Evaluation and Assessment of Blast-Induced Ground Vibrations in an Underground Gold Mine: A Case Study     

Tribe  Jarryd  Koroznikova  Larissa  Khandelwal  Manoj  Giri  Jason 《Natural Resources Research》2021,30(6):4673-4694

Natural Resources Research - Ground vibrations induced during rock fragmentation by blasting remain a potential source of hazard for the stability of nearby structures. In this paper, to forecast...  相似文献   

Stormy geomorphology: geomorphic contributions in an age of climate extremes          下载免费PDF全文

Larissa A. Naylor  Tom Spencer  Stuart N. Lane  Stephen E. Darby  Francis J. Magilligan  Mark G. Macklin  Iris Möller 《地球表面变化过程与地形》2017,42(1):166-190

The increasing frequency and/or severity of extreme climate events are becoming increasingly apparent over multi‐decadal timescales at the global scale, albeit with relatively low scientific confidence. At the regional scale, scientific confidence in the future trends of extreme event likelihood is stronger, although the trends are spatially variable. Confidence in these extreme climate risks is muddied by the confounding effects of internal landscape system dynamics and external forcing factors such as changes in land use and river and coastal engineering. Geomorphology is a critical discipline in disentangling climate change impacts from other controlling factors, thereby contributing to debates over societal adaptation to extreme events. We review four main geomorphic contributions to flood and storm science. First, we show how palaeogeomorphological and current process studies can extend the historical flood record while also unraveling the complex interactions between internal geomorphic dynamics, human impacts and changes in climate regimes. A key outcome will be improved quantification of flood probabilities and the hazard dimension of flood risk. Second, we present evidence showing how antecedent geomorphological and climate parameters can alter the risk and magnitude of landscape change caused by extreme events. Third, we show that geomorphic processes can both mediate and increase the geomorphological impacts of extreme events, influencing societal risk. Fourthly, we show the potential of managing flood and storm risk through the geomorphic system, both near‐term (next 50 years) and longer‐term. We recommend that key methods of managing flooding and erosion will be more effective if risk assessments include palaeodata, if geomorphological science is used to underpin nature‐based management approaches, and if land‐use management addresses changes in geomorphic process regimes that extreme events can trigger. We argue that adopting geomorphologically‐grounded adaptation strategies will enable society to develop more resilient, less vulnerable socio‐geomorphological systems fit for an age of climate extremes. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Distribution and population structure of the fish Helicolenus dactylopterus dactylopterus (Delaroche, 1809) in the Central Mediterranean (Southern Tyrrhenian Sea)     

Laura Pirrera  Teresa Bottari  Barbara Busalacchi  Daniela Giordano  Larissa Modica  Anna Perdichizzi  Francesco Perdichizzi  Adriana Profeta  & Paola Rinelli 《Marine Ecology》2009,30(S1):161-174

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Geochemistry of orthogneisses and metasedimentary rocks across a proposed terrane boundary in the Central Domain of Borborema Province,NE Brazil: Geodynamic implications     

Sérgio P. Neves  Vanja Coelho Alcantara 《Journal of South American Earth Sciences》2010,29(2):498-511

The Borborema Province, northeastern Brazil, occupies a central position in pre-drift reconstructions of western Gondwana, making an understanding of its geological evolution crucial for Neoproterozoic reconstructions. In recent years, it has been proposed that the Borborema Province grew by accretion of distinct tectonic terranes. In order to test this hypothesis, we compare here the geochemistry of orthogneisses and metasedimentary rocks across a proposed terrane boundary in the Central Domain of the province. Orthogneiss samples show smooth trends in Harker diagrams and similar rare earth element (REE) patterns, characterized by sharp decreases from La to Sm (chondrite-normalized La/Sm = 3–6) and flat heavy REE profiles (chondrite-normalized Tb/Yb = 1.5–2.5), with small or no Eu anomalies. In primitive mantle-normalized multi-element diagrams, all samples show parallel patterns characterized by sharp negative anomalies of U, Ta, Nb, P and Ti. The metasedimentary samples show little scatter of the major elements in Harker diagrams, suggesting that their chemistry was little affected by post-depositional diagenesis and metamorphism. They have indistinguishable chondrite-normalized REE patterns, characterized by light REE enrichment, flat heavy REE (normalized Tb/Y = 1–2) and small or no negative Eu anomalies, and similar ratios of immobile trace elements (e.g., Th/Sc, Zr/Sc). The geochemistry of the metasedimentary samples is comparable in many ways to those of the orthogneisses, suggesting that these may have been an important source of the precursor sedimentary rocks. These data do not support the terrane accretion hypothesis, rather suggesting the existence of a continuous basement that became available for erosion during intraplate continental extension in the late Neoproterozoic. Comparisons of the studied sequences with those present in the Northern Domain suggest that most, if not all of the Neoproterozoic geodynamic evolution of Borborema Province, occurred in an intracontinental setting.  相似文献   

