Studia Quaternaria

Neotectonic studies in Poland concern mainly manifestations of those tectonic movements that have been active in Late Neogene and Quaternary times, as well as geodetically measured recent vertical and horizontal crustal motions. Among problems of particular interest, the following should be listed: periodicity of neotectonic (mostly Quaternary) activity, estimation of the parametres of the neotectonic stress field, amplitudes and rates of Quaternary and recent movements, development of neotectonic troughs and young faults, mutual relationships among photolineaments, geological structures and recent seismicity, as well as the role of tectonic reactivation of fault zones due to human activity. Neotectonic faults in Poland have developed in Neogene and Quaternary times due to reactivation of Laramian or older structures, or in the Quaternary due to reactivation of Neogene faults. The size of throw of Quaternary faults changes from 40-50 m and >100 m in the Sudetes and the Lublin Upland, to several - several tens of metres in the Carpathians. The average rate of faulting during Quaternary times has been 0.02 to 0.05 mm/yr, what enables one to include these structures into the domains of inactive or low-activity faults. A similar conclusion can be drawn from the results of repeated precise levellings and GPS campaigns. Strike-slip displacements have been postulated for some of these faults. Isolated faults in Central Poland have shown middle Quaternary thrusting of the order of 40-50 m, and some of the Outer Carpathian overthrusts tend to reveal young Quaternary activity, as indicated, i.a., by concentrations of fractured pebbles within the thrust zones. Episodes of increased intensity of faulting took place in the early Quaternary, in the Mazovian (Holsteinian) Interglacial, and during or shortly after the Odranian (Drenthe) glacial stage. Some of the faults have also been active in Holocene times. Recent seismic activity is often related to strike-slip faults, which in the Carpathians trend ENE-WSW and NE-SW, whereas outside the Carpathians they are oriented parallel to the margin of the East-European Platform and the Sudetic Marginal Fault. Future investigations should put more emphasis on palaeoseismotectonic phenomena and practical application of neotectonic research.

Neotectonic structures of the Upper Silesia that originated during the last 5 Ma (Pliocene and Quaternary) overlap Miocene grabens and horsts of the Carpathian Foredeep. They had been reactivated in Pliocene as an effect of the young Alpine uplift of the Carpathian Foredeep. It is postulated that ice-sheet derived compaction of a thick Miocene deposits was the most significant agent of the development of neotectonic depressions. Glacioisostasy of mobile bedrock structures was presumably also an important component of vertical movements. The amplitude of neotectonic movements is estimated to 40-100 m, basing on DEM map analysis, analysis of sub-Quaternary structural maps, and the Pleistocene cover thickness. The present-day tectonic phenomena are generated by mining-induced seismicity. These are connected with stress relaxation in the deep bedrock thrust zones of the Upper Silesian Coal Basin.

The paper aims at reconstructing Pleistocene slope processes and transformation of tectonic relief in two sections across the northern margin of the Krzeszowice Graben. The investigations are based on the analysis of deposits present on the slopes of fault-line scarps. The lithology and stratigraphy of these deposits was reconstructed based on analysis of outcrops and boreholes. Detailed lithological logs were prepared, along with grain size analyses, and determination of CaCO3, Fe2O3 and Corg contents in fine-grained sediments. The studied fault-line scarps were transformed by Pleistocene denudation. The type and intensity of these processes were different in the sections studied. In the Będkowice area, accumulation prevailed; the fault-line scarp became covered with sediments. In the Karniowice area, in turn, periglacial processes caused degradation of the fault-controlled slope. In the lower part of the fault-line scarp, the intensity of degradation processes was limited by repeated presence of sediment cover which preserved the substratum. Differences in the intensity and type of Pleistocene denudation can be explained by different heights of fault-line scarps, controlled by tectonic structure and neotectonic movements.

In this paper we describe a fossil graben and associated normal faults and joints. The graben occurs in the section of the Vistulian (Weichselian) and Holocene sediments in an archaeological excavation site at Brzezie, in the central part of the Polish Carpathian Foredeep (Wieliczka-Gdów Upland, western part of the Sandomierz Basin). Normal faults strike mostly NNE-SSW and dip steeply about 65 - 850. Some of them, namely master normal faults, bound the fossil graben. The joints form orthogonal pattern and are closely spaced close to the faults. They developed simultaneously with faulting. Normal faulting took place during the Vistulian - Mesoholocene (Neoholocene?) time, according to age of the archaeological artefacts which were found in the faulted sediments. The faulting was probably finished during the Neolithic or even later, during the Bronze Age. The NNE-striking normal faults connected with graben formation could have been produced by reactivation of a NE-striking sinistral regional fault in the basement.

