The Cao Bang Basin is the northernmost of the basins related to the Cao Bang-Tien Yen Fault Zone in northern Vietnam. The basin is filled with a thick series of continental deposits. However, the exact age of the sedimentary basin infill has been under discussion for a long time. Because of new published data, the authors have decided to revisit this basin. Palynological data has allowed us to assign the Cao Bang Basin infill to the Lower Oligocene PC1 complex of the Shangcun Fm. (southern China). Among the saccate grains of gymnosperms, the domination of Cathaya and Pinus was observed, whereas angiosperms are represented by Carya, Celtis, Hammamelidaceae, Ulmus and also Pterocarya, Quercus, the Castanea–Castanopsis–Lithocarpus group, and the Loranthaceae. Among pteridophytes occur Laevigatosporites, Osmundaceae, and Pteris. The sedimentological features of the Cao Bang Basin are distinct from those of other basins from the Cao Bang-Tien Yen Fault Zone. The basin is filled with a wide variety of clastic deposits, from some of coarse-grained, alluvial-fan origin, through sandy beds of fluvial origin up to fine, organic-rich lacustrine deposits. The coarse-grained lithofacies are built of clasts derived mainly from local sources. The sandstones from the basin equally are submature or immature. They contain a lot of lithoclasts, the composition of which depends on the sample location within the basin. The potential source area is composed of older sedimentary units and of granitic rocks. The geochemical samples studied reflect the geochemical composition of silicic source rocks with only a minor contribution of basic components. The succession that fills the basin is interpreted as a typical fill for relatively long-lasting evolving half-graben or strike-slip basins. Moreover, the basin is partly occupied by a subsequent present-day sedimentary basin of Quaternary age.
The Badenian Salinity Crisis took place at the early/late Badenian boundary and resulted in massive chemical sedimentation in the central Paratethys. The evaporating basin of the northern Carpathian Foredeep left behind gypsum and halite deposits tens of meters thick. As a very good medium for preservation, these evaporites are a fine source of diversified terrestrial palynomorphs. Plant communities reconstructed on the basis of both palynological analysis of sediments from the Bochnia and Wieliczka salt mines, as well as previously published studies from different localities within the evaporite basin, reveal the presence of wetland and mesic environments along the coasts of the northern part of the central Paratethys during the evaporative event. Among the most important taxa are Engelhardia, Ericaceae, Fagus, Liquidambar, Quercus, Taxodium/Glyptostrobus, Tricolporopollenites pseudocingulum, and Ulmus. The most characteristic feature of the palynofloras studied is the large amount (up to even 50%) of Ericaceae pollen in the spectra. Taxa representing a warm-temperate climate predominate in the palynofloras examined; however, representatives of a tropical/subtropical climate (i.a. Mastixiaceae) are also present. The presence of plant communities associated with wetland areas shows that the climate remained humid.
A 90 m-thick brown coal seam, the result of organic matter deposition in a fault-trough, is exploited in an open cast mine at Lubstów (Central Poland). Palynological analysis was conducted in order to determine which plants were the source of or ganic matter forming such a thick coal bed. The pollen spectrum is dominated by the gymnosperm pollen Inaperturopollenites, produced by trees closely related to the extant genera Taxodium and Glyptostrobus, the dominant constituents of swamp forests in SE North America and SE Asia today. However, the lack of xylites and preserved tissues in the coal does not support the conception of a swamp forest as the peat-producing community. There is also a significant percent age of angiosperm pollen in the coal, mainly from the groups: Castaneoideapollis, Tricolporopollenites exactus and T. pseudocingulum. The plants producing these pollen were probably the main constituent of the peat-producing community. The community shows signs of a shrub swamp with local tree islands and a low water table. Evidence for this also includes the de trital type of coal, the lack of preserved plant tissues and the presence of fungal remains. These character is tics show the existence of aerobic zones at the time of peat production. The peat was probably derived from angiosperms. Dome-shaped forms in the up per part of the de posit are the re mains of tree is lands. As de tri tus ac cu mu la tion is very rapid on the sur faces of pres ent-day tree is lands, a sim i lar rate of de po si tion may have taken place dur ing peat pro duc tion at Lubstów. This, com bined with sub si dence in the fault-trough, ex plains the great thick ness of the coal bed.
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