ARHIVELE OLTENIEI - Universitatea din Craiova

THE GENETIC CONTROL FACTORS OF THE LIGNITE TYPESFROM WESTERN OLTENIASANDU BOENGIUThe territory located South of the Southern Carpathians and West of theJiu up to the Danube, includes, from the geological point of view, two majorstructural units: the Carpathian Foredeep (Getic Depression) and the WallachianPlatform (part of the Moesic Platform situated between the Southern Carpathiansand the Danube).The formation of the coal from western Oltenia was conditioned bymany factors; the quantitative and qualitative features of the lignite types fromwestern Oltenia depended on the paleogeographical factor, tectonic factor,climatic factor, biotic factor, and on the coal-like facieses factor. Besides thegenetic control exerted by these factors, the persistency time of certain specificconditions played a determinant role.a) The tectonic factorWithin the Dacic Basin, there developed two structural-genetic types ofcoal-generating areas: the Carpathian Foredeep, where the coal-like complexesdisplay a great development, and the Moesic Platform, where the coalaccumulations are poorer (Fig.1). Thus, we can talk about a Pliocene coalbearingbasin only within the molasses-like filling from the foredeep, whichpresents a maximum development along its inner side; here, there are locatedabout 22 coal beds more than 2 m thick.The coal accumulations from the cover of the platform belong to thecategory of anthracophores, which always has a reduced number of beds (2-3)that are more than 2 m thick and cover small surfaces; within the area of theCarpathian Foredeep, it can be noticed a close correlation between the greatestthickness of the most important coal beds and the areas where Motru coal-likecomplex reaches thicknesses oscillating between 80 and 140 m.The tectonic factor that qualitatively controls the coal genesis is thedifferential subsidence, while from the qualitative point of view the hydrologicalregime of the marsh determines the type of coal generating vegetation.The accumulation of the filling up deposits in the inner flank of theforedeep corresponds to the Rhodonian-Wallachian tectogenetic stage. Thevertical tectonic movements represent the main cause of the regularity of thesedimentary deposits, especially of the coal deposits. The research emphasizedthe oscillating-rhythmic character of the vertical movements from Motru – Jiuarea; thus, it was possible to separate more sedimentation stages. A completestage is made up of a lignite bed and the rocks from its top. It was established, asARHIVELE OLTENIEI, Serie nouă, nr. 21, 2007, p. 365–372