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    Wyświetlanie 1-11 z 11
    Tytuł:
    Quaternary evolution of a Carpathian Foothills area: An example from the East Carpathians of Poland
    Autorzy:
    Zuchiewicz, W.
    Zasadni, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/191928.pdf
    Data publikacji:
    2010
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Quaternary sediments
    tectonic geomorphology
    neotectonic evolution
    Polska
    Opis:
    The East Carpathian Foothills of Poland witnessed two episodes of relief planation in the Pliocene, followed by formation of Early Pleistocene strath terraces preserved on flat-topped meander spurs in the San River valley at altitudes of 100-120 m above recent floodplains. In the following stages, intense erosion produced of a flight of strath terraces that are provisionally dated to the Narevian or Sanian-1 (Menapian or Elsterian-1; 75-80 m), Sanian-2 (Elsterian-2; 40-60 m), Odranian and Wartanian (Drenthe, Warthe; 20-30 m), and Vistulian (Weichse- lian; 8-16 m) times. During glacial stages, solifluction deposits mantled the feet of gentle slopes being coeval with fluvial deposition and accumulation of loesses and loess-like sediments on either side of the San River valley, particularly intense in the Weichselian. Interglacial warmings fostered downcutting of the pre-existing fluvial sediments as well as formation of fossil soils within loess sequences and deposition of peat in abandoned channels. In the Late Pleistocene and at the beginning of the Holocene, diversified tectonic movements took place leading to displacement of Weichselian and Holocene straths. During the Holocene, in turn, cut-and-fill terrace steps were shaped, organogenic sediments filled abandoned channels and oxbow lakes, and slopes became re-modelled by landslides and slopewash. The pattern of different types of relief, together with spatial distribution of topolineaments and some photolineaments in the eastern portion of the Polish Outer Carpathians, has been shaped due to mutual interactions between climatic, lithologic and tectonic factors. Well-pronounced topolineaments either follow fault-related zones of weakness, are associated with dense network of extensional cross-fold joints, or indicate recent reactiva-tion of some faults and/or joint sets.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2010, 80, No 3; 327-345
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Palaeogeography of the western Sandomierz Basin in Late Neogene and Early Quaternary times (Carpathian Foredeep, South Poland)
    Autorzy:
    Brud, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/191643.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Neogene
    Quaternary
    Early Pleistocene
    sub-Quaternary surface
    coarse-clastic fluvial sediments
    sub-Carpathian Furrow
    Sandomierz Basin
    Carpathian Foredeep
    Opis:
    The sub-Quaternary topography of the western Sandomierz Basin has been compared to variable thicknesses of Quaternary sediments and geomorphology of the area. The lithology and age of the top of Miocene strata have been determined. The Witów Series has been interpreted as a sequence of a braided river that used to flow into the retreating marine basin, forming a fan delta whose age, according to macrofloristic determinations, has been assigned to the Late Miocene. Lower Quaternary gravels cap the remnants of a planated surface situated at 240-250 m a.s.l. The Błonie gravel horizon occurring at a similar altitude was deposited by a river active in Narevian and/or Nidanian glacial stages, and its top underwent reworking during the Sanian-2 stage. Deposits infilling the fossil sub-Carpathian Furrow have been mapped and dated to the Cromerian s.l. interglacial stage. The final alluviation of this segment of the furrow took place during the Sanian-2 stage. Reconstruction of the drainage pattern during the Eopleistocene, South-Polish glaciations, and Masovian inter- glacial stage has been proposed as well.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2004, 74, No 1; 63-93
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Detection of near-surface geological heterogeneity at Starunia palaeontological site and vicinity (Carpathian region, Ukraine) based on microgravity survey
    Autorzy:
    Porzucek, S.
