Book Review Beyond Plate Tectonics, eds. David A. Yuen, Shingenori Maruyama, Shun-Ichiro Karota, and Brian F. Windley     

Marek Lewandowski 《Pure and Applied Geophysics》2009,166(4):721-722

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Book Review: The Rock Physics Handbook: Tools for Seismic Analysis in Porous Media by G. Mavko, T. Mukurji, and J. Dvorkin     

Marek Lewandowski 《Pure and Applied Geophysics》2009,166(3):517-517

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Organosilane occurrence in irghizite samples from the Zhamanshin impact crater,Kazakhstan     

Marek ZBIK  Marek JASIENIAK  Roger St.C. SMART 《Meteoritics & planetary science》2000,35(5):943-947

Abstract— The composition of surface deposits on vesicle walls in irghizites (i.e., impact glasses at site) from the Zhamanshin meteorite crater were studied using time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). The cavity walls are unique interfaces for condensation of gases from the superheated, high‐silica melt during the impact. Initially, signals from the cavity wall are dominated by hydrocarbon fragments whereas the glass fracture face surrounding the cavity gave only signals corresponding to glass components. After 12 h in ultra high vacuum (UHV), signals from the cavity wall are dominated by peaks corresponding to fragments normally measured from organosilanes and organosiloxanes with the majority of the hydrocarbon signals markedly reduced. Characteristic hydrocarbon fragments are now observed on the glass fracture surface next to the cavity in an annulus around the cavity perimeter. There are also minor signals in this region from organosilanes and organosiloxanes. In contrast, four tektites (Australites) (i.e., glassy distal ejecta) gave no organosilane or organosiloxane signals after the same preparation and vacuum evaporation procedure. These species appear to be formed only at the impact site where higher levels of organic material are likely to be present in soil and are trapped before evaporation. This appears to be the first report of naturally occurring silicon‐organic compounds.  相似文献   

A site‐consistent method to quantify sufficiency of alternative IMs in relation to PSDA          下载免费PDF全文

Somayajulu L. N. Dhulipala  Adrian Rodriguez‐Marek  Shyam Ranganathan  Madeleine M. Flint 《地震工程与结构动力学》2018,47(2):377-396

In probabilistic seismic demand analysis, evaluation of the sufficiency of an intensity measure (IM) is an important criterion to avoid biased assessment of the demand hazard. However, there exists no metric to quantify the degree of sufficiency as per the criterion of Luco and Cornell (2007). This paper proposes a site‐specific unified measure for degree of sufficiency from all seismological parameters under consideration using a total information gain metric. This unified metric for sufficiency supports not only comparison of the performance of different IMs given a response quantity but also assessment of the performance of a particular IM across different response quantities. The proposed sufficiency metric was evaluated for a 4‐story steel moment frame building, and the influence of ground motion selection on the degree of sufficiency was investigated. It was observed that ground motion selection can have a significant impact on IM sufficiency. Because computing the total information gain requires continuous deaggregation across the IM space, an approximate deaggregation technique that allows for a more practical estimation of marginal deaggregation probabilities is proposed. It is expected that the total information gain metric proposed in this paper will aid in understanding the efficiency‐sufficiency relation, thus enabling the selection of a proper scalar IM for a given site and application in probabilistic seismic demand analysis.  相似文献   

Application of Mössbauer spectroscopy,multidimensional discriminant analysis,and Mahalanobis distance for classification of equilibrated ordinary chondrites     

Marek Wo niak  Jolanta Ga&#x;&#x;zka‐Friedman  Przemys&#x;aw Duda  Martyna Jakubowska  Patrycja Rzepecka  &#x;ukasz Karwowski 《Meteoritics & planetary science》2019,54(8):1828-1839

