In order to better constrain the hydrogeological conditions to the depth of 50 m in the area of water extraction for Wroclaw city, a multi-faceted geophysical survey has been applied. We have combined electrical resistivity tomography (ERT), ground penetrating radar (GPR) and magnetic resonance sounding (MRS) techniques. The results of geophysical investigations indicate the presence of three rock layers with different permeability. The first layer, up to 2 m below ground surface, represents a discontinuous horizon composed of impermeable rocks. The next one, a porous and permeable stratum (aquifer) with a thickness of approx. 5-10 m, comprises saturated sands and gravels. The observed aquifer is characterized by good hydrogeological parameters, wherein hydraulic conductivity (k) equals 5 X 10-4 m/s and porosity reaches 23%. The third layer, below 10 m, is composed of loamy impermeable sediments intercalated with moraine till. At greater depths (>20 m) they are still loamy rocks, but occurring with interbeds of sands (sandy loam). This is confirmed by the hydraulic conductivity in the order of 10-6 m/s, which is typicalfor semi-permeable rocks. Noteworthy, no additional aquifers have been observed to the depth of 50 m.
The risk of dangerous radon emissions in Estonia is high, being among the highest in Europe. In almost 33 per cent of Estonian land area, the content of radon in soil-contained air exceeds the safe limit for unrestricted construction (50 kBq/m3). In such high radon-risk areas the concentration of radon in soil-contained air ranges from 50 to 400 kBq/m3, in a few cases reaching up to 2,100 kBq/m3 exceeding the permitted level for residential areas. The situation is particularly serious in the northernmost part of the country, where uranium-rich graptolite argillite (Dictyonema shale) and the Obolus phosphorite are close to ground surface and their particles are constituent parts of Quaternary deposits. Radon emissions from bedrock have been investigated in detail, but to date Quaternary strata as a source of radon emissions are poorly studied. According to our measurements the highest concentrations of radon are related to tills containing clasts and fines of graptolite argillite and phosphorite. Glacial deposits include also granitoidal material, containing U, Th and K, which have been transported by glaciers from the outcrop areas of crystalline basement rocks in Finland and the Gulf of Finland. Due to weathering, outwash and repeated redeposition other genetic types are poorer in radioactive elements and they are weaker sources of radon.
The investigated area is located in the middle section of the Warta River valley, where the Neogen deposits with lignite series occur within the Adamów tectonic graben. In the Kozmin-North excavation, opened for extraction in 2008 and belonging to the "Adamów"Lignite Mine, the Neogene deposits are covered with an about 30-m thick Quaternary series. The research was carried out to identify the origin and age of the Quaternary sediments. As a result, four sandy series and three till series were identified, which were deposited during the South Polish Glaciations and Middle Polish Glaciations. North Polish Glaciations sediments developed in extraglacial conditions.
Eighteen samples of Quaternary unconsolidated sediments from the Piotrków Plateau and the Radomsko Hills in central Poland have been analysed for their average grain size, sorting, skewness and kurtosis. The analysis was carried out by seven computational methods of interpolation and nine extrapolation methods. It appears that linear interpolation, the traditional method (DOS), and the Josek and Gradistat Programs give comparable results, but that quadratic interpolation and the method of moments should not be applied since they yield unreliable results. The method of moments gives unduly high or unduly low parameter values because of the application of different, i.e. incomparable measures in the applied formulae. It should be stressed that only extrapolation provides, if performed under the right conditions, the possibility to determine some parameters, in particular skewness values.
Several possibilities to present and to interpret the results of granulometric analyses of Quaternary fluvial, aeolian, glacial and wash-out slope deposits were investigated. Attention is paid particularly to the cumulative curves at a probability scale and the frequency curves, and it is shown how these curves can help to determine the sedimentary environment. The inclination of the cumulative curves in the part of the maximum proportion of a particular grain size appears significant. It appears possible to obtain information on the density and dynamics of the transporting medium from the course of the cumulative curves (inclination and spread of grain size). The examination of textural parameters allows to draw regression lines characteristic of both deposits from various sedimentary environments and deposits from one single environment but with different histories as to their transport dynamics.
