Effects of limestone petrography and calcite microstructure on OPC clinker raw meals burnability     

Galimberti  Matteo  Marinoni  Nicoletta  Della Porta  Giovanna  Marchi  Maurizio  Dapiaggi  Monica 《Mineralogy and Petrology》2017,111(5):793-806

Mineralogy and Petrology - Limestone represents the main raw material for ordinary Portland cement clinker production. In this study eight natural limestones from different geological environments...  相似文献   

Comparative analysis of phytoplankton patterns in two modified lakes with contrasting hydrological features   总被引：1，自引：0，他引：1  

Monica Tolotti  Adriano Boscaini  Nico Salmaso 《Aquatic Sciences - Research Across Boundaries》2010,72(2):213-226

Hydrological management represents one of the main factors controlling physical and chemical characteristics as well as biodiversity and productivity of planktonic communities in artificial and modified lakes. In Alpine piedmont reservoirs, which often receive large water inputs from high altitude watersheds, control operated by hydrological regime over ecological processes is also mediated by other related variables such as water temperature and turbulence, and load of inorganic suspended solids. This contribution reports on results obtained from a comparative study on the impact of hydrological regime on phytoplankton patterns in two modified piedmont lakes of different size and hydrology located in the NE Italian Alps: Lake Santa Croce (V = 147 × 10⁶ km³) and Lake Toblino (V = 5.7 × 10⁶ km³). Phytoplankton of both lakes was characterised by a pronounced dominance of diatoms, accompanied by cryptophytes and green algae. The mesotrophic Lake Santa Croce showed a typical seasonal succession of dominant groups, while phytoplankton growth in the eutrophic Lake Toblino was variable and showed pronounced pulses in relation to dramatic changes in the hydrological regime. The comparative study of phytoplankton, based on morpho-functional classification and application of multivariate analyses (non-metric multidimensional scaling, principal components analysis, and redundancy analysis), showed that hydrological regime affected phytoplankton growth in the two lakes both directly, i.e. through renewal time, and indirectly, i.e. regulating thermal conditions in Lake Santa Croce and nutrient availability in both lakes. Nevertheless, effectiveness of hydrological constraints largely depended on lake size and morphology, being more pronounced in the shallower and smaller Lake Toblino.  相似文献   

The SHARE European Earthquake Catalogue (SHEEC) 1000–1899     

M. Stucchi  A. Rovida  A. A. Gomez Capera  P. Alexandre  T. Camelbeeck  M. B. Demircioglu  P. Gasperini  V. Kouskouna  R. M. W. Musson  M. Radulian  K. Sesetyan  S. Vilanova  D. Baumont  H. Bungum  D. Fäh  W. Lenhardt  K. Makropoulos  J. M. Martinez Solares  O. Scotti  M. Živčić  P. Albini  J. Batllo  C. Papaioannou  R. Tatevossian  M. Locati  C. Meletti  D. Viganò  D. Giardini 《Journal of Seismology》2013,17(2):523-544

In the frame of the European Commission project “Seismic Hazard Harmonization in Europe” (SHARE), aiming at harmonizing seismic hazard at a European scale, the compilation of a homogeneous, European parametric earthquake catalogue was planned. The goal was to be achieved by considering the most updated historical dataset and assessing homogenous magnitudes, with support from several institutions. This paper describes the SHARE European Earthquake Catalogue (SHEEC), which covers the time window 1000–1899. It strongly relies on the experience of the European Commission project “Network of Research Infrastructures for European Seismology” (NERIES), a module of which was dedicated to create the European “Archive of Historical Earthquake Data” (AHEAD) and to establish methodologies to homogenously derive earthquake parameters from macroseismic data. AHEAD has supplied the final earthquake list, obtained after sorting duplications out and eliminating many fake events; in addition, it supplied the most updated historical dataset. Macroseismic data points (MDPs) provided by AHEAD have been processed with updated, repeatable procedures, regionally calibrated against a set of recent, instrumental earthquakes, to obtain earthquake parameters. From the same data, a set of epicentral intensity-to-magnitude relations has been derived, with the aim of providing another set of homogeneous Mw estimates. Then, a strategy focussed on maximizing the homogeneity of the final epicentral location and Mw, has been adopted. Special care has been devoted also to supply location and Mw uncertainty. The paper focuses on the procedure adopted for the compilation of SHEEC and briefly comments on the achieved results.  相似文献   