    Madej, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/191491.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    geophysics
    microgravity
    Quaternary sediments
    Starunia
    Carpathian region
    Ukraine
    Opis:
    Results of a microgravity survey performed in the abandoned Starunia ozokerite mine (Carpathian region, Ukraine), where in the early 20th century well preserved remains of large, extinct mammals were found, are discussed in the paper. A number of gravity anomalies indicating the geological heterogeneity at the sub-Quaternary strata have been observed. The assumed measurement observations also enabled the authors to interpret the results in view of density changes in the Quaternary strata. Most of the registered microanomalies coincide with the high-halite and ozokeritic Miocene salt-bearing Vorotyshcha beds. The distribution of the microanomalies reveals neither their correlation with the thickness of overburdens, nor any gravity impact of numerous abandoned wells. Gravity anomalies were mostly connected with the lithology of sediments and rocks obtained from geological boreholes drilled in the years 2007 and 2008, on the basis of which the anomalies' origin could be determined. A concentric, relatively negative gravity microanomaly of ca. 25 m in diameter was registered in the place, where very well preserved relics of the woolly rhinoceros had been found. They may be indicative of the existence of Pleistocene lakes (and/or palaeoswamps), into which the woolly rhinoceroses had sunk. Hence, an assumption can be made that the further search for successive zoological relics can be made in areas with similar anomalies under the low-density sub-Quaternary subcrop.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 365-374
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neofractures versus inherited fractures in structural analysis : A case study from Quaternary fluvial gravels (Outer Carpathians, Poland)
    Neospękania a spękania odziedziczone w analizie strukturalnej : przykład z czwartorzędowych żwirów rzecznych (Polskie Karpaty zewnętrzne)
    Autorzy:
    Tokarski, A. K.
    Świerczewska, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/191994.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    fractured clasts
    neotectonics
    Quaternary gravels
    Outer Carpathians
    Polska
    Opis:
    This paper presents the results of a detailed analysis of flysch-derived clasts within Quaternary fluvial gravels exposed close to a map-scale overthrust. These clasts are commonly fractured. For a given population of clasts, the number of fractured clasts is positively correlated with the clast size and negatively correlated with the grain size of clast-forming rocks. The fractures comprise both those inherited from earlier joints cutting source strata, and those formed in situ within the gravels (neofractures). These two groups of fractures show different diagnostic features. The inherited fractures are orientated at random in relation to geographic coordinates, where as the neofractures show a well-organized architecture. The inherited fractures are mostly inclined 80–90° to the a-b planes of the host clasts, whereas the neofractures are usually inclined at 0–80° to these planes. The occurrence of neofractured clasts within the analysed gravels results from tectonic activity post-dating gravel deposition.
    W czwartorzędowych żwirach rzecznych odsłoniętych w pobliżu regionalnego nasunięcia w polskich Karpatach Zachodnich powszechnie występują spękane klasty skał fliszowych. W analizowanym materiale klasty skał drobnoziarnistych są częściej spękane, niż klasty skał gruboziarnistych. Obserwuje się też dodatnią korelację pomiędzy liczbą spękanych klastów a ich wielkością. Wśród spękań występują spękania odziedziczone po spękaniach ciosowych tnących skały macierzyste oraz neospękania, które powstały in situ w żwirach. Te dwie grupy spękań cechuje różna orientacja w stosunku do współrzędnych geograficznych oraz do powierzchni a-b klastów, tj. płaszczyzny zawierającej oś o maksymalnym (a) i pośrednim (b) wymiarze. Spękania odziedziczone są zorientowane chaotycznie w stosunku do współrzędnych geograficznych, podczas gdy orientacja neospękań jest uporządkowana. Spękania odziedziczone są zorientowane niemal pionowo (80-90°) względem powierzchni a-b klastów macierzystych, natomiast neospękania są zorientowane pod katami 0-80° do tych powierzchni. Pochodzenie neospękań jest wynikiem aktywności tektonicznej, która miała miejsce po osadzeniu analizowanych żwirów.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2005, 75, 1; 95-104.
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Topography of the Magura floor thrust and morphotectonics of the Outer West Carpathians in Poland
    Autorzy:
    Zuchiewicz, W.