Changing sea ice conditions and marine transportation activity in Canadian Arctic waters between 1990 and 2012   总被引：2，自引：0，他引：2  

Larissa Pizzolato  Stephen E. L. Howell  Chris Derksen  Jackie Dawson  Luke Copland 《Climatic change》2014,123(2):161-173

Declining sea ice area in the Canadian Arctic has gained significant attention with respect to the prospect of increased shipping activities. To investigate relationships between recent declines in sea ice area with Arctic maritime activity, trend and correlation analysis was performed on sea ice area data for total, first-year ice (FYI), and multi-year ice (MYI), and on a comprehensive shipping dataset of observed vessel transits through the Vessel Traffic Reporting Arctic Canada Traffic Zone (NORDREG zone) from 1990 to 2012. Links to surface air temperature (SAT) and the satellite derived melt season length were also investigated. Between 1990 and 2012, statistically significant increases in vessel traffic were observed within the NORDREG zone on monthly and annual time-scales coincident with declines in sea ice area (FYI, MYI, and total ice) during the shipping season and on a monthly basis. Similarly, the NORDREG zone is experiencing increased shoulder season shipping activity, alongside an increasing melt season length and warming surface air temperatures (SAT). Despite these trends, only weak correlations between the variables were identified, although a step increase in shipping activity is apparent following the former summer sea ice extent minimum in 2007. Other non-environmental factors have also likely contributed to the observed increase in Arctic shipping activity within the Canadian Arctic, such as tourism demand, community re-supply needs, and resource exploration trends.  相似文献   

Anthropogenic organic contaminants in water, sediments and benthic organisms of the mangrove-fringed Segara Anakan Lagoon, Java, Indonesia   总被引：1，自引：0，他引：1  

Dsikowitzky L  Nordhaus I  Jennerjahn TC  Khrycheva P  Sivatharshan Y  Yuwono E  Schwarzbauer J 《Marine pollution bulletin》2011,62(4):851-80

Segara Anakan, a mangrove-fringed coastal lagoon in Indonesia, has a high diversity of macrobenthic invertebrates and is increasingly affected by human activities. We found >50 organic contaminants in water, sediment and macrobenthic invertebrates from the lagoon most of which were polycyclic aromatic compounds (PACs). Composition of PACs pointed to petrogenic contamination in the eastern lagoon. PACs mainly consisted of alkylated PAHs, which are more abundant in crude oil than parent PAHs. Highest total PAC concentration in sediment was above reported toxicity thresholds for aquatic invertebrates. Other identified compounds derived from municipal sewage and also included novel contaminants like triphenylphosphine oxide. Numbers of stored contaminants varied between species which is probably related to differences in microhabitat and feeding mode. Most contaminants were detected in Telescopium telescopium and Polymesoda erosa. Our findings suggest that more attention should be paid to the risk potential of alkylated PAHs, which has hardly been addressed previously.  相似文献   

Swirls on the Moon and Mercury: meteoroid swarm encounters as a formation mechanism     

Larissa V. Starukhina  Yuriy G. Shkuratov 《Icarus》2004,167(1):136-147

We show that plowing of the lunar and mercurian regoliths by dense meteoroid swarms (the remnants of degassed comet nuclei) can be considered as the most probable mechanism of swirl formation. Frequently discussed mechanical and thermal effects of coma gas in cometary encounters with the Moon or Mercury are shown to be negligible as compared to those of the impact of a compact cometary nucleus. The result of such an impact does not differ substantially from that of denser impactors, so impacts of comets with compact nuclei can hardly be the mechanism of swirl formation. On the other hand, the projectile swarm consisting of numerous fragments of previously disrupted cometary nucleus produces many small craters and ejecta in a large area. The particles of the ejecta go through numerous collisions with each other. This may result in formation of the characteristic swirl pattern and dust component of the regolith. This can also decrease surface micro-roughness, which is consistent with photometric observations. Regolith plowing to depths up to a few meters excavates the immature regolith to the surface but cannot noticeably change the initial chemical composition of the upper layers in the area of swarm fall. This is generally in agreement with the results obtained from Clementine spectral data. Swirls are expected to be more numerous on Mercury due to more frequent swarm encounters and more dense clouds of debris in the vicinity of the Sun.  相似文献   

