Cătălina CIORTESCU¹, Gabriel Ovidiu IANCU¹, Ryszard KRYZA² & Dumitru BULGARIU^1
1"Al. I. Cuza" University of Iaşi, Department of Geology, 20A Carol I Av., 700505 Iaşi, Romania, e-mail-catalina_ciortescu@yahoo.com
²University of Wrocław, Institute of Geological Sciences, ul. Cybulskiego 30, 50-205 Wrocław, Poland e-mail-ryszard.kryza@ing.uni.wroc.pl

MINERALOGY AND DISTRIBUTION OF THE DETRITAL HEAVY MINERALS IN THE BISTRIȚA AURIE AND DORNA RIVERS ALLUVIAL SEDIMENTS

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The Bistrița Aurie and Dorna rivers, tributaries of the longest Romanian mountain river Bistrița, located in the Eastern Carpathians, have been selected for investigations of heavy minerals in alluvial sediments. The investigations comprise basic parameters such as colour, morphology and grain size. However, the major aspect of this study concerns identification of heavy mineral species and their compositions and determining the frequency in the heavy mineral fraction in order to trace their sources and to indicate their possible economic significance. The sampling and method used was in situ panning. Heavy mineral assemblages of the Bistrița Aurie and Dorna rivers are mainly concentrated in grain-size fractions between 500 and 71 μm. The main heavy minerals in the alluvial sediments studied are: garnet (most abundant in the Bistrița Aurie sediments), pyroxene (abundant and present only in the Dorna sediments), manganese- and iron oxides, ilmenite, rutile and pyrite. Other minerals, such as zircon, monazite and titanite, have been identified only as inclusions in various types of minerals. The alluvial sediments of the Bistrița Aurie contain mineral species entirely specific of a metamorphic source, while the Dorna sediments contain minerals typical of both metamorphic and igneous sources.