The Ground Penetrating Radar (GPR) measurements presented in this paper had two main objectives. The first was to analize the possibility of using GPR method in examination of sediments in a mountainous geological environment and the second objective was to assess the special distribution of post-glacial sediments and their thickness at a selected site. The experimental measurements were carried out on in the alp of Ornak in the western part of Tatra Mountains This article provides a brief theoretical analysis of possible use of the georadar method in post-glacial sediment examination. The results of GPR surveys done in the reflection profiling mode enable the distinction of zones with different amount of till, clay, sand, gravel and rock debris in the post-glacial sediments.
PL
Badania GPR prezentowane w artykule miały dwa cele: pierwszym było określenie możliwości zastosowania metody GPR do badania utworów osadowych w górskich warunkach geologicznych, a drugim - określenie przestrzennego rozkładu i miąższości utworów postglacjalnych w wybranym miejscu w górach. Badania eksperymentalne przeprowadzono na hali Ornak we wschodniej części Tatr. W artykule zamieszczono krótką dyskusję teoretyczną na temat możliwości zastosowania metody georadarowej do badania osadów postglacjalnych. Zaprezentowane w artykule wyniki badań GPR wykonanych w technice refleksyjnej pozwoliły na wyróżnienie w osadach postglacjalnych stref z różnym nagromadzeniem glin, piasków, żwirów oraz odłamków skalnych.
7
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
W pracy zaprezentowano skład przezroczystych minerałów ciężkich znajdujących się w czwartorzędowych osadach spoistych (gliny zwałowe, mułki, lessy) oraz osadach sypkich (fluwioglacjalnych, rzecznych, wydmowych). Podano propozycję wykorzystania tła spektrum mineralnego mogącego stanowić poziom odniesienia w trakcie prowadzenia szczegółowych badań problemowych.
EN
The paper is focused on the composition of transparent heavy minerals in both cohesive (glacial tills, muds and loesses) and non-cohesive (glaciofluvial, riverine and dune in origin) Quaternary deposits. The proposal is given how to use the background of mineral spectrum that can be a reference level while carrying out detailed problem research.
8
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The profile of the borehole Podgórze B1, which at first was reconed among the Mazovian Interglacial was revealed by palynological analyses to represent the Ferdynandów Interglacial. Additional paleozoological studies confirmed presence of diverse faunal remains: Ostracoda, Pisces, Mollusca and Coleoptera, which allow to better recognize the character of environment of the interglacial sediments in Podgórze.
9
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Strefa współcześnie lewoprzesuwczego uskoku Dien Bien Phu (DBP), o orientacji NNE-SSW do N-S, jest jest jednym z najbardziej aktywnych uskoków sejsmotektonicznych w Indochinach. W NW Wietnamie uskok ten, 160 km długości i 6-10 km szerokości, przecina skały osadowe i metamorficzne wieku późnoproterozoicznego, paleozoicznego i mezozoicznego, a także paleozoiczne i górnotriasowe granitoidy. Wzdłuż DBP występuje 5 niewielkich basenów typu pull-apart (od północy: Pa Tan, Chan Nua, Lai Chau, Muong Pon oraz Dien Bien Phu), spośród których przeanalizowano szczegółowo dwa największe, tj. Lai Chau i Dien Bien Phu. Oba baseny są obramowane przez uskoki lewoprzesuwcze i lewoprzesuwczo-normalne, wywołujące ugięcie i przemieszczenie sieci drenażu, obecność licznych grzbietów zagradzających (shutter ridges), jak również zuskokowanie tarasów i stożków napływowych. Na obecność normalnej składowej ruchu uskokowego wskazują: trójkątne lica progów uskokowych, wysoko wzniesione tarasy skalno-osadowe w przełomowych odcinkach dolin, zawieszone doliny oraz wysokie i niewyrównane spadki koryt rzecznych. Minimalne rozmiary przemieszczeń lewoprzesuwczych wynoszą od 6-8 m do 20-50 m dla dolin holoceńskich oraz 2-2,5 km dla dolin środkowo-późnoplejstoceńskich w różnych segmentach uskoku. Miąższość osadów czwartorzędowych zmienia się od kilku--, kilkunastu metrów w