Sub-Gaussian model of processes with heavy-tailed distributions applied to air permeabilities of fractured tuff     

Monica Riva  Shlomo P. Neuman  Alberto Guadagnini 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(1):195-207

Earth and environmental variables are commonly taken to have multivariate Gaussian or heavy-tailed distributions in space and/or time. This is based on the observation that univariate frequency distributions of corresponding samples appear to be Gaussian or heavy-tailed. Of particular interest to us is the well-documented but heretofore little noticed and unexplained phenomenon that whereas the frequency distribution of log permeability data often seems to be Gaussian, that of corresponding increments tends to exhibit heavy tails. The tails decay as powers of ? $ \alpha $ where 1 <  $ \alpha $  < 2 is either constant or grows monotonically toward an asymptote with increasing separation distance or lag. We illustrate the latter phenomenon on 1-m scale log air permeabilities from pneumatic tests in 6 vertical and inclined boreholes completed in unsaturated fractured tuff near Superior, Arizona. We then show theoretically and demonstrate numerically, on synthetically generated signals, that whereas the case of constant $ \alpha $ is consistent with a collection of samples from truncated sub-Gaussian fractional Lévy noise, a random field (or process) subordinated to truncated fractional Gaussian noise, the case of variable $ \alpha $ is consistent with a collection of samples from truncated sub-Gaussian fractional Lévy motion (tfLm), a random field subordinated to truncated fractional Brownian motion. Whereas the first type of signal is relatively regular and characterized by Lévy index $ \alpha $ , the second is highly irregular (punctuated by spurious spikes) and characterized by the asymptote of $ \alpha $ values associated with its increments. We describe a procedure to estimate the parameters of univariate distributions characterizing such signals and apply it to our log air permeability data. The latter are found to be consistent with a collection of samples from tfLm with $ \alpha $ slightly smaller than 2, which is easily confused with a Gaussian field (characterized by constant $ \alpha $  = 2). The irregular (spiky) nature of this signal is typical of observed fractured rock properties. We propose that distributions of earth and environmental variable be inferred jointly from measured values and their increments in a way that insures consistency between these two sets of data.  相似文献   

Geodynamic evolution of a forearc rift in the southernmost Mariana Arc     

Julia M. Ribeiro  Robert J. Stern  Fernando Martinez  Osamu Ishizuka  Susan G. Merle  Katherine Kelley  Elizabeth Y. Anthony  Minghua Ren  Yasuhiko Ohara  Mark Reagan  Guillaume Girard  Sherman Bloomer 《Island Arc》2013,22(4):453-476

The southernmost Mariana forearc stretched to accommodate opening of the Mariana Trough backarc basin in late Neogene time, erupting basalts at 3.7–2.7 Ma that are now exposed in the Southeast Mariana Forearc Rift (SEMFR). Today, SEMFR is a broad zone of extension that formed on hydrated, forearc lithosphere and overlies the shallow subducting slab (slab depth ≤ 30–50 km). It comprises NW–SE trending subparallel deeps, 3–16 km wide, that can be traced ≥ ∼30 km from the trench almost to the backarc spreading center, the Malaguana‐Gadao Ridge (MGR). While forearcs are usually underlain by serpentinized harzburgites too cold to melt, SEMFR crust is mostly composed of Pliocene, low‐K basaltic to basaltic andesite lavas that are compositionally similar to arc lavas and backarc basin (BAB) lavas, and thus defines a forearc region that recently witnessed abundant igneous activity in the form of seafloor spreading. SEMFR igneous rocks have low Na₈, Ti₈, and Fe₈, consistent with extensive melting, at ∼23 ± 6.6 km depth and 1239 ± 40°C, by adiabatic decompression of depleted asthenospheric mantle metasomatized by slab‐derived fluids. Stretching of pre‐existing forearc lithosphere allowed BAB‐like mantle to flow along the SEMFR and melt, forming new oceanic crust. Melts interacted with pre‐existing forearc lithosphere during ascent. The SEMFR is no longer magmatically active and post‐magmatic tectonic activity dominates the rift.  相似文献   

Untangling the influence of in-lake productivity and terrestrial organic matter flux on 4,250 years of mercury accumulation in Lake Hambre, Southern Chile     