    Oszczypko, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/191413.pdf
    Data publikacji:
    2008
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    morphotectonics
    neotectonics
    Pliocene–Quaternary
    Magura thrust
    Outer Carpathians
    Polska
    Opis:
    Neotectonic (Pliocene-Quaternary) elevations and depressions detected on maps of subenvelope surfaces of the topography of the Outer West Carpathians of Poland are, to a certain extent, portrayed on the map showing topography of the Magura floor thrust, particularly in the western segment of the study area. The floor thrust of the Magura Nappe is highly uneven, its position changing from 725 m a.s.l. to more than 7,000 m b.s.l. The most prominent depression is located in the medial (S of Dunajec and Poprad confluence) segment of the Polish Outer Carpathians (2-7 km b.s.l.), and its axis trends NW-SE from the eastern margin of the Mszana Dolna tectonic window to the Poprad River valley. Another, much more shallower, Jordanów depression (2 km b.s.l.) is to be found NW of the Mszana Dolna tectonic window, shortly north of the Skawa River valley. Elevated structures, in turn, include the Mszana Dolna tectonic window, Sól-Skomielna (on the west), and Limanowa (on the east) elevations of subparallel orientation. Still farther to the east, a longitudinal elevation extending between the Klęczany-Pisarzowa and Świątkowa tectonic windows is to be seen some 10-15 km south of the Magura frontal thrust. South of this area, the Magura floor thrust slopes steeply down to more than 4 km b.s.l. A comparison between the pattern of elevated and subsided structures of the Magura floor thrust and subenvelope surfaces of different orders shows that in the western part of the Polish Outer Carpathians the highest-elevated neotectonic structures (in the southern portion of that area) coincide with depressions of the Magura thrust, whereas farther north a reverse pattern becomes dominant: neotectonic elevations coincide either with the Magura frontal thrust or with elevations of its surface. This is particularly true for an area comprised between 20° and 20°30’E meridians. The origin of such relationships is difficult to explain. We infer that one of possible factors could be Pliocene-Quaternary reactivation of faults cutting the Magura floor thrust, and particularly that one, which appears to separate the western-medial segment of the Outer Carpathians from their more eastern portion.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2008, 78, No 2; 135-149
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Upper Pleistocene and Holocene deposits at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)
    Autorzy:
    Sokołowski, T.
    Stachowicz-Rybka, R.
    Woronko, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/191556.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Quaternary fluvial sediments
    Velyky Lukavets River valley
    Starunia
    Carpathian region
    Ukraine
    Opis:
    An abandoned ozokerite mine (= Ropyshche), where large mammal remains were discovered in the first half of the 20th century, is located in the Velyky Lukavets River valley covered with Quaternary sediments. The catchment area includes a flysch sequence unconformably overlain by salt-bearing Lower Miocene molasses of the Vorotyshcha beds. Both the Upper Pleistocene and Holocene are represented by: channel (gravel, sandy gravel) and overbank alluvium (mud, peat, biogenic mud) and colluvium (mud, sandy mud) as well as by mine wastes. The channel sediments are usually found in the lowest fragments of the borehole logs and represent mainly material deposited in the straight segments of meandering river-beds. The most common, fine-grained (Mz = 61.33 to 7.11 ?m), distal floodplain sediments are locally up to 10 m thick and are dominated by massive mud lithofacies, which contain frequent burrows, root hairs or slightly larger root traces and reed rods. These sediments are characterized by rather stable grain size distribution, quite monotonous mineral composition, presence of resistant heavy minerals and quartz grains with traces of chemical weathering. Angular grains with conchoidal fractures and sharp edges also occur. Therefore, textural features show that the main sources of material were, most probably, weathering crusts of various ages developed on relatively poorly lithologically diversified Carpathian flysch strata and on Miocene deposits of the Carpathian Foredeep. With time, an increase of the content of material originating from mechanical weathering (frost action) occurred in the floodplain deposits, which can be linked to an increase of climate severity and reduction of vegetation. However, these changes are not recorded in the deposits, which developed mostly in closed hollows and accumulated mainly from suspension or from low-energy flows. This calm sedimentation was periodically interrupted by supply of more coarse-grained material (sand, gravel). A distinct predominance of overbank deposits in the sections documented by their thickness suggests that the northward flow of the Velyky Lukavets River was blocked as a result of either neotectonic movements or damming of the valley by landslide tongues. From the lithological point of view, the most favourable conditions for preservation of large, extinct mammals still exist in the two selected areas, where the total thickness of Pleistocene muds exceeds 2 metres. The first area is located in the vicinity of boreholes Nos 2, 3, 21, 22, 23, 28, 30 33 and 36N, and the other, smaller one, is placed around borehole No. 42.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 255-278
