Kinematic analysis and analogue modelling of the Passeier- and Jaufen faults: implications for crustal indentation in the Eastern Alps     

Stefan Luth  Ernst Willingshofer  Marten ter Borgh  Dimitrios Sokoutis  Jozua van Otterloo  Arno Versteeg 《International Journal of Earth Sciences》2013,102(4):1071-1090

Crustal deformation in front of an indenter is often affected by the indenter’s geometry, rheology, and motion path. In this context, the kinematics of the Jaufen- and Passeier faults have been studied by carrying out paleostress analysis in combination with crustal-scale analogue modelling to infer (1) their relationship during indentation of the Adriatic plate and (2) their sensitivity in terms of fault kinematics to the geometry and motion path of Adria. The field study reveals mylonites along the Jaufen fault, which formed under lower greenschist facies conditions and is associated with top-to-the-west/northwest shear with a northern block down component. In addition, a brittle reactivation of the Jaufen shear zone under NNW–SSE to NW–SE compressional and ENE–WSW tensional stress conditions was deduced from paleostress analysis. The inferred shortening direction is consistent with fission track ages portraying Neogene exhumation of the Meran-Mauls basement south of the fault. Along the Passeier fault, deformation was only brittle to semi-ductile and paleostress tensors record that the fault was subjected to E–W extension along its northern segment varying into NW–SE compression and sinistral transpression along its southern segment. In the performed analogue experiments, a rigid, triangular shaped indenter was pushed into a sand pile resulting in the formation of a Passeier-like fault sprouting from the indenter’s tip. These kinds of north-trending tip faults formed in all experiments with shortening directions towards the NW, N, or NE. Consequently, we argue that the formation of the Passeier fault strongly corresponds to the outline of the Adriatic indenter and was only little affected by the indenter’s motion path due to induced strain partitioning in front of the different indenter segments. The associated fault kinematics along the Passeier fault including both E–W extension and NNW to NW shortening, however, is most consistent with a northward advancing Adriatic indenter.  相似文献   

Trends and evolution of contamination in a well-dated water reservoir sedimentary archive: the Brno Dam, Moravia, Czech Republic     

Jan Sedláček  Ondřej Bábek  Tomáš Matys Grygar 《Environmental Earth Sciences》2013,69(8):2581-2593

The sedimentary record from dams can provide important information about stratigraphy and pollution history of densely populated river basins. The Brno Dam is a small reservoir within the Morava River catchment (Czech Republic) accumulating lacustrine sediments since 1940 (dam filling). The stratigraphy of the dam sediments was studied using multiproxy stratigraphic analysis (X-ray densitometry, bulk magnetic susceptibility, diffuse spectral reflectance and cation-exchange capacity) of five sediment cores supported by ground-penetration radar sections. Concentrations of heavy metals were studied by X-ray fluorescence analysis. The thickness of the dam sediments decreases from 220 cm in the proximal part, near the feeder, to only 10 cm in the distal part, near the dyke. Sediments consist predominantly of finely-laminated silty sands, silts and clays. The sedimentation rate for the last ~22 years, inferred from ¹³⁷Cs dating, decreases from 4.2 cm per year in the proximal part of the dam to 0.29 cm per year in its distal part. Distinct long-term trends were found in the depth profiles of heavy metal concentrations. The heavy metal contents increase significantly after 1940 in all cores, with peak concentrations confined to layers deposited in the 1960s and 1980s. A decreasing trend occurred after 1989 (the decline in Czech heavy industry). The results also show that heavy metal contamination is dependent on lithology (hyperpycnal flow layers related to floods). Increased concentrations of phosphorus in the sediments indicate long-term eutrophication of the dam. Despite the recent decreasing trends in heavy metal concentrations the phosphorus contents remain high in recent years and have caused persisting problems with algal growth in the dam mentioned by previous authors.  相似文献   

Leaching capabilities of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) at different concentrations and pH for some major and trace metals from coal and coal fly ash     

M. Ishaq  F. Akbar Jan  M. Shakirullah  I. Ahmad  Hina Ali 《Arabian Journal of Geosciences》2013,6(11):4109-4118

In the present study, coal from Chakwal (Pakistan) was leached with an aqueous solutions of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) of different concentrations. The effect of stirring time, concentration and pH was studied on the leaching of different metals from coal. The physicochemical parameters indicated that the coal was of reasonably good quality. The results indicated that with increase in time duration, the extraction of metals increased. In most of the cases, metal concentration increased in the leachate with increasing the concentration of the leaching agents. DPTA was found to be the best leaching agent for most of the metals. Higher extraction of metals from coal fly ash indicated that coal organic matter has a pronounced effect on the leaching. Higher concentration of metals was extracted from virgin coal and coal fly ash at low pH (p?>?0.00) as compared to high pH. DPTA extracted metals in higher concentration from virgin coal and coal fly ash at low pH as compared to ICl. Based on the present study, the most leached metals were Fe, Cu, Mn and the least were Pb, Ni, Cd and Cr.  相似文献   