Yvonne-Marie Hermanns  Antonio Martinez Cortizas  Helge Arz  Rüdiger Stein  Harald Biester 《Journal of Paleolimnology》2013,49(4):563-573

There is ongoing debate about the relative influence of aquatic production, flux, and sedimentation of aquatic and terrestrial organic matter on mercury accumulation in lake sediments. In this study, lake sediments spanning the past 4,250 years, were collected from remote, organic-rich Lake Hambre, Patagonia (53° S) and investigated for changes in the accumulation of pre-anthropogenic mercury and organic matter of aquatic and terrestrial origin. Natural mercury accumulation varied by up to a factor of four, comparable to the recent anthropogenic forcing of the mercury cycle (factor 3–5). Hydrogen and Oxygen indices (HI and OI, Rock–Eval©) and nitrogen/carbon ratios of the organic matter, combined with multi-element sediment data, reveal intense changes in aquatic productivity as well as influx of terrestrial organic matter into the lake. Evaluation of the multi-element dataset using Principal Component Analysis shows clear covariation of mercury with other soil-derived elements such as copper and yttrium. This covariance reflects a common transport mechanism, i.e. leaching of trace-element-bearing organic matter complexes from catchment soils. Correlation between changes in aquatic productivity and mercury concentrations occurs in some sections of the record, but we do not suggest they are linked by a direct causal relationship. Mass balance approaches suggest that mercury scavenging and accumulation in this organic-rich lake is controlled by the supply of mercury from catchment soils rather than the amount of organic material produced within the water column. A common controlling mechanism, i.e. changing climate, however, is thought to independently drive variations in both the flux of terrestrial organic matter mercury complexes and aquatic productivity.  相似文献   

Severe tornadoes on the Caribbean coast of Colombia since 2001 and their relation to local climate conditions     

J. C. Ortiz-Royero  Monica Rosales 《Natural Hazards》2012,64(2):1805-1821

Tornadoes have been reported in various places around the world. The United States has the greatest number of tornado reports. In South America, tornadoes have been reported in Argentina and neighboring countries, such as Chile, Brazil, and Uruguay. There are no reports of tornadoes in Colombia in the worldwide databases. The first reported tornado event in Colombia took place in 2001. Since then, four tornados have affected the northern part of Colombia. The aim of this study is to characterize the events reported on the Caribbean coast of Colombia and their relation to local climate conditions. Before 2001, we had no knowledge regarding tornadoes in this area. However, during the past 10?years, these atmospheric phenomena have occurred in Barranquilla and the surrounding metropolitan area. Worldwide databases on tornadoes have not registered any such events in this part of South America. A review of the atmospheric information was conducted to determine the influence of air temperature increases on tornado formation. This study reveals that tornadoes have appeared between May and September, the months during which the city experiences the hottest temperatures of the year. The most significant tornado took place on September 15, 2006. This tornado lasted 15?min and travelled almost 10?km. Of the four registered tornadoes, this was the only one to affect the residential area of the city. The other three affected only the suburbs located in the surrounding metropolitan area. The most recent phenomenon related with tornadoes took place between July and August of 2010, during which three tornadoes could have potentially formed. However, a vortex never made contact with the ground. This meteorological analysis is very basic because climate information for these areas is limited. Still, what information we have reveals conditions that are typical of tornado formation: a mass of cold air combined with high air temperatures in a specific area. The data analysis reveals that tornados have occurred between May and June. These months correspond to the period characterized by the highest temperatures: average temperatures of 28.2?°C and maximum temperatures of 33.2?°C. This is also the period characterized by the greatest relative humidity and precipitation (84?% and 50?mm, respectively). Because the tornadoes reports only appeared in the last 10?years, it is not possible to determine whether there is a realistic relationship between their occurrence and large-scale climatic change. This article characterizes tornadoes as a new environmental threat and not an isolated phenomenon for this part of Colombia. Tornadoes in this region should thus be included in global databases.  相似文献   

An HWRF-based ensemble assessment of the land surface feedback on the post-landfall intensification of Tropical Storm Fay (2008)     

Monica Laureano Bozeman  Dev Niyogi  S. Gopalakrishnan  Frank D. Marks Jr.  Xuejin Zhang  Vijay Tallapragada 《Natural Hazards》2012,63(3):1543-1571

