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11.
The properties of carbonate rocks are often the result of multiple, diagenetic events that involve phases of cementation (porosity occlusion) and dissolution (porosity enhancement). This study tests the hypothesis that the order of these events is a major control on final porosity and permeability. A three-dimensional synthetic model of grainstone is used to quantify trends that show the effect of early cementation, non-fabric selective dissolution, and then a second-generation of (post-dissolution) cement. Models are 3 mm3 with a resolution of 10 μm. Six simple paragenetic sequences are modelled from an identical starting sediment (without accounting for compaction) where the same diagenetic events are placed in different sequences, allowing for quantification of relative changes in the resultant porosity and permeability for each diagenetic event, the trajectory through time, as well as for each final rock. All modelled paragenetic sequences result in reductions in porosity and permeability, but the order of diagenetic events controls the trajectory and final rock properties. Differences in the order of early cement precipitation alone produce variable final values, but all follow the porosity–permeability relationship as expressed by the Kozeny-Carman equation. However, final values for the sequences which include a phase of dissolution fall on a new curve, which departs from that predicted by the Kozeny-Carman relationship. This allows an alternative form of porosity–permeability relationship to be proposed: κ = 2280ϕ–30,400, where ϕ is porosity (%) and κ is permeability (mD). Hence while the Kozeny-Carman relationship predicts porosity–permeability changes that occur with cementation, it is unable to capture accurately changes within the pore network as a result of dissolution. Although the results may be dependent on the properties of the initial carbonate sediment and simplified diagenetic scenarios, it is suggested that this new porosity–permeability relationship may capture some generalized behaviour, which can be tested by modelling further sediment types and diagenetic scenarios. 相似文献
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Aleksandra Stachowska Maciej Łoziński Michał Śmigielski Anna Wysocka Leszek Jankowski Piotr Ziółkowski 《Sedimentology》2020,67(7):3783-3808
The anisotropy of magnetic susceptibility is a well-known geological proxy in revealing the directional tectonic and sedimentological features of rocks, although it can be ambiguous in situations where these two factors co-occur. This paper demonstrates the usefulness of the anisotropy of magnetic susceptibility in determining palaeotransport directions in turbiditic rocks that underwent subsequent thrusting and folding. This study demonstrates that the magnetic lineation is largely unsuitable as a palaeocurrent direction proxy, and suggests that the imbrication of magnetic foliation is better in such cases. Moreover, the anisotropy of magnetic susceptibility results were analyzed in reference to a joint and fold study within the framework of the regional structural geology. Magnetic fabric investigations were conducted in the eastern part of the Outer Western Carpathians (south-east Poland). During the study, a total of 191 oriented palaeomagnetic samples were collected from three outcrops (Nasiczne, Dwernik and Hoczew) in the Krosno Beds, Silesian Unit. For the purpose of sedimentological analysis, 121 m of turbidite successions were documented and 126 directional sedimentary structures were measured. The magnetic anisotropy of sandstones revealed typical sedimentary fabrics, often overprinted by variably intense tectonic deformation. Oblate susceptibility ellipsoids from Nasiczne showed tilt coherent with the palaeoflow direction, whereas the rocks from Dwernik and Hoczew contained triaxial magnetic fabric developed during compressional palaeostress. This paper suggests that medium-grained and coarse-grained sandstones, preferably with high mica content, are the most suitable for palaeotransport reconstructions among the studied lithologies. 相似文献
13.
Aleksandra ?AJNOVI? Nenad GRBA Franz NEUBAUER Milica KA?ANIN-GRUBIN Ksenija STOJANOVI? Nenad PETKOVI? Branimir JOVAN?I?EVI? 《《地质学报》英文版》2020,94(5):1591-1618
A combined inorganic and organic geochemical study was carried out on marls and mudstones collected from the Lower Miocene Lopare Basin, Bosnia and Herzegovina. A total of 46 samples collected from two boreholes, Pot 1 (depth of 193 m) and Pot 3 (depth of 344 m), showed that element abundances like boron (B), lithium (Li), strontium (Sr), uranium (U), chromium (Cr), nickel (Ni), magnesium (Mg), sodium (Na) and calcium (Ca) are much higher than average than in the upper continental crust (UCC). Chemical composition indicates at least two sources: (i) Mesozoic ophiolites occurring in the north of the investigated area, and (ii) dacito-andesitic pyroclastics (Mesozoic to Cenozoic). Lopare Basin sedimentation was influenced by strong evaporation resulting in a partly hypersaline lake, which formed during a warm climatic period, probably during the Miocene Climatic Optimum. A brief episode of humid climate conditions resulted in the basin filling-up and deposition of felsic sediments enriched in thorium (Th). Organic geochemistry shows that the majority of studied sediments contains predominantly immature to marginally mature algal organic matter (OM). The biomarker patterns are generally in agreement with the geological history of the Lopare Basin and inorganic and mineralogical data. Conversely, the molecular distribution of n-alkanes as reliable climatic and δ-MTTC as paleosalinity indicators do not support this conclusion. 相似文献
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Notti Davide Wrzesniak Aleksandra Dematteis Niccolò Lollino Piernicola Fazio Nunzio Luciano Zucca Francesco Giordan Daniele 《Landslides》2021,18(7):2341-2365
Landslides - In November 2016, an extreme rainfall event affected the Ligurian Alps (NW Italy). Consequently, several landslides and debris flows occurred in the upper Tanarello stream basin. In... 相似文献
16.
