretaceous tectonic phase. Late extensional tectonics of transpressional-transtenssional type (the strike-slip tectonics) and the uplift of the crustal blocks on normal faults have created an asymmetrical half-graben structure with many secondary Riedel faults and characteristic secondary folds (flower structures). The very complex structures and morphology have created an intricate system of channels, less karstified, in which the groundwater flow is slow (6.66-20.8 m/h). The flower structures can be involved in the groundwater flow; these features favor the high flow rates of the Pişetori Springs. The water chemical composition is calcium-bicarbonate, Ca²⁺and HCO₃^– being the predominant ions.