Lai Chau do blisko 130 m w basenie Dien Bien Phu. W basenie Lai Chau osady tarasu średniego (23 m) rzeki Nam Na (stanowisko most Muong Te) zostały wydatowane techniką OSL-SAR na 26-45 ka. Osady te zostały przecięte uskokiem normalnym o zrzucie ok. 12 m w ciągu ostatnich 13 tys. lat i przykryte przez gliny stokowe, 8-12 m grubości, z kilkoma poziomami klinów koluwialnych z poziomami ostrokrawędzistego gruzu, a utworzonymi przypuszczalnie dzięki epizodom palesejsmicznym po dacie 13 ka. Kontakt między utworami stokowymi a piaskowcami i mułowcami triasu również ma charakter uskoku normalnego. W basenie Dien Bien Phu aluwia tarasów wczesno-środkowoholoceńskich zostały wydatowane OSL-SAR na 6,5-7 ka, podczas gdy najmłodsze pokrywy aluwialne zostały zdeponowane 1,8-2,7 ka oraz niemal współcześnie. Aluwia górnoplejstoceńskich stożków napływowych na wschodnim obramowaniu basenu są pocięte serią spękań oraz drobnych uskoków o orientacji zbieżnej z orientacją strefy DBP (N20oE). Przemieszczone tarasy i stożki napływowe pozwalają sądzić, iż minimalne tempo ruchu lewoprzesuwczego wynosiło 0,6-2 mm/rok w holocenie oraz 2-4 mm/rok w środkowym i późnym plejstocenie. Natomiast tempo holoceńskich ruchów wypiętrzających zmieniało się od 1 mm rocznie w rejonie Lai Chau do 0,4-0,6 mm/rok na zachód od Dien Bien Phu. Długoterminowe, średnie prędkości czwartorzędowych ruchów podnoszących są trudne do oszacowania; przekraczały one jednak wartość 0,05 mm/rok.
EN
The Dien Bien Phu (DBP) fault zone, oriented NNE to N, is one of the most seismically active fault zones in Indochina. In NW Vietnam, this zone is 160 km long and 6-10 km wide, cutting through sedimentary and metamorphic rocks of the Late Proterozoic, Palaeozoic and Mesozoic age, as well as Palaeozoic and Upper Triassic granitoids. Along the DBP fault zone there occur relatively small, narrow pull-apart basins (from the north: Pa Tan, Chan-Nua, Lai Chau, Muong Pon, and Dien Bien Phu), the two largest of which (Lai Chau and Dien Bien Phu) have been studied in detail. Both are bounded by sinistral and sinistral-normal faults, responsible for offset and deflected drainage, presence of numerous shutter ridges and displaced terraces, and alluvial fans. The normal component of motion is testified to by well-preserved triangular facets on fault scarps, highly elevated straths in river watergaps, overhanging tributary valleys, as well as high and uneven river-bed gradients. Our observations indicate a minimum recent sinistral offset ranging from 6-8 m to 20-50 m for Holocene valleys to 2-2.5 km for middle-late Pleistocene valleys in different fault segments. The thickness of Quaternary sediments varies from a few to a dozen or so metres in Lai Chau to a few tens or even 130 m in DBP basin. In the Lai Chau basin, the middle terrace (23 m) alluvia of Nam Na River at Muong Te bridge, shortly north of the confluence with Song Da, have been OSL-SAR (optically-stimulated luminescence; single aliquot regenerative dose technique) dated to 26-45 ka. These sediments were normal-faulted by some 12 m after 13 ka, and mantled by vari-coloured slope loams, 8-12 m thick, containing colluvial wedges composed of angular debris. These wedges were probably formed due to at least two palafoseismic events postdating 14-13 ka. The contact between slope sediments and Triassic bedrock is along a normal fault (N10°W, 78E), accompanied by 0.3-0.35-m-wide fault gouge. In the Dien Bien Phu basin, in turn, alluvium of the upper Holocene terrace has been OSL-SAR dated to 6.5-7 ka, whereas the younger terrace sediments give ages of 1.8-2.7 ka. Displaced terraces and alluvial fans allow us to suppose that the sinistral and sinistral-normal faults bounding narrow pull-apart basins in the southern portion of the DBP fault reveal minimum rates of left-lateral strike-slip ranging from 0.6 to 2 mm/yr in Holocene and 2-4 mm/yr in middle-late Pleistocene times, whereas rates of Holocene uplift tend to attain 1 mm/yr north of Lai Chau and 0.4-0.6 mm/yr west of Dien Bien Phu. Long-term, average Quaternary uplift rates are difficult to estimate, the minimum values certainly exceeding 0.05 mm/yr.