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geological control on the Osława River meander at Duszatyn, Western Bieszczady Mountains, Polish Outer Carpathians
    Autorzy:
    Margielewski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/191585.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    neotectonics
    structural control
    Quaternary alluvium
    Osława River
    Western Bieszczady Mountains
    Polish Outer Carpathians
    Opis:
    At Duszatyn village (Western Bieszczady Mts.), the Osława River forms an unique meander loop which is not typical for the mountainous area. Detailed analysis has shown that this landform was created due to the evolution of two left-hand tributaries of the Osława River during the formation of its regressive water-gap. These processes were determined by mass movements which have strongly stimulated the fluvial system. The origin of the Osława River meander was largely controlled by lithological differences in rock resistance, orientation of the joint pattern, as well as the presence of bordering oblique and thrust faults which have had a bearing on the diversified neotectonic uplift of the area.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2004, 74, No 3; 325-338
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of sub-Quaternary basement on the relief in the eastern part of the Pomeranian Lakeland, Poland
    Autorzy:
    Petelski, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/191668.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    relief of the top of sub-Quaternary deposits
    subglacial channels
    Kashubian Lakeland
    Gardno Lowland
    Polska
    Opis:
    Geological mapping works, conducted on 1:50,000 litho-petrographic map sheets of the South Baltic coast and the eastern part of the Pomerania Lakeland, show a clear relationship between large landforms of this area, like: subglacial channels, Wieżyca Hill, the ice lobe that accumulated Gardno moraine deposits, and sub-Quaternary relief. These landforms came into existence as a result of reactivation of pre-existing fault zones in the sub-Cainozoic basement, due to the ice mass loading during successive Pleistocene ice-sheet advances. Subglacial channels developed and thick tills and ice-dammed lake deposits were accumulated in the region. The subglacial channels and morainic belts are now dominating landforms in the Pomeranian Lakeland.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2011, 81, No 1; 105-114
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Lithology of glacial sediments of Sanian-2 (Elsterian-2) stage at Tenczynek Basin, Kraków region, Southern Poland
    Litologia osadów glacjalnych z piętra Sanu-2 w Kotlinie Tenczynka na zachód od Krakowa
    Autorzy:
    Rutkowski, Jacek
    Zuchiewicz, Witold
    Bluszcz, Andrzej
    Helios-Rybicka, Edeltrauda
    Powiązania:
    https://bibliotekanauki.pl/articles/27311296.pdf
    Data publikacji:
    1998
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    lithology
    petrography
    Sanian-2 glacial stage
    Elsterian-2 glacial stage
    Quaternary
    Tenczynek Basin
    southern Poland
    Opis:
    The paper deals with the lithology of Quaternary sediments that fill the Tenczynek Basin, Kraków Upland. The basin was eroded within Carboniferous strata before or during the Elsterian. The basin fill can be subdivided into three complexes, the middle one of which records a nearly complete glacial cycle, represented by glacier advance and standstill during the Elsterian-2 (Sanian-2) glacial stage. Sediments of the lower complex were deposited before or during that stage. Following this deposition, a terminoglacial lake was formed and became gradually filled with glaciolacustrine clays and silts that bear a few intercalations of diamictons, some of them shed by slumps. These sediments compose the middle, strongly disturbed complex which, in turn, is unconformably overlain by periglacial sands of the upper complex, deposited during a time-span comprised between the Sanian and Weichselian. The petrographic composition of gravels and cobbles, determined for a wide spectrum of grain-size classes, is highly variable due to differentiated exaration and the changeable supply of extraglacial material.
    Artykuł omawia litologię osadów czwartorzędowych wypełniających Kotlinę Tenczynka na zachód od Krakowa. Kotlina została wyerodowana w skałach karbonu przed lub w trakcie zlodowacenia Sanu-2. Piaski i żwiry dolnego kompleksu osadowego powstały przed zlodowaceniem i w wyniku zatamowania odpływu przez lądolód. Następnie doszło do utworzenia jeziora terminoglacjalnego i sedymentacji osadów glacilimnicznych, z wkładkami diamiktytów o bardzo zmiennym uziarnieniu. Osady te, budujące kompleks środkowy, są silnie zaburzone i przykryte niezgodnie przez peryglacjalne piaski pokrywowe kompleksu górnego, osadzone po zlodowaceniu Sanu. Skład petrograficzny żwirów i głazików w osadach glacjalnych, analizowany dla różnych przedziałów frakcyjnych, jest bardzo zmienny z uwagi na zróżnicowanie lokalnej egzaracji i zmiany w dostawie materiału ekstraglacjalnego.
    Źródło:
    Annales Societatis Geologorum Poloniae; 1998, 68, 4; 247--265
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular and isotopic compositions of gases adsorbed to near surface sediments at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)
    Autorzy:
    Dzieniewicz, M.
    Sechman, H.