Precipitation of pyroxenes and Mg₂SiO₄ from majoritic garnet: simulation of peridotite exhumation from great depth     

Larissa F. Dobrzhinetskaya  Harry W. Green  II  Alex P. Renfro  Krassimir N. Bozhilov  Dirk Spengler  Herman L. M. van Roermund 《地学学报》2004,16(6):325-330

Our experimental simulations of the exhumation path of mantle peridotites show that high‐temperature (1400 °C) decompression of lherzolite from 14 to 13 and 12 GPa results in exsolution of interstitial blebs of diopside and Mg₂SiO₄ (wadsleyite) lamellae from majoritic garnet. At lower pressures (from 8 to 5 GPa, at T = 1400 °C) only enstatite exsolves as blebs at garnet boundaries. Continuous high‐temperature decompression from 14 to 7 GPa produces zoned majoritic garnet containing blebs of exsolved pyroxenes inside garnet rims. No intracrystalline precipitation of pyroxene was observed in garnet, although such lamellae are found in some natural garnet peridotites. The explanation appears to be the three orders of magnitude difference in grain size between experimental and natural specimens. Our data suggest that Mg₂SiO₄ and diopside exsolutions reflect the deepest point of the exhumation path of garnet peridotites, whereas enstatite precipitation may be restricted to garnets with less majoritic component at shallower depths.  相似文献   

Intergranular diamonds derived from partial melting of crustal rocks at ultrahigh-pressure metamorphic conditions     

Andrey V. Korsakov  Karel Theunissen  Larissa V. Smirnova 《地学学报》2004,16(3):146-151

By reporting for the first time intergranular diamond in quartz–feldspar (Qtz–Kfs) aggregates, the processes of metamorphic diamond formation have to be reconsidered. Based on their Kfs/Qtz ratio, the texture of these aggregates are proposed to result from ‘granitic’ melt with a calculated composition that corresponds well with that of experimental data for the pelitic system. Taking into account experiments on CO₂ solubility in silicate melt under ultrahigh‐pressure conditions, a granitic melt is further suggested to act as a crystallization medium as well as a transport medium for producing metamorphic diamond.  相似文献   

The influence of geological factors on radon risk in groundwater and dwellings in the region of Amarante (Northern Portugal)     

L. M. O. Martins  M. E. P. Gomes  L. J. P. F. Neves  A. J. S. C. Pereira 《Environmental Earth Sciences》2013,68(3):733-740

The region of Amarante (Northern Portugal) is composed of Hercynian tardi-tectonics granites and Paleozoic metasediments. Petrographic observations and SEM studies show that uranium is mainly contained within the rock in heavy accessory minerals such as apatite, zircon, monazite, uraninite, thorite and thorianite. The geological, geochemical and radiological data obtained suggest that the radon concentrations in dwellings of the studied area are mainly related with the uranium content of the rocks. Indeed, the highest contents were observed in granite AT2 of Padronelo (18.2 ppm) and the granite AT1 of Telões (10.3 ppm), with metasediments showing much lower uranium contents of 1.6 ppm; radon concentrations were evaluated in dwellings, using CR-39 passive detectors, and the results obtained in winter conditions suggest that the most productive geological units are the granites AT2 and AT1, with geometric means of 430 and 220 Bq/m³, respectively, while the metasediments show the lowest value of 85 Bq/m³. Some moderate radiometric anomalies, where uranium contents can double typical background values, were found in relation with specific fault systems of the region affecting granitic rocks, thus increasing radon risk; this is an indication of uranium mobility, likely resulting from the leaching of primary mineral supports as uraninite. Groundwater radionuclide contents show a wide range of results, with the highest activities related with granitic lithologies: 2,295 Bq/l for radon, 0.83 Bq/l for gross α and 0.71 Bq/l for gross β, presenting metasediments much lower values, in good agreement with other results obtained. Absorbed dose measured with gamma spectrometers in direct contact with the rocks is directly related with the uranium contents of the rocks, and thus works as a fast proxy for radon risk. It is concluded that radon risk is moderate to high in the granitic areas of the Amarante region and low in the metasediments of the same region.  相似文献