10
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Pasmo Smoleńsko-Niegowonickie składa się z szeregu wzgórz wapiennych, częściowo przykrytych osadami czwartorzędowymi. Na podstawie szczegółowego kartowania geologicznego oraz wyników analiz granulometrycznych i mineralogicznych, wydzielono i opisano sześć typów osadów czwartorzędowych: gliny zwietrzelinowe, piaski fluwioglacjalne, piaski eoliczne, lessy, osady jeziorne, osady rzeczne. Ponadto opracowano genezę i stratygrafię osadów wypełniających, znajdującą się w centralnej części badanego terenu, jaskinię Biśnik, która jest stanowiskiem paleolitycznym. W jaskini wyróżniono trzy serie osadów akumulowane w czasie zlodowaceń południowopolskich, zlodowaceń środkowopolskich, zlodowacenia Wisły, a także w holocenie. Wydzielone typy genetyczne osadów czwartorzędowych skorelowano z osadami jaskiniowymi. Uzyskane wyniki badań i przeprowadzona korelacja posłużyły do rekonstrukcji morfogenezy tego terenu.
EN
The Smoleń-Niegowonice Range is a chain of limestone hills party covered with Quaternary deposits. On the basis of detailed geological fieldwork, study of the Biśnik cave filling and numerous grain-size and heavy mineral analyses, the stratigraphy of the Quaternary sediments and relief evolution were elaborated. The relief comprises forms of erosional-denudational origin e.g: inselbergs, valleys, gorges (Fig. 2) controlled by tectonic structure and limestone lithology of the bedrock, and purely accumulation forms such as weathering covers, glacifluvial covers, alluvial surfaces, loess covers and dunes. The Quaternary deposits consist of weathering loams, glacifluvial sands, lacustrine sands and silts, loess, dune sands, fluvial sands and silts (Figs. 3 & 4). The origin and stratigraphy of sediments filling the Biśnik cave - an important palaeolithic site were investigated (Mirosław-Grabowska, 1995; Mirosław-Grabowska et al., 1995; Cyrek, 1994). The 5 m thick section of the cave sediments consists of three main series composed of 18 layers identifiable on the basis of geological, archaeological and palaeontological data (Fig. 5). Below the basal series, autochthonous residual clays of terra rossa-type (layer 18) occur. They originated in the Tertiary, probably in the Pliocene. Series I is composed mainly of loams with limestone rubble. Layers 17-14 accumulated during the South and Middle Polish Glaciations. Layers 13-12 are correlated with the Eemian Interglacial. Layers 11-8 accumulated during the Vistulian Glaciation. The overlying series II consist of three layers (7-5) of fluvial sands. Fluvial accumulation in the cave is the result of its low morphological position in the slope of adjacent valley. Series III comprises loess and eolian sands (layers 4-2) accumulated during the Upper Plenivistulian. The uppermost part of the section consist of Holocene humus (layers 1a, 1b). The distinguished genetic types of the Quaternary deposits were correlated with the cave sediments (Fig. 4). The correlation helps to establish the stratigraphy of the Quaternary deposits in the studied area. During the Tertiary this area was exposed to intense chemical weathering and, then, to denu- dational and erosional processes. The limestone inselbergs, valleys and gorges were formed. Weathering loams and residual clays were accumulated at that time (Różycki, 1972). During the South Polish Glaciation, only layers 17-16 in the cave were probably deposited. During the Middle Polish Glaciation the glacifluvial sands were accumulated (Bednarek et al., 1978; Szczypek, 1984) and layers 15-14 in the cave. The Eemian Interglacial is represented only by two loam layers in the cave with strongly weathered limestone debris. During the Vistulian Glaciation this area was exposed to fluvial and eolian processes (Szczypek, 1984). The lacustrine silts, loess covers and dunes were formed (Bednarek et al., 1978). During the Holocene, the alluvial flood-plains and small dunes (Dulias, 1997) were formed and soil processes developed. At present, denudational and erosional processes mainly in the loess covers are observed.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.