This paper presents the results of a detailed analysis of fractured clasts hosted within Miocene and Pleistocene paraconglomerates that are exposed close to a map-scale overthrust. Both these paraconglomerates bear numerous fractured clasts (22-50%). The architecture of fractures (joints and minor faults) is well-organized and independent of both clast orientation and the degree of clast roundness. The fractures were formed in situ, most probably due to neotectonic activity of the map-scale overthrust. The number of fractured clasts is positively correlated with the clast size, and negatively correlated with the grain-size of clasts of detrital rocks. The number of fractured clasts increases in clasts of detrital rocks, compared to those of quartzites and magmatic rocks.

The aim of this paper is to present a multidisciplinary project dealing with analysis of young crustal movements in the Orava Basin, Polish Western Carpathians, on the basis of a three year long gravimetric, geodetic, geological and morphostructural study. The problem consists in quantitative interpretation of the obtained gravimetric results, i.e. in combining temporal gravity changes with those of geodynamic crustal processes. Gravity surveys conducted in 2004 and 2005 show a decrease in gravity values at benchmarks situated in the Central Carpathian Palaeogene Basin and Magura Nappe, while the central potion of the Orava Basin reveals the opposite trend. Such changes, if confirmed by successive measurement campaigns, appear to indicate recent uplift of the basin margins and subsidence of the basin itself.

One of the shortcomings of the analysis of subfossil Cladocera (water flee) remains is that preservation of remains is selective. Of Daphnia spp. which are very common in zooplankton assemblages of lakes, usually only postabdominal claws and ephippia are found. In the present paper I describe Daphnia shell margins and some tail spines from the Holocene sediments of a lake in southern Finland where the margins were much more abundant than the postabdominal claws, indicating that postabdominal claws may be underrepresented. Daphnia claws, shell margins and tail spines were found also in surface samples of 17 Finnish lakes and thus the abundance of tail spines could be compared with that of postabdominal claws. The results showed that in most cases the tail spines are more abundant than postabdominal claws and may give a closer estimate of the true abundance of Daphnia. However, in some lakes claws were clearly more frequent than tail spines. Apparently, there are differences in preservation of different types of Daphnia remains between lakes, possibly connected with water chemistry. Overall, the results indicate that probably Daphnia remains are always underrepresented in lake sediments.

Cladoceran remains preserve selectively in lake sediments. Possibly all Cladocera species leave at least some identifiable remains in lake sediments. Exosceletal body parts of families Chydoridae and Bosminidae preserve best but other families are only variably represented in sediments by their outer body parts. Identification of all possible remains helps to achieve more precise palaeolimnological reconstruction of past ecosystems by Cladocera analysis. This article describes, together with photograph and line drawing the subfossil post-abdomen and post-abdominal claw of Ceriodaphnia, previously not widely identified.

The present work is a part of the development of a method which uses the relative proportions of asexually and sexually reproducing chydorid females to reconstruct the length of the open-water season. Surface sediments (5 cm) of Lake Aitajärvi, northern Finnish Lapland, were examined for modern and recent proportions of chydorid cladoceran ephippia in subarctic climate near the pine limit. The total chydorid ephippium proportions (TCE) were steadily 9.5-9.7 % in the Aitajärvi sediment but declined to 8.4 % in the uppermost sample. The result was compared with the surface sediment TCE from four lakes in southern Finland where it varied between 3-6%. It was also compared with the TCE from two lakes in northernmost Finnish Lapland above the treeline in very severe climate, where it was 26-30 %. These very high values suggest that there might be a threshold in climate conditions between Aitajärvi and the two northernmost lakes that alters the reproduction of chydorids towards an even more important role of sexual reproduction.

Alona protzi is a rare species of Cladocera, occurring in lake littoral throughout Europe. However, little is known about this animal, and so far it has not been included in provisional lists of species found in Finland. In this short report we present our findings of Alona protzi, both recent and subfossil material, as well as one previous, unpublished finding site of the species in Finland. We found three subfossil shells of this species in the bottom sediments of two lakes. In a third lake we found intact animals, an ephippial female and a male, while sampling stony bottom of lake littoral.