Joint Consistent Mapping of High-Dimensional Geochemical Surveys   总被引：1，自引：0，他引：1  

R. Tolosana-Delgado  K. G. van den Boogaart 《Mathematical Geosciences》2013,45(8):983-1004

Geochemical surveys often contain several tens of components, obtained from different horizons and with different analytical techniques. These are used either to obtain elemental concentration maps or to explore links between the variables. The first task involves interpolation, the second task principal component analysis (PCA) or a related technique. Interpolation of all geochemical variables (in wt% or ppm) should guarantee consistent results: At any location, all variables must be positive and sum up to 100 %. This is not ensured by any conventional geostatistical technique. Moreover, the maps should ideally preserve any link present in the data. PCA also presents some problems, derived from the spatial dependence between the observations, and the compositional nature of the data. Log-ratio geostatistical techniques offer a consistent solution to all these problems. Variation-variograms are introduced to capture the spatial dependence structure: These are direct variograms of all possible log ratios of two components. They can be modeled with a function analogous to the linear model of coregionalization (LMC), where for each spatial structure there is an associated variation matrix describing the links between the components. Eigenvalue decompositions of these matrices provide a PCA of that particular spatial scale. The whole data set can then be interpolated by cokriging. Factorial cokriging can also be used to map a certain spatial structure, eventually projected onto those principal components (PCs) of that structure with relevant contribution to the spatial variability. If only one PC is used for a certain structure, the maps obtained represent the spatial variability of a geochemical link between the variables. These procedures and their advantages are illustrated with the horizon C Kola data set, with 25 components and 605 samples covering most of the Kola peninsula (Finland, Norway, Russia).  相似文献   

A Spectral Analysis Based Methodology to Detect Climatological Influences on Daily Urban Water Demand     

Jan Adamowski  Kaz Adamowski  Andreas Prokoph 《Mathematical Geosciences》2013,45(1):49-68

Urban water demand (UWD) is highly dependent on interacting natural and socio-economic factors, and thus a wide range of data analysis and forecasting methods are required to fully understand the issue. This study applies, for the first time, the continuous wavelet transform to determine changes in the temporal pattern of UWD and its potential meteorological drivers for three major Canadian cities: Calgary, Montreal, and Ottawa. This analysis is complemented by Fourier and cross-spectral analysis to determine inter-relationships and the significance of the patterns detected. The results show that the annual (365 days) cycle provides the most consistent and significant relationship between UWD and meteorological drivers. Wavelet analysis shows that UWD is only sensitive to air temperature in the summer months when mean daily temperatures are greater than 10 to 12 °C. For the three cities studied, the UWD increases by between 10 ML (Montreal) and 50 ML (Calgary) per day with every 1 °C increase in air temperature. In an area with low precipitation (Calgary), there is an inverse relationship between UWD and precipitation during summer months. Wavelet transform and Fourier analysis also detected a 7-day cycle in UWD, particularly in the more industrialized city of Montreal, which is related to the working week. In general, applying the season dependent linear relationships between UWD and temperature is suggested as perhaps being more appropriate and potentially successful for forecasting, rather than continuous complex nonlinear algorithms that are designed to explain variability in the entire UWD record.  相似文献   

Middle-Late Alpine thermotectonic evolution of the southern Rhodope Massif,Greece     

Andor L.W. Lips  Stanley H. White  Jan R. Wijbrans 《Geodinamica Acta》2013,26(5):281-292

Abstract

The transition from the Alpine tectonic assembly to the exhumation of the units in the Rhodope metamorphic province in northernmost Greece has been refined by ⁴⁰Ar/³⁹Ar laserprobe mica analyses. Preservation of pre-Alpine (~ 280 Ma and 145 Ma) muscovite cooling ages at the western margin of the Rhodope indicate that subsequent events failed to reset the argon system thermally in white mica in the outcropping basement of this region. The central and eastern Rhodope are characterized by white mica cooling ages of 40–35 Ma with ages gradually decreasing to ca. 15 Ma near the eastern margin of the Strymon Valley. The Eo-Oligocene ages reflect the regional exhumation of the metamorphosed units to shallow crustal levels, with corresponding temperatures below ca. 350 °C, by 40–35 Ma. The younger cooling ages are attributed to the initiation and subsequent operation of the Strymon-Thasos detachment system since ca. 30 Ma. This study provides a crucial contribution to future regional tectonic models for the Rhodope region as it recognizes an early stage of development of the Strymon-Thasos detachment system, and has constrained the regional exhumation of the Rhodope metamorphic province since 40 Ma indicating that the regionally observed amphibolite facies metamorphism had terminated by this time. © 2000 Editions scientifiques et médicales Elsevier SAS  相似文献   

