ARHIVELE OLTENIEI - Universitatea din Craiova

The genetic control factors of the lignite types from western Oltenia 369During the depositing of the Dacian coals, the climate displayed meanannual temperatures higher than nowadays, with small differences betweensummer and winter; so, it was a warm-temperate climate with a humidityfavourable to the development of subtropical elements.The subsequent modifications of the thermal and hydric factors led to amore continental climate, which is well-reflected in the flora remains 7 .The palynological research made at the level of the VIII lignite bed fromLupoaia-Motru open pit proved that the warming of the climate during the LowerRomanian is supported by the increase of the quantity of intermediary (Abies,carva, Pterocarya, Yelcova, Tilia etc.) and thermophilic elements (Arecipites,Monocolpopollenites, Myrica, Recvesia, Symplocos etc.). The artic-tertiaryelements (Picea, Tsuga, carpinus, Ulmus etc.) continued to be well represented.On the bases of the diversity of the thermophilic and intermediaryelements it can be proven that there occurred a warming of the climate ascompared to the Lower Dacian, but the precipitation amount was lower than theone registered during the Lower Dacian.The warm and moist temperate climate, which favoured thedevelopment of vegetation in the proximity of the sedimentation basin, presentedmean temperatures of 13 – 14°C and about 1,000 – 1,100 mm annual rainfall.An original reconstitution of the marshy paleoenvironment from theLower Romanian from Lupoaia – Motru can be found in the PalaeontologyMuseum of Babeş – Bolyai University in Cluj-Napoca.d) The biotic factorThe vegetal communities represented a main controlling factor of thepeat features and the features of the resulting coal initially depended on thequantity and on the quality of the vegetal material. The influence of thephytologic factor upon the petrographic composition of the lignite from Olteniawas well emphasized by the research that separated 5 paleophytocoenosesinstalled in 5 paleobiotopes: the marginal area → the forest with Sequoia; theseasonally flooded area → the marsh with sedge alternating with deciduousforests; the area almost permanently flooded → the marsh with Gliptostrobus;the permanently flooded area (0 – 2 m) → the marsh with Phragmites; thepermanently flooded area (2 – 3 m) → the marsh with aquatic plants.Even if it is macroscopically and palynologically documented, theresearchers consider that the forest with Sequoia abienta developed at random andthere are only a few trees, which are not significant as coal-generating material.The participation of different taxons in the paleophytocoenoses is thefollowing one: 32% Gliptostrobus europaeus and Gliptrotroboxylon; 10%Phragmites oeningensis; 14% Byttneriophyllum; 10 % Salix; 8% Monocotyladiv. sp.; 8% aquatic plants; 4% Typha.7 St. Roman, Observations concernant les palynomorphes, Cronotratigraphie undneostratotipen, Bucureşti, Editions de l’Académie Roumaine, 1995, p. 72.