Scholarly record

HEAVY MINERAL ABUNDANCE AND DISTRIBUTION IN FLUVIAL DEPOSITS OF THE SAINT GEORGE BRANCH, DANUBE DELTA, ROMANIA

Iulian Pojar, Cătălin Gheablău, Laura Tiron Duţu, Andrei Briceag, Florin Duțu

Abstract

Heavy mineral concentrations formed in fluvial deposits present the signature of the mineral provenance and of the hydraulic sorting during transport and accumulation. The sedimentary discharge of the Danube River has been preferentially deposited due to the mineral physico-chemical properties, such as size, morphology and density, as well as local hydrodynamic factors. Besides these natural aspects, the recent modifications of the Danube and its deltaic branches are associated with a significant remodelling of the distribution of terrigenous minerals, especially the heavy mineral ones. This paper is focussed on the mineralogical study of the terrigenous material identified in the Saint George branch of the Danube Delta. Based on the observed mineral morphology and abundance, we propose herein a model of the sediment provenance, including also their features linked to the preferential sorting that mirror local hydrodynamic conditions. One main assemblage of the heavy fraction have been identified: garnet + kyanite + hornblende + epidote. Analysing crystal contributions and morphology for each assemblage, we have pointed out the source areas that are mainly the Southern Carpathians and the Eastern Carpathians. The Northern Dobrogea Orogen and Moesian, Scythian and Moldavian platforms are considered subordinated source areas. The identified assemblage bring evidence from the presence of medium to high grade metamorphic rocks. Another minor source is composed of igneous rocks and various sedimentary rocks, which include turbidites.

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