    Kotarba, M. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/191497.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    near-surface geochemical survey
    adsorbed gases
    origin of gaseous hydrocarbons
    origin of carbon dioxide
    Quaternary sediments
    Starunia palaeontological site
    Carpathian region
    Ukraine
    Opis:
    The near-surface geochemical survey of gases desorbed from sediment samples was carried out in the area of an abandoned ozokerite mine in Starunia, where remnants of mammoth and three woolly rhinoceroses and one almost completely preserved rhinoceros carcass were discovered in 1907 and 1929. Numerous hydrocarbon seeps (gas and oil "eyes") occur on the surface of the study area. Analyses of molecular and stable carbon isotope compositions of adsorbed gases were carried out in two variants. The first included sampling of cuttings from 30 auger boreholes at depths of 4.8, 5.6 and 6.4 m. In total, 88 samples were collected. In the second variant core samples were collected from 17 selected boreholes. In total, 78 samples were taken from various depths to 12 m. The results of molecular composition analyses of desorbed gases indicated high saturation of near-surface sediments with the oil. The highest concentrations of alkanes were detected in Miocene strata. Hydrocarbon migration from deep accumulations to the surface was relatively fast and proceeded along the faults, fractures and cracks. In the near-surface zone hydrocarbons were subjected to oxidation and dehydrogenation, which resulted in generation of unsaturated hydrocarbons and hydrogen. These processes were most intensive in the Pleistocene sediments and in the mine dumps. Increased concentrations of hydrogen may also originate from water radiolysis in the presence of hydrocarbons. Concentrations of carbon dioxide in the adsorbed gases show the higher values in comparison with the analysed gaseous compounds. However, a slight increase in CO2 concentration was detected in the mine dump, which may indicate conditions more favourable for hydrocarbon oxidation. Carbon dioxide from the analysed adsorbed gases is of thermogenic origin. Occasionally, insignificant influence of secondary hydrocarbon oxidation and/or Quaternary organic matter can be observed. Concentrations of alkanes, alkenes and carbon dioxide in the gas derived from desorption of rock samples are lower and the concentration of hydrogen is higher than those measured in free gases. This indicates that additional effects from recent (e.g. microbial) processes are absent.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 421-437
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distribution and origin of gaseous hydrocarbons and carbon dioxide in the Quaternary sediments at Starunia palaeontological site and vicinity (Carpathian region, Ukraine)
    Autorzy:
    Kotarba, M. J.
    Sechman, H.
    Dzieniewicz, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/191503.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    near-surface geochemical survey
    depth gas distribution
    stable carbon isotopes
    gaseous hydrocarbon origin
    carbon dioxide origin
    Quaternary sediments
    woolly rhinoceros
    Starunia palaeontological site
    Ukrainian Carpathians
    Opis:
    Near-surface gases were investigated in Starunia, where remains of mammoth and woolly rhinoceroses were discovered at the beginning of the 20th century. Samples were collected at 30 measurement sites, from 0.8, 1.6, 2.4, 3.2 and 4.0 m depths and analysed for their molecular and isotopic compositions. Most of the methane and all higher gaseous hydrocarbons accumulated within the near-surface zone are of thermogenic origin. The distribution of thermogenic methane and higher gaseous hydrocarbons in Quaternary sediments is variable and, generally, increases with depth. Microbial methane or a mixture of microbial and thermogenic methane also occurs at the near-surface zone. The presence of hydrogen and alkenes in the near-surface gases also suggests a contribution from recent, microbial processes. Helium of crustal origin migrated through the Rinne Fault and other tectonic zones located in the study area, and was subsequently dispersed during migration through the lithologically diversified Pleistocene and Holocene sediments. The high variability of the carbon dioxide concentration and stable carbon isotope composition at various depths in the near-surface zone is caused by its polygenetic origin (thermogenic, microbial, and oxidation of hydrocarbons and Quaternary organic matter), and also by its dissolution in water and oil during migration through lithologically diversified Pleistocene and Holocene sediments. Zones of thermogenic methane occurrence within Pleistocene sediments, dominated by muds saturated with bitumen and brines, provide the most favourable environment for preservation of large extinct mammals. It is likely that during the Pleistocene winters, when thick ice and snow covered the tundra lake and swamp, zones of outflow of brines, oils, helium, and thermogenic gaseous hydrocarbons had a higher temperature, which could have resulted in melting and cracking of the ice cover and drowning of large mammals. The most favourable conditions for preservation of large, extinct mammals probably still exists in the vicinity of sampling probe sites Nos 21, 22, 23 and 36. Zones of dominance of microbial methane concentrations are less favourable sites for preservation of extinct mammals, because this methane was generated within recent swamps and also within recent descending meteoric waters which infiltrated into Pleistocene and Holocene sediments. Older Pleistocene microbial gases have already escaped to the atmosphere.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2009, 79, No 3; 403-419
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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