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This article focuses on the petrographic analysis of chert samples from the Lower Danube Valley, Romania, between West of Olt Valley and East of Mostiştea Valley (Upper Palaeolithic sites and modern quarries in gravels of Frăteşti Formation and Danube terrace deposits). Macroscopic examination of hand specimens established visual characteristics of cherts and allowed the primary separation of samples. Microfacies analysis was carried on 116 thin sections, with special attention to grain categories, recognition of systematic fossil groups, matrix, and cement types, estimated by use of visual comparison charts for each thin section. Bulk dominant mineralogical phases were determined through X-ray diffraction on 82 samples. Microfacies analysis provided the means to characterize and classify cherts from the Lower Danube Valley (22 chert microfacies), demonstrating that raw-materials were previously inadequately characterized and defined too generally. Also, this study confirmed older hypotheses about local alluvial deposits as supply sources for some of the Upper Palaeolithic sites. [ABSTRACT FROM AUTHOR] more...

Continental deposits especially conglomerates have always been a challenge to geologists because of the lack of fauna and of the petrographic diversity of their particles. The continental deposits located in the south - western part of the Transylvanian Basin make no exception. This paper presents the sedimentological and facial features of the Şard Formation, which is cropping out on the right bank of the Ampoi River. Among the various sedimentary formations exposed in this region, the Upper Cretaceous to Lower Tertiary successions are of special interest, marking the sedimentary environment's evolution near the Cretaceous - Tertiary boundary. At this level a reddish continental formation was deposited and its formation is typical for alluvial depositional system (braided rivers). Detailed lithological columns have been logged recording textural parameters like pebbles morphometry and granulometry as well as the sedimentary structures and clast composition, over the 60 m thickness of the outcropping section [ABSTRACT FROM AUTHOR] more...