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1.
The largest karst cave discovered in a tunnel during motorway construction in Slovenia’s Classical Karst (Kras) 总被引：1，自引：0，他引：1
Karst researchers of the Karst Research Institute ZRC SAZU are regularly consulted during the planning of Slovenia’s motorways
and invited to observe and monitor construction in the karst areas. More than 350 caves have been discovered in the course
of building 60 km of new motorways over the past decade. Access to the most important caves is preserved by concrete tubes
closed with metal covers at the roadside. The largest cave system in a tunnel, named LC-S647, is almost entirely preserved.
The protection of this cave will serve as a good example for the preservation of natural heritage in the future. Construction
work for the motorway uncovered a high degree of karstification. In particular, the discovery of this cave in the Kastelec
tunnel LC-S647 showed the existence of a major cave system in the geological and speleological past. A number of unconnected
passages have also been found. Caves discovered during highway construction have brought new knowledge about the cavernosity
and the geological history of this part of the karst. 相似文献
2.
Three discriminant function models are raised and cross-compared in order to distinguish geochemical patterns characteristic
for the Drava River floodplain sediments. Based on data representing total element concentrations in samples collected from
alluvium (A), terrace (T), and unconsolidated bedrock (B) at the border of a floodplain, four element clusters emerged accounting
for discrimination between the referred groups of sediments. The most prominent is contaminant/carbonate cluster characteristic
for alluvium. The other two are: silicate cluster typical for unconsolidated geological substrate (Neogene sedimentary rocks);
and naturally dispersed heavy metal cluster separating terrace from the former two groups. Models introducing depth intervals
and single profiles as grouping criteria reveal identical sediment-heavy metal matrices. The second important issue of this
paper is possibility of reclassification of samples originally assigned to one of the a priori defined groups of sediments,
based on established geochemical pattern. The mapped geological units can be reconsidered by the post hoc assignments to a
different group if geological border between alluvium and terrace or between terrace and bedrock can not be established geologically
with absolute certainty. 相似文献
3.
Large-scale ancient landslides of the area of more than 5 km2 and volume exceeding 200 × 106 m3 are characteristic features of the valleys incised in the northern periphery of the Crimean Mountains (Ukraine). The largely
affected area is located in the outermost cuesta range of the Crimean Mountains which consists of rigid Sarmatian limestones
overlying weak Middle Miocene and Upper Palaeogene deposits. A giant landslide arose in the Alma water gap as a reflection
of several coincident preparatory factors such as suitable bedrock stratification, smectite-rich bedrock exposed to swelling
activity, presence of faults parallel to the valley trend, and river capture event which preceded the landslide event. The
occurrence of such ancient megaslides is particularly interesting in the area which is characterized by low precipitation
(<500 mm/year) and weak contemporary seismicity. It probably reflects a more dynamic environment in humid phases of the Holocene;
however, seismic triggering along the Mesozoic suture zone cannot be rejected. Compressional features such as gravitational
folds in the central and distal parts of the landslide, which probably correlate with the whole landslide genesis or its significant
reactivation, arose, according to the radiocarbon dating, during the Holocene climatic optimum in the Atlantic period. The
slope deformation has been relatively quiescent since that time, except minor historic reactivization which took place in
the frontal part of the landslide. We suppose that the studied landslide could be classified as a transitional type of slope
deformation with some signs of spreading and translational block slides. 相似文献
4.
5.
Jan Šafanda Philipp Heidinger Helmut Wilhelm Vladimír Čermák 《Hydrogeology Journal》2007,15(2):423-428
As part of the International Continental Scientific Drilling Program (ICDP), the 1.5-km-deep borehole Yaxcopoil-1, located in the Chixculub meteor impact structure in Mexico, has undergone further study after drilling operations ceased. Temperature logs were repeated ten times at intervals 0.3–0.8, 15, 24 and 34 months after borehole shut-in. The logs bear a distinct signature of transient heat transfer by groundwater flow manifested by a gradual distortion of the linear temperature profile when a cold wave of 0.8–1.6°C amplitude was detected propagating downward from 145 to 312 m at a rate of 4–6 m/month. To understand the nature of this moving anomaly, a 20-day monitoring of the cold wave was carried out at a depth of 307 m that showed further cooling of 0.6°C during the first 16 days of the passage followed by temperature stabilisation. As an explanation of this unusual phenomenon, a theory is proposed, whereby the drilling mud has accumulated within the overlying and cooler highly porous and permeable karstic rocks during the drilling and migrates downward. The observed migration rate suggests a permeability higher than 10?11 m2. This indicates a high vulnerability to contamination of the only freshwater aquifer in the Yucatan region. 相似文献
6.
Zusammenfassung Es wird ein einfaches Modell des zykolnalen Wirbels vorgeschlagen und die Beziehung zwischen seiner Intensität, der Form der Stromlinien und der Deformation der frontalen Grenzoberfläche in seiner Nähe diskutiert. Die Arbeit verfolgt das Ziel, die Kriterien der sogenannten dynamischen Klassifikation der aus den meteorologischen Satelliten photographierten Bewölkung zu finden. 相似文献
7.
