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41.
Relu D. Roban Mihai N. Ducea Vlad I. Mihalcea Ioan Munteanu Victor Barbu Mihaela C. Melinte-Dobrinescu Cornel Olariu Mihai Vlăsceanu 《Basin Research》2023,35(1):244-270
We present new sedimentological, petrographical, palaeontological and detrital zircon U–Pb data on late Oligocene–early Miocene sedimentary rocks of the thin-skinned thrust belt of East Carpathians. These data were acquired to reconstruct the sedimentary routing system for two compositionally different turbidite fans made of the regionally extensive Kliwa and Fusaru formations. On the eastern margin of the Moldavides foreland basin, large low-gradient river systems draining the East European Platform provided well-sorted quartz-rich sand forming deltas on wide shallow shelves and thick Kliwa submarine fans. Due to the westward subduction of a thinned continental plate, the western basin margin was characterized by short, steep-gradient routing systems where sediment transport to deep water was mainly through hyperpycnal flows. The Getic and Bucovinian nappes of the East Carpathians and the exhumed Cretaceous–Early Palaeogene orogenic wedge fed Fusaru fans with poorly sorted lithic sand. The Fusaru fans trend northwards in the foredeep basin having an elongate depocentre, interfingering and then overlapping on the distal part of the Kliwa depositional system due to the eastward advance of the Carpathian fold-and-thrust belt. A smaller sediment input is supplied by southern continental areas (i.e. Moesian Platform, North Dobrogea and potentially the Balkans). In general, the sandstone interfingering between distinct basin floor fan systems is less well documented because the facies would be similar and there are not many systems that have a distinct sediment provenance like Kliwa and Fusaru systems. This case study improves the understanding of regional palaeogeography and sedimentary routing systems and provides observations relevant here or elsewhere on the interfingering turbidite fan systems. 相似文献
42.
A particular multi-angle averaging theorem for systems admitting a finite Fourier expansion of the field is presented, together
with its application to the problem of motion around an oblate planet (the J2 problem), in harmonic oscillator formulation. This method of approximate integration has the advantage of working with (close
on) directly measurable elements.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
43.
M. Răcuciu C. Iftode S. Miclăuş 《International Journal of Environmental Science and Technology》2018,15(6):1233-1242
The biological impact of microwaves exposure on biosphere is presently an important research subject. With the significant increase of communications technology use, of industrial and military activities which involve radiofrequency radiation, electromagnetic pollution became very intense in the last years. The aim of the present work was to investigate the genotoxic influence of microwaves on Zea mays seeds. They were exposed in controlled conditions for different durations at 1 GHz continuous wave providing a low specific absorption rate of energy. Post-exposure the mitotic- and chromosomal aberrations indexes were determined. Qualitatively, a wide range of abnormal mitotic stages were detected in cells of exposed seeds in comparison with the control. Quantitatively, slight stimulatory effect on mitotic division process, expressed by an enhanced percentage of dividing cells (increased of 26% for 180 min exposure), for all exposed samples was revealed, while lowered level of induced chromosomal aberrant cells percentage (up to 2.14%) was also found. The aberrations percentage and mitotic index increased in time-dependent manner on exposure dose. 相似文献
44.
Cheval Sorin Bulai Ana Croitoru Adina-Eliza Dorondel Ștefan Micu Dana Mihăilă Dumitru Sfîcă Lucian Tișcovschi Adrian 《Theoretical and Applied Climatology》2022,149(1-2):253-272
Theoretical and Applied Climatology - In the last decades, anthropogenic drivers have significantly influenced the natural climate variability of Earth’s atmosphere. Climate change has become... 相似文献
45.
The Groapa Vântului (Wind’s Dip) landslide, situated in the Buz?u Carpathians, on the right-hand slope of the Siriu Reservoir, occurred in April 2006, after the first local movements were signaled in September–October 2005. It represents a reactivation of an older, apparently relict (and well covered by a secular beech forest) landslide, which blocked Siriu Reservoir for several weeks and caused a major change in the sedimentation regime downstream of it. The volume of the displaced material reached almost 2.5 million m3, affecting a surface of more than 250,000 m2 and reducing the reservoir’s volume by almost 2 million m3. The landslide developed on a lithological contact of Paleogene flysch formations and features steep (40–50°) and high (up to 30 m) scarps, as well as complex inner sectors, of rotational, translational, and compresional movement. The assessment of landslide’s morphodynamic behavior is based on repeated geomorphological field mapping and measurements, differential Global Positioning System, and total station profiles, and mobile and fixed landmarks. This preliminary assessment contributes to the understanding of the behavior of old, peri-glacial landslide reactivations and also represents progress towards a better hazard assessment. 相似文献
46.
