National Repository of Grey Literature 23 records found  1 - 10nextend  jump to record: Search took 0.02 seconds. 
Correlation of abiotic proxies in Holocene lacustrine sediments of Peri-Atlantic Arctic
Roman, Matěj ; Nývlt, Daniel (advisor) ; Sedláček, Jan (referee)
The peri-Atlantic Arctic, one of the most sensitive components of the Earth climate system, experienced pronounced climatic fluctuations during the Holocene. Several external forcings were considered responsible for these variations, including decline of insolation on the Northern Hemisphere, changes in distribution of land ice mass, explosive volcanism, or changes in atmospheric and oceanic circulation. In order to explore the driving mechanisms of the peri-Atlantic Arctic environmental variability, three sites located in different parts of the region were selected for palaeoenvironmental reconstructions with focus on extracting the climatic information. With this intention, sedimentary cores from i) Lake Garmaksla, Central Svalbard, ii) Jarfjorden, northeastern Norway, and iii) Kobbefjord area, southwestern Greenland, were retrieved and subjected to multi-proxy investigation. The absolute chronostratigraphic framework was established by comprehensive radiocarbon (14 C) and short-lived radioisotopes (210 Pb, 137 Cs) dating. Further analyses include measurements of magnetic susceptibility, grain size distribution, element composition by means of X-ray fluorescence (XRF), and elements bound to organic matter, i.e. organic carbon, nitrogen, sulphur and biogenic silica. The relationships between the...
Upper Pleistocene environmental dynamics in central Europe: multidisciplinary research of loess/paleosols sequences and lacustrine sediments
Hošek, Jan ; Lisá, Lenka (advisor) ; Nývlt, Daniel (referee) ; Ložek, Vojen (referee)
The principal goal of this thesis was to provide relevant information on the spatiotemporal dynamics of erosion-sedimentation and weathering processes in the last climatic cycle and to interpret the obtained data in the context of European paleoenvironmental development. Representative sequences of loess, paleosols and lacustrine sediments from the area of the Bohemian Massif, the Carpathian Foredeep, the the Vienna Basin and the northern edge of the Panno-nian Basin were investigated using a wide range of instru-mental tools and paleontological methods. A uniform analytical approach applied to these sedimentary facies has provided ample new information about the paleoclimatolog-ical and paleoenvironmental development of East-Central Europe - an important region in the transition zone from oceanic to continental macro-climatic settings. The individu-al studies included in this PhD thesis cover the complete period of the Upper Pleistocene (MIS 5-2; ~130-12.7 ky BP) and are presented as separate chapters in the order of the superposition of strata. Chapters III/1-3 deal with the results of research into six loess/paleosol sequences (LPSs) situated in the Central Bohemian Massif, throughout the Moravian Valleys, and at the northwest and north edge of the Pannonian Basin. A detailed paleoenvironmental...
Recent development of Ferdinandbreen valley glacier in Petuniabukta (Svalbard)
Tomíček, Jiří ; Engel, Zbyněk (advisor) ; Nývlt, Daniel (referee)
Svalbard archipelago is located halfway between the Northern coast of Norway and the North Pole. About 60 % of Svalbard area is covered by glaciers of many types, from small cirque to large ice caps. Retreat of most glaciers in Svalbard has been recorded since the Little Ice Age at the end of the 19th century. Deglaciation of Svalbard landscape is connected with significant changes of natural environment, such as changes of erosion and acumulation processes, climate change or beginning of vegetation succession. This thesis aims to establish the elementary glaciological parameters of valley glacier Ferdinandbreen located in Petuniabukta, central part of Spitsbergen, by analyzing remote sensing data and field GPR and (d)GPS survey and evaluate it's evolution between 1960 - 2014. Glacier's length and area have been based on aerial imagery of years 1960, 1990, 2009 and GPS measurements in 2014. Ice thickness and volume have been derived from GPR measurements. The length of the glacier in 2014 was 1,401 km, area 0,560 km2 and volume 6 561 684 m3 . The maximum measured ice thickness in 2014 was 42,5 m. During the period 1960 - 2014, the length of the glacier had been reduced by 45 % and area by 69 %, ice thickness had been reduced by 23,5 m during the period 1990 - 2014. Recorded retreats of length, area...
