ARHIVELE OLTENIEI - Universitatea din Craiova

366Sandu Boengiua condition necessary for the formation of a peat bed, that its speed of increasehas to be equal to the sinking speed; thus, the lignite deposits from the DacicBasin could develop 1 .Fig. 1. – Cross section through Pliocene deposits with coal west of the Jiu river 2 :1) predominantly clayish deposits; 2) sand strata and intercalations; 3) lower Dacian (Getian) sandydeposits; 4) predominantly Pontian marl deposits; 5) Quaternary deposits; 6) faults; 7) exploring leads.In the evolution of the Pliocene coal-bearing field from Oltenia, theresucceeded many main stages that include the fluvial, fluvial-lacustrine,telematic, and lacustrine phases, when the main coal bed formed. The secondcause of regularity is represented by the fluvial divagation mechanism, whichled to the formation of some thin coal bed in incomplete stages.Subsidence was quite active within the entire Oltenia and very uneven asduration, especially if we take into account that this territory is located on twodistinct major tectonic units, which had their own independent movements ofoscillation.Within the Pliocene deposits from Oltenia, there can be distinguished:coal deposits overlapped to the platform, which comprise relatively thin coallikecomplexes and with a low number of coal beds; coal deposits overlapped tothe foredeep, which are the thickest and the most numerous, due to a long periodof stagnation / slow sinking and to a repeated instability.b) The paleogeographical factorFrom the paleogeographical point of view, there can be noticed twotypes of coal sedimentation basins, paralic and limnic.1 C. Enache, L. Pănoiu, L’escauisse tectonique des dépôts à lignites de la régioncomprise entre le Jiu et Danube, dans ,,Studia Universitatis Babeş-Bolyai”, SérieGéographie, 1989, p. 29; S. Pauliuc şi al., Le rôle des fracteurs tectoniques et paléogéographiquesdans la genèse de la formation lignitifére de Jiu-Motru entre les vallées de Motru et de Jiltz,„Annales de l’Université du Bucarest”, 1988, p. 28.2 S. Boengiu, C. Enache, The evolution of the pliocen-cuaternary paleofora in theMotru basin, „Forum Geografic”, no.1., Craiova, Universitaria Publishing House, 2002, p. 69-75.