Mössbauer spectra of equilibrated ordinary chondrites consist of two doublets due to paramagnetic iron present in olivines and pyroxenes and two sextets due to magnetically ordered iron present in metallic phases and troilite. The spectral areas of the different mineralogical phases found by Mössbauer spectroscopy in meteorites are proportional to the number of iron atoms in this mineralogical phase. This property of Mössbauer spectra can be the basis for constructing a method for the classification of ordinary chondrites. This idea was first explored at the Mössbauer Laboratory in Kanpur. This group suggested a qualitative method based on 2‐dimensional plots of Mössbauer spectral areas and thus classified properly some meteorites. We constructed a quantitative method using Mössbauer spectral areas, multidimensional discriminant analysis, and Mahalanobis distance (4M method) to determine the probability of a meteorite to be of type H, L, or LL. Based on 59 Mössbauer spectra, we calculated by the 4M method, S _cluster , the level of similarity of the Goronyo meteorite to the clusters. On the plot of ferrosilite versus fayalite, the point representing Goronyo is located on the border between H and L areas. Calculated by the 4M method, the meteorite Goronyo is 32% similar to type H, 75% to type L, and 11% to type LL. Additional mineralogical analyses suggested that the Goronyo meteorite would be classified as type L, although it was originally reported as type H in the Meteoritical Bulletin Database.  相似文献   

Spring water table depth mediates within-site variation of soil temperature in groundwater-fed mires     

Michal Horsák  Veronika Horsáková  Marek Polášek  Radovan Coufal  Petra Hájková  Michal Hájek 《水文研究》2021,35(7):e14293

Groundwater-dependent ecosystems represent globally rare edaphic islands of scattered distribution, often forming areas of regionally unique environmental conditions. A stable groundwater supply is a key parameter defining their ecological specificity, promoting also soil thermal buffering. Still, a limited number of studies dealt with the importance of water temperature in mire ecosystems and virtually no data exist on within-site variation in the temperature buffer effect. Three temperature dataloggers, placed in patches potentially differing in groundwater supply, were installed in each of 19 Western Carpathian spring mire sites from May 2019 to July 2020. Spring source plots statistically differed in water temperature parameters from the plots located towards the spring mire margin, which did not significantly differ from one another. At the majority of sites, the temperature values changed gradually from spring source to mire margins, fitting the pattern expected in the groundwater temperature buffering scenario. Dataloggers placed in the spring sources were the most distinctive from the others in thermal buffering parameters in conditional principal component analysis. The difference between the spring source and its margin was on average 3.25 °C for 95th percentile of the recorded water temperature data points (i.e. warm extremes) and 1.91 °C for 5th percentile (i.e. cold extremes). This suggests that if the temperature at spring source area is considered, thermal buffering within a site may mitigate mainly warm extremes. Thus, our data may provide an important baseline for predictions of possibly upcoming changes in spring mire hydrology caused by climate change. Both warming and precipitation decrease can give rise to the loss or substantial reduction of buffering effect if the contrasting parameters now recorded at the central part shift to those found towards the margins of groundwater-fed areas.  相似文献   

Bianchi Cosmologies as Dynamical Systems     

Andrzej J. Maciejewski  Marek Szydłowski 《Celestial Mechanics and Dynamical Astronomy》1999,73(1-4):17-24

We discuss specific properties of dynamical systems originating from cosmology and relativity. In particular, we present results of our study of the Bianchi class A cosmological models. We introduce new variables in which the Hamiltonian constraint for all the class A models is solved algebraically. We present results of dimension reduction of the investigated models. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A palaeomagnetic study of fracture fills in the Holy Cross Mountains of Central Poland and its application in dating tectonic processes     

Marek Lewandowski 《Geophysical Journal International》1999,137(3):783-792

Calcite and sedimentary fills in fractures cutting the Upper Devonian carbonates in the Holy Cross Mountains (HCM) were dated palaeomagnetically by comparison with the apparent polar wander path (APWP). Haematite-bearing calcite possessed well-defined components of natural remanent magnetization (NRM), which were preserved under thermal demagnetization to temperatures of approximately 500 °C, when specimens disintegrated. Although not completely demagnetized, some specimens revealed a stable NRM component before destruction, thus making a component analysis possible. Five components were determined using density point distribution and cluster analysis. One has a mean that is similar to the present-day local geomagnetic vector. The remaining four components yielded palaeomagnetic poles located at: A (70.3°S, 5.5°E), B (71.3°S, 31.2°E), C (48.7°S, 351.0°E, virtual geomagnetic pole), and D (11.6°S, 312.3°E). Antipodal polarities found in the fracture fills, together with dissimilarities in magnetization found in calcite and hosting carbonates, indicate the lack of simultaneous remagnetization, and different times of remanence acquisition for the rocks under comparison. Taking both palaeomagnetically inferred palaeolatitudes and regional tectonics into consideration, a Mesozoic (Cretaceous?) age is estimated for palaeopoles A and B, a Permian age for pole C, and a Carboniferous age for pole D. These age determinations are in line with the calcite ages estimated from isotopic studies. A comparative palaeomagnetic study performed on a well-dated Upper Devonian neptunian dyke of limestone and a Lower Triassic clastic vein yielded virtual geomagnetic poles (VGPs) close to the APWP for Baltica. Generally, the remanence from fracture fills may be useful for dating related tectonics, karst phenomena and mineralization processes.  相似文献   

