Editorial     

John Leibacher  Takashi Sakurai  Lidia van Driel-Gesztelyi 《Solar physics》2005,229(1):3

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Geodynamic setting of gold deposits in Eastern and Central Trans-Baikal (Chita Region, Russia)   总被引：1，自引：0，他引：1  

Yu. A. Zorin  Lidia D. Zorina  A. M. Spiridonov  I. G. Rutshtein 《Ore Geology Reviews》2001,17(4):1102

It is proposed that there are three types of gold deposits in Eastern and Central Transbaikalia (Trans-Baikal province), namely: (i) high-sulphide intrusion-related deposits with some signs of porphyry deposits, (ii) low-sulphide intrusion-related deposits, and (iii) low-sulphide epithermal Au–Ag deposits. Most of the gold deposits belong to the first two types, and their ages are Middle–Late Jurassic. Deposits of the third type are not numerous, and their age is Early Cretaceous.The majority of the gold mineralization is spatially related to the two branches of the Mongolia–Okhotsk suture, along which Siberia collided, at the Early/Middle Jurassic boundary, with the Mongolia–North China continent and the Onon island-arc terrane located between the two continents. Collision-related thrusting, folding and magmatism lasted until the latest Jurassic, when they gave way to post-collisional rifting that continued until the end of Early Cretaceous.According to their age, relation to magmatism and tectonic framework, the intrusion-related deposits (high- and low-sulphide) were formed in a regional collisional setting. Extensional environments at that time existed only in local areas in the roofs of great magmatic chambers. Low-sulphide epithermal deposits were formed during Early Cretaceous post-collisional rifting.  相似文献   

Detection of Breathing and Heartbeat Through Snow Using a Microwave Transceiver     

Pieraccini  M. Luzi  G. Dei  D. Pieri  L. Atzeni  C. 《Geoscience and Remote Sensing Letters, IEEE》2008,5(1):57-59

The potential of a continuous-wave microwave transceiver as a tool for detecting breathing and heartbeat of people buried in snow has been experimentally evaluated. The breathing has been clearly detected through a 1.8-m-thick snow barrier as well as through the 1.2-m-thick roof of an igloo dugout to simulate the experimental conditions of a human being trapped under an avalanche.  相似文献   

Chemical characteristics of atmospheric bulk deposition in a semi-rural area of the <Emphasis Type="Bold">Po Valley</Emphasis> (Italy)     

Laura?Tositti  Linda?Pieri  Erika?BrattichEmail authorView author&#;s OrcID profile  Silvia?Parmeggiani  Francesca?Ventura 《Journal of Atmospheric Chemistry》2018,75(1):97-121

This study provides an analysis of a five-year time series chemical composition of the bulk deposition (2009–2013), collected within a farm surrounded by industrial and urban settlements in a semi-rural area of the Po Valley, with the aim of characterizing potential emission sources affecting precipitation composition at the site. Most monitoring efforts in this region, recognized as one of the most polluted in the world both due to the intense industrialisation and urbanisation as well as to frequent air stagnation conditions, are presently devoted more to gaseous and particulate pollutants than to precipitation chemistry. The bulk deposition samples were very concentrated in chemical species, both acidic and alkaline, high compared to other polluted sites in the world and to locations in the same district. The mean ions concentrations (in μeq l^?1) are: NO₃ ^? (243) > SO₄ ^2? (220) > PO₄ ^3? (176) > Cl^? (153) > NO₂ ^? (29) > F^? (2.6); NH₄ ⁺ (504) > Ca²⁺ (489) > K⁺ (151) > Na⁺ (127) > Mg²⁺ (127). pH data shows a trend toward slightly alkaline conditions attributed to the large presence of ammonium and crustal elements, in spite of high concentrations of nitrates and sulphates. The relevant concentrations of Ca²⁺ and Mg²⁺ further suggests that these alkaline conditions might be due to the correspondingly significant concentrations of carbonates/bicarbonates in our dataset. While back-trajectories analysis suggests the stronger importance of local resuspension over long-range transport, statistical analyses on ion composition highlight the key role exerted by agricultural activity, especially in the case of NH₄ ⁺, K⁺, Ca²⁺ and PO₄ ^3? (especially linked to fertilisation practices and soil resuspension due to mechanical operations). Apart from Na⁺ and Cl^? ions which correlate well as expected, indicating their likely common origin from marine salt, the identification of the origin of the other ions is very complex due to the contribution of diverse local sources, such as industrial and residential settlements.  相似文献   