We present a direct comparison between two different techniques: time-distance helioseismology and a local correlation tracking
method for measuring mass flows in the solar photosphere and in a near-surface layer. We applied both methods to the same
dataset (MDI high-cadence Dopplergrams covering almost the entire Carrington rotation 1974) and compared the results. We found
that, after necessary corrections, the vector flow fields obtained by these techniques are very similar. The median difference
between directions of corresponding vectors is 24°, and the correlation coefficients of the results for mean zonal and meridional
flows are 0.98 and 0.88, respectively. The largest discrepancies are found in areas of small velocities where the inaccuracies
of the computed vectors play a significant role. The good agreement of these two methods increases confidence in the reliability
of large-scale synoptic maps obtained by them. 相似文献
8.
Martin Nekola René Hudec Martin Jelínek Matůš Kocka Petr Kubánek Filip Münz Cyril Polášek Vojtěch Šimon Jan Štrobl 《Experimental Astronomy》2010,28(1):79-85
We report on two small aperture robotic telescopes called BART and D50 operated in Ondřejov. Both telescopes are capable of
automatic observation of gamma ray burst (GRB) optical afterglows. Coordinates of GRBs are taken from alerts distributed via
Internet. Telescopes observe other interesting high energy sources when there is not any alert. The smaller telescope BART
has aperture D = 254 mm. The bigger telescope D50 has a primary mirror of diameter D = 500 mm. Both telescopes are controlled
by free software package RTS2 and are accessible through Internet. We describe the two telescopes and related software and
show some results such as our first observed optical counterpart of GRB. 相似文献
9.
New spherical integral formulas between components of the second- and third-order gravitational tensors are formulated in this article. First, we review the nomenclature and basic properties of the second- and third-order gravitational tensors. Initial points of mathematical derivations, i.e., the second- and third-order differential operators defined in the spherical local North-oriented reference frame and the analytical solutions of the gradiometric boundary-value problem, are also summarized. Secondly, we apply the third-order differential operators to the analytical solutions of the gradiometric boundary-value problem which gives 30 new integral formulas transforming (1) vertical-vertical, (2) vertical-horizontal and (3) horizontal-horizontal second-order gravitational tensor components onto their third-order counterparts. Using spherical polar coordinates related sub-integral kernels can efficiently be decomposed into azimuthal and isotropic parts. Both spectral and closed forms of the isotropic kernels are provided and their limits are investigated. Thirdly, numerical experiments are performed to test the consistency of the new integral transforms and to investigate properties of the sub-integral kernels. The new mathematical apparatus is valid for any harmonic potential field and may be exploited, e.g., when gravitational/magnetic second- and third-order tensor components become available in the future. The new integral formulas also extend the well-known Meissl diagram and enrich the theoretical apparatus of geodesy. 相似文献
10.
Gregor Muri Branko Čermelj Radojko Jaćimović Tina Ravnikar Andrej Šmuc Janja Turšič Polona Vreča 《Journal of Paleolimnology》2018,59(4):411-426
Increased eutrophication was recently observed in the 5th (5J) and 6th (6J) Triglav Lakes, two remote Slovenian mountain lakes. Sediment phosphorus (P) pools were analysed and potential external P sources affecting the lakes (atmospheric deposition, terrestrial export and nearby hut) evaluated, to assess the effects of internal and external changes on the lakes. A sequential extraction procedure was used to quantify five P fractions from the sediments: adsorbed (NH4Cl–P), redox-sensitive (BD–P), aluminium- (NaOH–P) and calcium- (HCl–P) bound, and refractory organic (Res–P) P. Total phosphorus (TP) contents in surface sediment of 5J and 6J were 1430 and 641 µg P g?1 dry weight sediment (dw), respectively. TP varied with depth in 5J sediments, but displayed no discernible pattern, whereas it decreased steadily downcore in 6J. Contents of all P forms were distinctly higher in 5J than 6J, but their rank order and relative abundances were similar in the two lakes. Res–P was the most abundant P fraction, followed by HCl–P. Together, the two P forms accounted for nearly 80 and 90% of TP in 5J and 6J sediments, respectively. BD–P and NaOH–P were less abundant, with each fraction accounting for 3 to 9% of TP, whereas NH4Cl–P was least abundant. Atmospheric deposition and terrestrial export were substantial sources of P for the lakes. Delivery of the former was estimated to be at least 7.5 mg P m?2 yr?1 and the latter around 20 mg P m?2 yr?1. We concluded that P was not retained in the catchment effectively, likely because of only slightly acidic soil pH (5.9), relatively low aluminium content and high organic matter content (53%) in soils, resulting in higher vulnerability of the studied lakes to eutrophication. The mountain hut could also be a significant source of P for the lakes. Each year, it could potentially contribute ~12 kg of soluble P to the environment, but the true impact of the hut on lake trophic status remains unclear. 相似文献