Holocene history of Arctic lakes
Roman, Matěj ; Nývlt, Daniel (advisor) ; Kavan, Jan (referee)
Holocene history of Arctic lakes Abstract Palaeolimnology in the Arctic has achieved a considerable progress in the last decades. The Arctic has changed markedly since the Last Glacial and glacier retreats caused formation of a great number of diverse lake types. Lakes of glacial origin, thermokarst lakes, fluvial lakes and lakes on raised beaches occur most often here. Palaeolimnological methods applied to the high latitude areas are used for the study of the history of individual lakes. Methods of correlation of sedimentary cores and basic interpretation of proxy records such as magnetic susceptibility, diatom biostratigraphy and content of carbon and sulphur were applied on sediments of Garmaksla Lake, Svalbard Archipelago. Climatic and ecological shifts including the Little Ice Age termination and recent warming were registered in proxy values. Keywords: lakes, palaeolimnology, palaeoclimatology, environmental changes, Holocene, Arctic
Paleoclimatic proxies for the Upper Holocene in Central Europe
Heglasová, Veronika ; Treml, Václav (advisor) ; Nývlt, Daniel (referee)
This thesis summarizes findings of the Central European climate evolution during the Late Holocene and approaches to studying the paleoclimates. Indirect sources of evidence about a climatic variable, i.e. proxy data, are used to infer quantitative estimates of temperature or precipitation and can be subdivided into several categories: tree rings record both low- and high-frequency variability of climate with annual resolution; biological (and palynological) proxy data show evidence of longer-term climate changes which are deduced from changes of assemblages/taxa and their ecological preferences. Sedimentary chemistry, including stable isotopes 18 O a 13 C, maintains information on environmental conditions at the time of origin and deposition of sediment (thanks to fractionation and other processes); natural archives are complemented with documentary data which capture the fluctuations of climate up to monthly resolution and also extreme events. There is 44 quantitative paleoclimatic reconstructions in the Central Europe that employ the aforementioned proxy data, although the majority of research articles investigates only approximately the past one thousand years. The temperature and precipitation are reconstructed in the area of the Czech Republic for the past ~600 years. Decadal variability of...
Geomorphological evidence of the Scandinavian glaciation in the Moravian Gate
Pavurová, Zuzana ; Engel, Zbyněk (advisor) ; Nývlt, Daniel (referee)
Geomorphological evidence of the Scandinavian glaciation in the Moravian Gate Abstract This thesis is aimed at area in the Moravian Gate which was covered by continental ice sheets during the Quaternary. The goal of this thesis is to analyze relief and ice-margin landforms in the Moravian Gate. Main parts of this thesis are: current views on the extent of glaciated area, definition ice-marginal landforms, methods my fieldwork, results and discussion. Maps and graphs were created as a part of this thesis. Present relief is very different from pleistocene relief. It is difficult find ice-margin landforms. I agree with extent of pleistocene ice sheet glaciations from Tyráček (2006).
Continental glaciation of the northeastern part of the Frýdlant Spur
Lehejček, Jiří ; Nývlt, Daniel (advisor) ; Engel, Zbyněk (referee)
North-eastern part of Frýdlantský Spur is situated at the northern foothills of the Jizera Mountains. It represents an area, which was at least twice covered by North-European ice sheet during the Middle Pleistocene. At the same time, it is the region whose hills have the summits around the expected altitudinal limit of the maximum ice sheet extent. Therefore, it is a suitable area to study glacial trimline altitude. Schmidt hammer testing was applied to determine different state of rock surface weathering. Obtained R-values were taken as the most relevant data for glacial trimline determination. Nevertheless, other approaches (GIS analysis, outcrops, block fields and erratics mapping) were also incorporated. Interpretation of these approaches gave the altitudinal limit of ice sheets in the north-eastern part of the Frýdlantský Spur at 500 m a. s. l. ± 20 m.
Response of selected rivers of the Bohemian Massif to lithological and structural conditions
Flašar, Jan ; Nývlt, Daniel (advisor) ; Kalvoda, Jan (referee)
Three groups of streams were selected in the area of the Bohemian Massif: the Berounka river with its source streams; the Vltava river with its tributaries the Malše and the Lužnice; the Labe river with its tributaries the Cidlina, the Bystřice and the Javorka. The lithological and tectonical influences to several parameters of the streams were studied. These parameters include: stream gradient, orientation of the stream and sinuosity of the stream. Data were obtained from digital elevation models, aerial photographs, topographical and geological maps. The longitudinal profiles of the streams (in the combination with geological cross-sections), the SL indexes and the gradient/sinuosity graphs were created on the basis of the obtained data. These tools were used for evaluation of the influence of lithology and the tectonics to the streams. The evolution of the streams and the stream-groups was evaluated and compared as well. A strong influence of lithology on the stream gradient was found on most of the analysed streams. The tectonic situation, on the contrary, had strong influence on the orientation of the streams, especially in the resistant rocks. Also, there were selected areas, where was a higher probability of quaternary vertical movements influencing the streams (mountainous areas of the Novohradské...

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2 Nývlt, David
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