Contributions to the knowledge of Quaternary formations in the southwest Romanian Plain

The processing of geological information obtained from some 1055 wells drilled in the southwestern Romanian Plain over an area of about 5200 km(2) has led to a better understanding of the structure and stratigraphy of Quaternary formations. The bending of the Danube River southwestwards and then westwards, between the Iron Gate Gorge and Brza Palanka, as well as the unbraiding at Ostrovul Corbului (Batoti) and 20 km farther downstream, at Ostrovu Mare (Gogosu), are the result of major trans-extensional movements of compartments buried west of the Timok fault, broken mainly from south to north due to the compression of the Southwestern Carpathians at the contact with the Moesian Platform. The morphostratigraphy of the Lower Member of the Danube Formation alluvia (Lower Pleistocene) deposited by the Danube and its tributaries on the High Fields of the Romanian Plain (250-110 m altitude) and of the Upper Member of the Danube Formation alluvia, of Middle Pleistocenee-Holocene age (170-20 m elevation, with 5-8 layers of terrace alluvia and a present-day floodplain) is partially elucidated. This is due to the existence of active earthquake-affected faults, involving unequal movements of alluvial layers. The 5-8 stepped fluvial terraces and floodplain relief is blanketed by the Aeolian Formation (up to 35 m thick in the High Plains and between 20 and 25 m-thick over the old terraces). Zoning the alluvial thickness of the Upper Member of the Danube Formation, omnipresent in the Lower Danube Valley, reveals the dominance (69.3%) of the 5-10 m and 10-15 m ranges. Terrace and floodplain alluvia are 15-20 m, 20-25 m and 25-30 m-thick on about 20.5% of the studied area: (i) near Miroc Tableland, on the subsiding sectors divided by faults (ii) stacked alluvial sequences) and (iii) at the confluence of the Blahnita and the Drincea rivers with the Danube Valley (3 stacked alluvial sequences). (C) 2014 Elsevier Ltd and INQUA. All rights reserved.