The reflection spectrum of liquid sulfur: Implications for Io     

Robert M. Nelson  David C. Pieri  Stephen M. Baloga  Douglas B. Nash  Carl Sagan 《Icarus》1983,56(3):409-413

The spectral reflectance from 0.38 to 0.75 μm of a column of liquid sulfur has been measured at several temperatures between the melting point (～118°C) and 173°C. Below 160°C the spectral reflectance was observed to vary reversibly as a function of temperature, independent of the previous thermal history of the column. Once the temperature exceeded 160°C, the spectrum would not change given a subsequent decrease in temperature. The spectral reflectance of the liquid-sulfur column at all temperatures was very low (10–19%). Combining this information with Voyager spectrophotometry of Jupiter's satellite Io, it is concluded that liquid sulfur at any temperature on Io's surface would be classified as a “black area” according to the standards used by the Voyager imaging team in their spectrophotometric analysis (L. Soderblom, T. V. Johnson, D. Morrison, E. Danielson, B. L. Smith, J. Veverka, A. Cook, C. Sagan, P. Kupferman, D. Pieri, J. Mosher, C. Avis, J. Gradie, and T. Clancy (1980). Geophys. Res. Lett.7, 963–966).  相似文献   

Sedimentation Patterns of Photosynthetic Bacteria Based on Pigment Markers in Meromictic Lake La Cruz (Spain): Paleolimnological Implications     

Lidia Romero  Antonio Camacho  Eduardo Vicente  Maria R. Miracle 《Journal of Paleolimnology》2006,35(1):167-177

Sedimentation fluxes of photosynthetic pigments and their derivatives, focused on the anoxygenic bacteria populations, were determined in meromictic Lake La Cruz over a three-year period using sediment traps. Bacterial settling occurs in pulses in response to lake dynamics. Two main annual events affect particle settling in Lake La Cruz: (1) Following an event of massive calcium precipitation in summer that caused water whiting, a maximum flux of chlorophyll a and derivatives towards the sediment was registered. Although whiting is accompanied by massive phytoplankton biomass sinking, it was not followed by concomitant photosynthetic bacterial sinking. (2) In contrast, the disruption of the chemocline and the contact of bacterial populations with oxygenated waters during autumn overturn provoked a destruction of the sulfur bacterial plate, causing mass mortality, registered in the settling material as photosynthetic pigments and their derivatives from phototrophic bacteria. Among the bacteriochlorophyll a oxidation products, bacterioviridin (bvir) was detected in high relative abundance in the settled material collected by sediment traps. The much increased flux of bvir after thermal overturn, associated with mass mortality of the purple sulfur bacterium, Amoebobacter purpureus, confirms the suitability of this molecule as a useful paleoindicator of the degree of oxygen exposure experienced by the purple sulfur bacteria population.  相似文献   

Evaluation of the WEPP model and digital elevation grid size,for simulation of streamflow and sediment yield in a heterogeneous catchment          下载免费PDF全文

Linda Pieri  Matteo Poggio  Marco Vignudelli  Marco Bittelli 《地球表面变化过程与地形》2014,39(10):1331-1344