While tropical cyclones (TCs) usually decay after landfall, Tropical Storm Fay (2008) initially developed a storm central eye over South Florida by anomalous intensification overland. Unique to the Florida peninsula are Lake Okeechobee and the Everglades, which may have provided a surface feedback as the TC tracked near these features around the time of peak intensity. Analysis is done with the use of an ensemble model-based approach with the Developmental Testbed Center (DTC) version of the Hurricane WRF (HWRF) model using an outer domain and a storm-centered moving nest with 27- and 9-km grid spacing, respectively. Choice of land surface parameterization and small-scale surface features may influence TC structure, dictate the rate of TC decay, and even the anomalous intensification after landfall in model experiments. Results indicate that the HWRF model track and intensity forecasts are sensitive to three features in the model framework: land surface parameterization, initial boundary conditions, and the choice of planetary boundary layer (PBL) scheme. Land surface parameterizations such as the Geophysical Fluid Dynamics Laboratory (GFDL) Slab and Noah land surface models (LSMs) dominate the changes in storm track, while initial conditions and PBL schemes cause the largest changes in the TC intensity overland. Land surface heterogeneity in Florida from removing surface features in model simulations shows a small role in the forecast intensity change with no substantial alterations to TC track.  相似文献   

A new mammalian fauna from the earliest Eocene (Ilerdian) of the Corbières (Southern France): palaeobiogeographical implications     

Bernard Marandat  Sylvain Adnet  Laurent Marivaux  Alain Martinez  Monique Vianey-Liaud  Rodolphe Tabuce 《Swiss Journal of Geoscience》2012,105(3):417-434

A new mammal fauna from the earliest Eocene of Le Clot (Corbières, Southern France) is described. Some taxa identified there, such as Corbarimys hottingeri and Paschatherium plaziati, allow a correlation with the previously described Corbières fauna of Fordones. Moreover, the presence at Le Clot of Lessnessina praecipuus, which is defined in Palette (Provence, Southern France) allows correlating both localities. All three of these localities are referred to the MP7 reference level, even if a direct correlation with the type locality of MP7 (Dormaal, Belgium) is not ascertained. A Southern Europe biochronological sequence is proposed for the beginning of the Eocene: Silveirinha, Fordones/Palette/Le Clot, Rians/Fournes. The diagnosis of a new species of a neoplagiaulacid multituberculate (?Ectypodus riansensis nov. sp.) is proposed. From a compilation of data concerning the earliest Eocene faunas from both Northern Europe and Southern Europe, we conclude that two faunas corresponding to two distinct palaeobiogeographical provinces existed in Western Europe. This faunal disparity, probably related to climatic differences, makes correlations particularly difficult between the two provinces.  相似文献   

Application of portable X-ray fluorescence analyses to metabasalt stratigraphy,Plutonic Gold Mine,Western Australia     

Michael F. Gazley  Julie K. Vry  Ettienne du Plessis  Monica R. Handler 《Journal of Geochemical Exploration》2011

Stratigraphy, structure and host-rock chemistry are dominant controls on the location of Au in Archaean greenstone-hosted Au deposits, but the stratigraphy in such deposits is seldom obvious due to the monotonous nature of the host rocks or pervasive alteration associated with Au mineralisation. Portable, hand-held, X-ray fluorescence (pXRF) spectrometry provides a method to rapidly collect large amounts of whole-rock geochemical data that can yield new insights into both stratigraphy and Au localisation. Here we present results of pXRF analyses of samples from a representative section through Au-mineralised amphibolite-facies metabasaltic rocks at Plutonic Gold Mine, Western Australia. These data illustrate a geochemical stratigraphy in which individual lava flows can be identified on the basis of element concentrations. The most evolved basalts are at the structural base of the succession, and the least evolved at the top of the sequence, confirming previous geochemical interpretations and textural evidence that the sequence is overturned, and demonstrating for the first time that the presented section does not involve significant structural repetition. In conjunction with Au assay data, the pXRF data reveal that Au commonly occurs along basalt flow boundaries. The elemental concentration data clearly demonstrates for the first time the stratigraphic control on Au mineralisation that is not readily apparent at the macroscopic level. The methods described in this paper are readily applied, and have the potential to enhance the understanding of otherwise unclear stratigraphy and its control on mineralisation in many different types of deposits worldwide.  相似文献