Analysis of the primary and secondary microseisms in the wavefield of the ambient noise recorded in northern Poland     

Simone Lepore  Marek Grad 《Acta Geophysica》2018,66(5):915-929

Seasonal changes of the primary and secondary microseisms were analysed in the wavefield of the ambient noise recorded during the entire 2014 at the “13 BB star” array located in northern Poland, composed of thirteen, symmetrically arranged, broadband seismic stations. To that, spectral analysis, seismic interferometry, surface scalar wind speed distribution, and beamforming were used. Spectral analysis allowed to observe that a splitting of the secondary microseism peak was present in winter and autumn, and that the primary microseism peak was visible in spring, summer and autumn. Using seismic interferometry, the long-term characteristics of the noise wavefield were recognized. The seasonal variations of the secondary microseism source were described by means of the analysis of the surface scalar wind speed for each month. The splitting of the secondary peak was attributed to the interaction of a strong wind blowing from the North Sea with a weak wind blowing from the Baltic Sea. The seasonal variations of the primary microseism peak were characterized through the frequency-domain beamforming. The peak was identified during spring, summer and autumn, when the generated wavefield was coming from the Baltic Sea. The velocity of the wavefield was evaluated within the 2.0–5.0 km/s range. The described mechanism of generation of the microseisms, based on the interaction of the nearby winds, was found to be consistent with the models reported in the literature.  相似文献   

Sub-annual moraine formation at an active temperate Icelandic glacier     

Benjamin M.P. Chandler  Samuel J.P. Chandler  David J.A. Evans  Marek W. Ewertowski  Harold Lovell  David H. Roberts  Martin Schaefer  Aleksandra M. Tomczyk 《地球表面变化过程与地形》2020,45(7):1622-1643

This paper presents detailed geomorphological and sedimentological investigations of small recessional moraines at Fjallsjökull, an active temperate outlet of Öræfajökull, southeast Iceland. The moraines are characterized by striking sawtooth or hairpin planforms, which are locally superimposed, giving rise to a complex spatial pattern. We recognize two distinct populations of moraines, namely a group of relatively prominent moraine ridges (mean height ~1.2 m) and a group of comparatively low-relief moraines (mean height ~0.4 m). These two groups often occur in sets/systems, comprising one pronounced outer ridge and several inset smaller moraines. Using a representative subsample of the moraines, we establish that they form by either (i) submarginal deformation and squeezing of subglacial till or (ii) pushing of extruded tills. Locally, proglacial (glaciofluvial) sediments are also incorporated within the moraines during pushing. For the first time, to our knowledge, we demonstrate categorically that these moraines formed sub-annually using repeat uncrewed aerial vehicle (UAV) imagery. We present a conceptual model for sub-annual moraine formation at Fjallsjökull that proposes the sawtooth moraine sequence comprises (i) sets of small squeeze moraines formed during melt-driven squeeze events and (ii) larger push moraines formed during winter re-advances. We suggest the development of this process-form regime is linked to a combination of elevated temperatures, high surface meltwater fluxes to the bed and emerging basal topography (a depositional overdeepening). These factors result in highly saturated subglacial sediments and high porewater pressures, which induces submarginal deformation and ice-marginal squeezing during the melt season. Strong glacier recession during the summer, driven by elevated temperatures, allows several squeeze moraines to be emplaced. This process-form regime may be characteristic of active temperate glaciers receding into overdeepenings during phases of elevated temperatures, especially where their englacial drainage systems allow efficient transfer of surface meltwater to the glacier bed near the snout margin. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献