Dumbrava alluvial fans (foothills of the Vršac mts., Banat)

Abstract

Morpho-litho-genetic unit Dumbrava represents the sediments of alluvial fan in the foothills of Vršac Mts. at 150-190 asl. These sediments were identified through direct field research and exploratory drilling on the southern slope of the Vršac Mountains foothills, near the right bank of the Mesić stream at the Dumbrava locality, and on the northern slope of the Vršac Mountains foothills in the Markovac village area at the Izvorei stream. The representative profile for this unit is the Dumbrava profile. The Dumbrava alluvial fan is primarily composed of sub-rounded quartz-feldspar gravels and sands with rare clay lenses. In the lower part of the profile, larger pebbles (up to 5 cm) are found in a fine gravel matrix. A weakly developed subhorizontal layering is observed, resulting from vertical grading of the material by size. The sediments of the Dumbrava alluvial fan lie over the sands of the upper pont, as observed in the Mesić stream valley profile and confirmed by deep drilling. Over the alluvial deposits lies a 6-8 meter thick deluvial debris cover. The general appearance of the deposits and their sedimentological characteristics most closely resemble the model of humid alluvial fans from the Lower and Middle Pleistocene, which form at the exits of narrow valleys located between high mountain relief and their significantly lower foothills.