Geochemical and electron paramagnetic characteristics of quartz from a multi-stage vein environment, Cowarra gold deposit, New South Wales     

K. G. McQueen  Aung Pwa  J. C. van Moort 《Journal of Geochemical Exploration》2001,72(3)

The characterisation of quartz using trace element geochemistry and electron paramagnetic resonance measurements has been tested for different generations of quartz veining in the multi-stage hydrothermal vein system at Cowarra. Quartz closely associated with gold mineralisation can be distinguished from earlier and later quartz generations in the mineralised environment, and both types can be distinguished from regional, barren quartz veins. These separate stages of quartz veins are also recognised from their fluid inclusion characteristics. Geochemical differences in the quartz partly reflect the presence of minor mineral inclusions, particularly sulfides and arsenopyrite.The study highlights the importance of understanding the paragenetic sequence of quartz vein development in a mineralised environment and the need for careful, thorough sampling before attempting geochemical and EPR characterisation of quartz as an exploration technique.  相似文献   

No evidence for an early seventeenth‐century Indian sighting of Kepler's supernova (SN1604)     

R.H. van Gent 《Astronomische Nachrichten》2013,334(3):300-306

In a recent paper in this journal, Sule et al. (2011) argued that an early 17th‐century Indian mural of the constellation Sagittarius with a dragon‐headed tail indicated that the bright supernova of 1604 was also sighted by Indian astronomers. In this paper it will be shown that this identification is based on a misunderstanding of traditional Islamic astrological iconography and that the claim that the mural represents an early 17th‐century Indian sighting of the supernova of 1604 has to be rejected. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Response and recovery of the Eel River, California, and its tributaries to floods in 1955, 1964, and 1997     

Jan Sloan  Jerry R. Miller  Nicholas Lancaster 《Geomorphology》2001,36(3-4)

Northwestern California is prone to regional, high magnitude winter rainstorms, which repeatedly produce catastrophic floods in the basins of the northern Coast Ranges. Major floods on the Eel River in 1955 and 1964 resulted in substantial geomorphic changes to the channel, adjacent terraces, and tributaries. This study evaluated the changes and the effects of a moderate flood in 1997 through field observations and examination of aerial photographs that spanned from 1954 to 1996. The purpose was to document the nature and magnitude of geomorphic responses to these three floods and assess the rates and controls on the recovery of the Eel River and its tributaries. Channel widening from extensive bank erosion was the dominant geomorphic change along the lower Eel River during major floods. As a result of the 1964 flood, the largest amount of widening was 195 m and represented an 80% change in channel width. Channel narrowing characterized the periods after the 1955 and 1964 floods. More than 30 years after the 1964 flood, however, the river had not returned to pre-flood width, which suggests that channel recovery required decades to complete. A long recovery time is unusual given that the Eel River is located in an area with a “superhumid” climate and has an exceptionally high sediment yield. This long recovery time may reflect highly seasonal precipitation and runoff, which are concentrated in 3–5 months each winter. In contrast to the main stem of the Eel River, the dominant effects of floods on the tributaries of the Eel River were rapid aggradation of channel bed and valley floor followed by immediate downcutting. Dendrogeomorphic data, aerial photographs, and field observations indicate that thick wedges of gravel, derived largely from hillslope failures in upper reaches of the tributaries, are deposited at and immediately upstream of the mouths of tributaries as the stage of the Eel River exceeded that of the tributaries during major floods. In the waning stages of the flood, the tributaries cut through the gravel at a rate equal to the lowering of the Eel and generated unpaired terraces and nickpoints. The complete process of deposition and incision can occur within a few days of peak discharge. Although reworking of some sediment on the valley floor may continue for years after large floods, channel morphology in the tributaries appears to be a product of infrequent, high magnitude events. The morphology of the tributary channel also appears to be greatly influenced by the frequency and magnitude of mass wasting in headwater areas of small basins.  相似文献   

The Palaeomagnetism of the Stormberg Lavas, II. The Behaviour of the Magnetic Field During a Reversal     

J. S. V. van  Zijl  K. W. T. Graham  A. L. Hales 《Geophysical Journal International》1962,7(2):169-182

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