A palynological analysis was carried out on about 115 samples from two borehole cores, containing the infills of two palaeosinkholes at Górażdże. In both sinkholes, well preserved palynofloras were found in several lignite samples. A total of 54 fossil species, including 5 species of cryptogam spores, 7 species of gymnosperm pollen and 42 species of angiosperm pollen, were identified. No marine palynomorphs or microremains re-deposited from older sediments have been found in these samples. The spore-pollen assemblage made it possible to date the sinkhole deposits. The composition of the assemblage (e.g., abundance of small tricolporate pollen grains of the Fagaceae family, including Cupuliferoipollenites pusillus, Fususpollenites fusus, and Quercoidites microhenricii) indicates that the age of the lignites in both sinkholes is early Oligocene. Thus, the deposits at Górażdże correspond to the 5th Czempiń lignite seam group. The 5th seam occurs mainly in northwestern Poland and its lignites were deposited in isolated wetland basins with marine influences. The terrestrial Górażdże palynoflora without any marine influence shows mainly local early Oligocene vegetation from the surrounding area. The results are also direct evidence of the multiphase palaeokarst of the Silesian-Cracow Upland, including the deposition of lignites of various ages.
The upper Olenekian-Middle Triassic succession of the Tatricum domain (Central Western Carpathians, southern Poland) includes a few horizons of breccias, which are intercalated with early-diagenetic dolostones. On the basis of macroscopic and microscopic (including cathodoluminescence) observations, the paper presents a new interpretation of the genesis of the breccias and their diagenetic history. The rocks studied range from monomictic, cemented mosaic packbreccias to chaotic, unsorted, monomictic, particulate rubble floatbreccias. The processes that preceded the formation of the breccias encompassed the precipitation of evaporites and the early-diagenetic dolomitization of lime muds. The solution-collapse breccias were formed during episodes of cyclic sediment emersions in the upper Olenekian and Middle Triassic, as the result of gradual sediment collapse after karstic dissolution of the intercalated evaporites. After the brecciation process, during diagenesis the rocks were subjected to cementation by sulphate minerals and next, to multi-stage dolomitization. Later tectonic processes led to fracturing and even re-brecciation of the previously formed solution-collapse breccias.
The Zoloushka Cave belongs to a group of the largest gypsum caves in Western Ukraine (Bukovina region), developed in the middle Miocene (upper Badenian) evaporite series (Tyras Formation) on the SW periphery of the East European Platform. It is developed in the lower part of the evaporite series composed of gypsum, which is covered by a carbonate layer (Ratyn Limestone). The uneven upper surface of the gypsum at the contact with the limestone, the frequent occurrence of palaeokarst forms, and the presence of karstified fissures filled with allochthonous material indicate a sedimentation break between the gypsum and the overlying limestone. To support this thesis and to add new data on the age and palaeoenvironmental conditions of palaeokarst formation in the Bukovina region, palynological studies were carried out on material from the Zoloushka Cave. Palynofacies, sporomorphs and dinoflagellate cysts were studied. In total, over 70 sporomorph taxa and over 25 dinoflagellate cyst taxa have been identified in four samples collected from the filling of the palaeokarstic forms in the cave. The results of the analysis of sporomorphs and dinoflagellate cysts point to the formation of the palaeokarst during the sedimentation break that took place at the end of the late Badenian evaporitic cycle in the Western Ukraine region. The subsequent marine transgression led to the filling of the karst forms in gypsum with chemogenic carbonate material, precipitated from marine water (draperies) and with fine-grained, clastic material (pockets and fissures).
A sinkhole, developed in Middle Triassic limestones and filled with clastic and organic deposits, including lignite, was studied, in terms of its origin and age. The sinkhole represents a solution sinkhole, which originated through the subsidence of surficial deposits into an underlying cave system. The study permitted the recognition of three main stages of sinkhole evolution. During the initial stage, subterranean and surface karstification proceeded concurrently. As a result, a terra rossa cover developed at the surface and a cavern system was formed in the underlying bedrocks. During the second phase, both systems became connected and the soil cover subsided. This, in turn, involved the formation of a depression at the land surface and ponding of the drainage water. The pond was filled with plant debris, later giving rise to lignite formation. During the third and final stage, the sinkhole was filled with quartz sands with kaolinite, derived from eroded, Upper Cretaceous sandstones and marls. Results of pollen analysis from the sinkhole indicate the presence of mesophytic forests and show a significant role of riparian forests and herbaceous vegetation. The occurrence of abundant, freshwater algae and the pollen of aquatic plants evidences sedimentation of the infill in a water body (pond). The apparent dominance of arctotertiary and cosmopolitan, palaeofloristical elements, as well as the occurrence of only sparse, palaeotropical elements (mainly subtropical), indicate a warm-temperate climate (cooler than during the Early and Middle Miocene period). A comparison of the sporomorph association from the sinkhole with those from other Neogene sites provides evidence of its Late Miocene age (Late Pannonian–Early Pontian).
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Distinctly diverse results of TL dating are obtained for the deposits with similar lithofacial features but filling morphologically differentiated karst palaeoforms (dolines, pipes, pockets). The infillings of dolines and pipes are mostly of the Saalian age. Based on sedimentological analysis, their formation conditions are related to sub- or/and terminoglacial environment. The age obtained for all infillings of pockets is underestimated in comparison with lithostratigraphic data. A close genetic relationship between these forms and periglacial conditions seems to indicate that the reduction of TL signal is mostly influenced by the disintegration of grains resulted from the repeated freezing and thawing of glaciogenic deposits. A considerable influence of frost weathering on the decrease of thermoluminescence intensity of mineral grains is indirectly confirmed by the results of experimental investigations consisting in the repeated TL measurements of pockets’ infillings after successive freeze-thaw cycles.
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