Depositional systems for the sedimentary deposits from the Lighidia perimeter, Bozovici, Caras-Severin county

In this paper it’s about the mineralogical composition of the sedimentary rocks in the Miocene of the Bozovici basin. The perimeter studied is between the Lighidia valley and Agriș valley. The Bozovici basin formed during the lifting and subsidence movements of the Neozoic basement in the Southern Carpathians. The studied deposits are represented by different types of claystones, sandstones, conglomerates, carbonate nodules and coal (lignite). Data on the mineralogical and petrographic composition of the rocks in the perimeter studied were determined by facies analysis, optical microscopy and X-rays diffraction. The identified minerals and lithoclasts are represented by quartz, feldspar, micas, carbonates, metamorphic and sedimentary lithoclast in sandstones and conglomerates, and clay minerals from the smectite group (montmorillonite) and kaolinite group in claystones. The highest concentration in montmorillonite was identified in tonstein (bentonite). The mineralogical data of tonstein suggests a felsic composition of initial volcanic material that has been transformed in conditions of a negative redox potential and an acidic pH of the swamps during Badenian. The X-rays diffraction was done in the laboratory of Oil-Gas University of Ploiesti. This method was used to characterize minerals from 8 samples collected from the Lighidia quarry. The results of the facies analysis, optical microscopy and X-rays diffraction provide us the evidence of the continental environments that correspond to an alluvial fan and overbank environments that evolves in a warm and humid climate.