Marisia - Maros Megyei Múzeum Évkönyve 32/1. (2012)
Paleontology and mineralogy
Main Pliocene coal-generating phytocoenoses in Danube—Motru Area (Romania) Conclusions The main Pliocene coal-generating phytocoenoses in Danube-Motru sector were dominated by one of these taxa: Glyptostrobus europaeus, Byttneriophyllum tiliaefolium, Phragmites oeningensis, Salix rsp., Pandanus ssp. or by two, rarely three of them together. In these phytocoenoses Carya denticulata, Platanus platanifolia, Acer tricuspidatum, Carpinus betulus, Typha latissima, Liquidambar europaeum etc. were secondary elements. Depending on each phytocoenose and vegetal association recorded in the coal seams I— IV from the Danube-Motru sector, the next coal facies may be outlined: • The Forest with Sequoia, the swamps with Carex div. sp and Pandanus, replaced in time of the swamp with Salix and Myrica; • The swamps with deciduous hydrophytes with tow variants (with Salix div. sp. and Liquidambar europaeum, Acer tricusp idatum, Alnus sp., Carya aquatica, Juglans barbui etc., or with B. tiliaefolium)', • The swampy forests with Glyptostrobus associated or not with Taxodium dubium and/or Nyssa sp.; • The assemblages with Phragmites and Pandanus, with or without Typha latissima, Sparganium etc. • The vegetal assemblages with monocoenoses dominated by taxa: Stratiotes dacicus, Nymphaea, Ceratophyllum, Nelumbo, etc. Each of these facies generated different lithotype of coals. The dominance of the xylite and coal xylitic lithotype shows low values of the pH during the accumulation the parental vegetal material for the layer I and for the layer IV dominated the neutral environments to slightly alkaline that characterize swamps with Carex, especially the ones with Phragmites. The dominant anaerobic environment of the coal-generating swamps that has accumulated the parental vegetal material of the layer 1 allowed the preservation of wood fossil, fact noted in the macro-petrographic profiles where the xylite mostly predominates. The parental vegetal material of the coal seam IV accumulated under anaerobic conditions, or less aerobe ones, evidence being the large amount of the coal originating from the detritic facies in swamps with Phragmites and less with xylitic coal with origins in the facies coal of the forest with Glyptostrobus. Acknowledgements Acknowledge to Prof. Univ. Dr. Vlad Codrea for reviewing the translation of this paper and for the suggestions which have contributed it finish. 179