Krzysztof M. Markowicz Tymon Zieliński Sandra Blindheim Michael Gausa Anna K. Jagodnicka Aleksandra E. Kardas Wojciech Kumala Szymon P. Malinowski Tomasz Petelski Michał Posyniak Tadeusz Stacewicz 《Acta Geophysica》2012,60(5):1308-1337
This paper presents the measurements of a vertical structure of aerosol optical properties performed during the MACRON (Maritime Aerosol, Clouds and Radiation Observation in Norway) campaign, which took place in July and August 2007 at ALOMAR observatory on Andøya island (69.279°N, 16.009°E, elevation 380 m a.s.l.). The mean value of the aerosol optical thickness (AOT) at 500 nm during campaign was 0.12. Significant increase of the AOT above longtime mean value was observed on 7 and 8 August 2007 when the AOT exceeded 0.4 at 500 nm. Analyses of back trajectories show the aerosol transported from over Africa and Central Europe. The aerosol extinction coefficient obtained from the synergy of ceilometer and sun photometer observations reached 0.05–0.08 km?1 (at 1064 nm) in the dust layer. The single scattering albedo at the ALOMAR observatory decreased during the dust episode to 0.93–0.94, which indicates some absorptive aerosols in the lower PBL. 相似文献
17.
This article examines the implementation and impacts of a program intended to improve research-led teaching in schools. Little consideration is given to the role of research-led teaching in schools; the argument is that this is a consequence of fractures between schools and universities. A program was developed to bring contemporary geographical research of university scholars into schools. Examining this program, the finding is that being exposed to research: improves access to up-to-date knowledge; heightens student enthusiasm; and informs choices students make about their learning. This article calls for bridges to be built between universities and schools upon the nexus of teaching and research. 相似文献
18.
Apolinarska Karina Pleskot Krzysztof Pełechata Aleksandra Migdałek Michał Pełechaty Mariusz 《Journal of Paleolimnology》2021,66(1):41-53
Journal of Paleolimnology - We conducted year-round, monthly monitoring of the stable isotope composition of DIC and water in hypereutrophic Lake Kierskie, western Poland, along with isotope... 相似文献
19.
The presence of Cuon alpinus in Poland is documented here for the first time. Between 650 and 450 ka, Lycaon lycaonoides dominated the open lands, while Cuon alpinus priscus tended to prefer forests, mountains and highlands. Canis mosbachensis coexisted in all these environments. Between 480 and 430 ka, there was a drastic reduction in the number and range of L. lycaonoides. The balance between canids was disturbed and a critical point in the lycaon–wolf relationship was passed. Probably between 450 and 400 ka, the lycaon was too rare to be a real competitor and a limiting factor for the wolf. It was also at this time that the lycaon disappeared completely. With disappearance of the lycaon from Eurasia, there was a slow increase in the body size of the wolf. Between 400 and 300 ka, the dhole and the wolf were still close in body size, but the wolf was slowly increasing in size. Between 300 and 250 ka, the wolf became the dominant dog species and took a niche occupied until then by the lycaon. Because of competition, C. alpinus decreased in body size and adapted to hunting and living in forest, mountain and highland environments. 相似文献
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Aleksandra Samecka-Cymerman Grzegorz Kosior Krzysztof Kolon Bronisław Wojtuń Krzysztof Zawadzki Andrzej Rudecki Alexander J. Kempers 《Journal of Atmospheric Chemistry》2013,70(2):105-114
This research is continuation of the investigation of metal accumulation in native and transplanted moss Pleurozium schreberi in the most industrialized and affected region in Poland (Upper Silesia). We tested the hypotheses that in Upper Silesia transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent; a 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. An assay was carried out with native mosses at 27 polluted sites and mosses from an uncontaminated control site transplanted to the same 27 polluted sites. P. schreberi collected from the same sites as classified for more and less polluted basing on Pb and Zn concentrations show quite different pattern of pollution with mercury; The accumulation of Hg by the transplants increased much faster in the first 45 days of the experiment (accumulation factor 1.5–6.7; mean 3.4?±?0.5) in comparison with the second period from day 45 to 90 (accumulation factor 1.0–1.6; mean 1.2?±?0.1). The 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. Transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent. 相似文献