A study of the orbital period variation of the W UMa system CK Bootis is made using an extended observational time base. The biperiodicity of the orbital period modulation is emphasized. Both detected periodicities (24.14 yr and 10.62 yr) cannot be explained through the light-time effect unless the companion would be a white dwarf as suggested by other authors, too. Moreover, we also argue that, nowadays at least, it seems that there is no causal relation between the orbital period variation and the recently discovered visual companion. Consequently, we infer that at least one of the two periodicities may be related to the magnetic activity cycles in the component stars of CK Boo, while the other periodicity could be related to the presence of a fourth companion in the system. 相似文献
47.
48.
Ovreiu Adriana Bianca Bărsoianu Iulian Andrei Nistor Constantin Nedelea Alexandru Comănescu Laura 《Natural Hazards》2019,99(1):117-140
Natural Hazards - Rockfalls represents a sudden, extremely important geomorphological hazard and may become a threat for people’s life, as well as goods and transport. The present study aims... 相似文献
49.
Perception of flood risk in Danube Delta,Romania 总被引:1,自引:1,他引:0
For exposed and vulnerable communities, the perception of natural risk is an essential link in the analysis of man–environment
coping relationship and also an important parameter in the quantification of complex vulnerability as a central predictive
variable in the risk equation. The topic of flood risk in related perception is of considerable interest, as some recently
published papers have proven (Messner and Meyer 2005, 2006; Raaijmakers et al. 2008). The aim of the current study is to reveal the conscious and unconscious attitudes towards the flood risk for the inhabitants
of the Danube Delta/Romania. These attitudes, defined by different degrees of psychological vulnerability, represent the background
for a series of psycho-behavioural patterns that generate certain adjustment mechanisms and strategies. Application of a specially
designed questionnaire and the statistical analysis of the results revealed two psychological factors as essential in establishing
the psychosocial vulnerability degree of the interviewed subjects: (i) an internal control factor and (ii) an external control
factor. The persons characterized by inner control have a significantly reduced general anxiety level in comparison to individuals
with the control factor placed externally. As confidence diminishes, it increases the tendency of the individual to rely on
the external factors for support and security. The lack of resources (indicating lower resilience) and mistrust in the support
given emphasizes non-adaptive behaviours.
相似文献
Iuliana ArmaşEmail: |
50.
Taking as an example six main rivers that drain the western flank of the Eastern Carpathians, a conceptual model has been developed, according to which fluvial bed sediment bimodality can be explained by the overlapping of two grain size distribution curves of different origins. Thus, for Carpathian tributaries of the Siret, coarse gravel joins an unimodal distribution presenting a right skewness with enhanced downstream fining. The source of the coarse material distributions is autohtonous (by abrasion and hydraulic sorting mechanisms). A second distribution with a sandy mode is, in general, skewed to the left. The source of the second distribution is allohtonous (the quantity of sand that reaches the river‐bed through the erosion of the hillslope basin terrains). The intersection of the two distributions occurs in the area of the 0·5–8 mm fractions, where, in fact, the right skewness (for gravel) and left skewness (for sand) histogram tails meet. This also explains the lack of particles in the 0·5–8 mm interval. For rivers where fine sediment sources are low, the 0·5–8 mm fractions have a higher proportion than the fractions under 1 mm. For the Siret River itself, bed sediment bimodality is greatly enhanced due to the fact that the second mode is more than 25% of the full sample. As opposed to its tributaries, the source of the first mode, of gravel, is allohtonous to the Siret river, generated by the massive input of coarse sediment through the Carpathian tributaries, while the second mode, of the sands, is local. In this case we can also observe that the two distributions of particles of different origins overlap in the 0·5–8 mm fraction domain, creating the illusion of ‘particle lack’ in the fluvial bed sediments. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献