The paper presents the result of an application of the GeoWEPP model in a heterogeneous semi‐agricultural catchment located in the northern Italian Apennines mountain range. The objectives were: (a) to evaluate the GeoWEPP model in a heterogeneous catchment in a Mediterranean climate and (b) to examine the effect of digital elevation model grid size on hydrological and sediment yield simulations. The catchment is characterized by large heterogeneity in geology, soil type, vegetation cover and topography. In addition, 10% of its area is occupied by calanchi (badlands), characterized by steep, bare soil and accentuated erosion. Experimental streamflow data were compared with those simulated by GeoWEPP for a period of eight years and the results were evaluated by means of statistical indices, with the analysis of the flow duration curve. Simulated sediment yields were compared with experimental data for one year. The streamflow cumulative annual results were satisfactory with NSE oscillating between 0.40 and 0.83 and RMSE between 1.1 and 2.9 mm. Also, the performance of the model with daily streamflow data was positive (NSE = 0.68 and RMSE = 1.9 mm). The flow duration curve indicated that GeoWEPP could represent the experimental streamflow for fluxes over 1 mm d^?1. The model performance for simulation of sediment yield was satisfactory with both digital elevation models of different grid sizes (NSE = 0.84 and 0.87). Indeed, the sensitivity analysis tests of the model showed that there was no statistically significant improvement in the accuracy of the digital elevation model between 10 and 2 m resolution. These results were confirmed for both streamflow as well as sediment yield. Additional sensitivity analysis of other model parameters performed on the entire catchment and badlands hillslopes showed that bedrock hydraulic conductivity primarily affected the model in both settings. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Partial amorphization of experimentally shocked plagioclase: A spectroscopic study     

Lidia Pittarello  Joerg Fritz  Julia Roszjar  Christoph Lenz  Chutimun Chanmuang N.  Christian Koeberl 《Meteoritics & planetary science》2020,55(3):669-678

Shock amorphization of plagioclase, from partial to complete, has been used to evaluate the degree of shock in meteorites. Important information on the shock amplitude can be derived from the measurement of the refractive index in plagioclase, either from mineral separates or in petrographic thin sections. However, this technique is time‐consuming, and associated sample preparations are considered destructive and are not always possible for precious and rare meteorite samples. In addition, plagioclase amorphization is commonly inhomogeneous at the sample scale and a statistically meaningful number of grains must be considered. Here, we apply several nondestructive spectroscopic techniques, such as Raman spectroscopy, photoluminescence, and cathodoluminescence, to plagioclase experimentally shocked at 28 GPa, and thus in the transition regime between crystalline plagioclase and fully amorphous material. Most of the plagioclase was transformed into diaplectic glass at 28 GPa, yet some grains exhibit heterogeneously distributed crystalline domains. This confirms that intrinsic and extrinsic factors lead to local variations in the intensity of the shock pressure within individual plagioclase crystals of homogeneous composition. The amorphization of plagioclase can qualitatively (and potentially also quantitatively) be investigated by spectroscopic techniques, highlighting such local variations in the shock efficiency.  相似文献   

Shock metamorphism in plagioclase and selective amorphization     

Lidia Pittarello  Luke Daly  Annemarie E. PickersgilL  Ludovic Ferrire  Martin R. Lee 《Meteoritics & planetary science》2020,55(5):1103-1115

Plagioclase feldspar is one of the most common rock‐forming minerals on the surfaces of the Earth and other terrestrial planetary bodies, where it has been exposed to the ubiquitous process of hypervelocity impact. However, the response of plagioclase to shock metamorphism remains poorly understood. In particular, constraining the initiation and progression of shock‐induced amorphization in plagioclase (i.e., conversion to diaplectic glass) would improve our knowledge of how shock progressively deforms plagioclase. In turn, this information would enable plagioclase to be used to evaluate the shock stage of meteorites and terrestrial impactites, whenever they lack traditionally used shock indicator minerals, such as olivine and quartz. Here, we report on an electron backscatter diffraction (EBSD) study of shocked plagioclase grains in a metagranite shatter cone from the central uplift of the Manicouagan impact structure, Canada. Our study suggests that, in plagioclase, shock amorphization is initially localized either within pre‐existing twins or along lamellae, with similar characteristics to planar deformation features (PDFs) but that resemble twins in their periodicity. These lamellae likely represent specific crystallographic planes that undergo preferential structural failure under shock conditions. The orientation of preexisting twin sets that are preferentially amorphized and that of amorphous lamellae is likely favorable with respect to scattering of the local shock wave and corresponds to the “weakest” orientation for a specific shock pressure value. This observation supports a universal formation mechanism for PDFs in silicate minerals.  相似文献   

Václav Bumba (1925 – 2018)     

Pavel Kotrč  Petr Heinzel  Michal Sobotka  Pavel Ambrož  Lidia van Driel-Gesztelyi 《Solar physics》2018,293(3):40

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