The Palaeocene–Middle Eocene deposits of Sardinia (Italy) and their palaeoclimatic significance     

Marco Murru  Concetta Ferrara  Stefania Da Pelo  Angelo Ibba 《Comptes Rendus Geoscience》2003,335(2):227-238

The Palaeocene of southern Sardinia includes a continental ferruginous sedimentation, with a high content of Al and Fe, indicative of a subhumid tropical climate. The subsequent microcodium carbonated detrital microcodium levels, containing an abundant quartzose fraction, rather suggest semiarid conditions. In SW Sardinia, the marine deposits, referred to Late Thanetian–Lower Ypresian (=Ilerdian) times, are limestones including larger foraminifers and contain significant amounts of quartz. A lower content of detrital kaolinite points a sediment source from the surrounding areas with a semiarid climate. The occurrence, at the top of this unit, of small trochospiral rotaliids and larger amount of detrital kaolinite suggests a transition to a rainy tropical climate in the adjacent areas. These limestones pass gradually to carbonate sediments characterized by large amounts of detrital kaolinite and intercalated coal layers, with pollen of tropical palms, attributed to the Late Ypresian (=Cuisian)–Early Lutetian and referred to a humid-subhumid tropical climate.  相似文献   

Jadeite with the Ca-Eskola molecule from an ultra-high pressure metagranodiorite, Dora-Maira Massif, Western Alps     

Marco Bruno  Roberto Compagnoni  Takao Hirajima  Marco Rubbo 《Contributions to Mineralogy and Petrology》2002,142(5):515-519

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Paleo-environmental and volcano-tectonic evolution of the southeastern flank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily     

Rosa Anna Corsaro  Marco Neri  Massimo Pompilio   《Journal of Volcanology and Geothermal Research》2002,113(1-2)

The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcano-tectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.  相似文献   

Signs of power: Fascist urban iconographies in Ethiopia (1930s–1940s)     

Marco Antonsich 《GeoJournal》2001,52(4):325-338

The aim of the present paper is to compare two different patterns of urban iconographies in Ethiopia during 1930s: the one of the Amhara – the traditionally Ethiopian dominant ethnicgroup – and the one of the Italian fascism. The paper gives an historical account of the structure of the Amhara settlements, focusing on the ways the power of their politico-military chiefs, being they the Negus or the Ras, shaped the spatial order of these settlements. When the Italians conquered military Ethiopia in 1936, they started re-shaping this spatial order, erasing the signs of the previous power and imposing their new iconographic apparatus. This was mainly done through urban planning which was devised to `write' the Fascist concepts of progress, order, hierarchy, and racial segregation on the territory. Owing to the short duration of the occupation, the poor material conditions of the colony and the lack of financial resources, such town-planning projects turned out to be just a political rhetoric exercise.  相似文献   

Further studies of the temperature dependence of the rate coefficients for the reactions of OH with a series of ethers under simulated atmospheric conditions     

Marco Semadeni  David W. Stocker  J. Alistair Kerr 《Journal of Atmospheric Chemistry》1993,16(1):79-93

The following temperature-dependent rate coefficients (k/cm³ molecule^–1 s^–1) of the reactions of hydroxyl radicals with aliphatic ethers have been determined over the temperature range 247–373 K by a competitive flow technique: diethyl ether,k _OH=5.2×10^–12 exp[(262±150)/T]; methyln-butyl ether,k _OH=5.4×10^–12 exp[(309±150)/T]; ethyln-butyl ether,k _OH=7.3×10^–12 exp[(335±150)/T]; di-n-butyl ether,k _OH=5.5×10^–12 exp[(502±150)/T] and di-n-pentyl ether,k _OH=8.5×10^–12 exp[(417±150)/T]. The data have been measured relative to the rate coefficientk(OH + 2,3-dimethylbutane)=6.2×10^–12 cm³ molecule^–1 s^–1 independent of temperature.Previous discrepancies in the room-temperature rate coefficients for the OH reactions with ethyln-butyl ether and di-n-butyl ether, obtained in the flow and static experiments of Bennett and Kerr (J. Atmos. Chem. 8, 87–94, 1989;10, 29–38, 1990) compared with those of Wallingtonet al. (Int. J. Chem. Kinet. 20, 541–547, 1988;21, 993–1001, 1989) and of Nelsonet al. (Int. J. Chem. Kinet. 22, 1111–1126, 1990) have been resolved. The results are considered in relation to the available literature data and evaluated rate expressions are deduced where possible. The data are also discussed in terms of structure-activity relationships.  相似文献   

Implementation of effective seismic input for soil-structure interaction systems     

Marco G. Cremonini  Paul Christiano  Jacobo Bielak 《地震工程与结构动力学》1988,16(4):615-625

A previously introduced method for transmitting effective seismic excitation to a discretized soil-structure system implemented. The method permits free-field excitation of a linear soil system to be specified within the regie of computation, arbitrarily close to a zone that includes the (possibly non-linear) structure and local subgrade and bae, thus eliminating the need to transmit the seismic excitation through artificial boundaries. This approach is demonse through a numerical example comprising a linear, two-dimensional system. Some comments also are made on the rere efficiencies of various local absorbing boundaries.  相似文献   

Benthic Fluxes of Dissolved Inorganic Nitrogen in a Coastal Lagoon of the Northern Adriatic Sea: an Interpretation of Spatial Variability Based on Sediment Features and Infauna Activity   总被引：1，自引：0，他引：1  

Daniele Nizzoli  Giuseppe Castaldelli  Marco Bartoli  David Thomas Welsh  Patricia Arriaga Gomez  Anna Elisa Fano  Pierluigi Viaroli 《Marine Ecology》2002,23(S1):297-306

Abstract. Dark respiration rates, dissolved inorganic nitrogen (DIN) fluxes and nitrification rates were measured at two sites in the microtidal Sacca di Goro lagoon in September 2000. DIN fluxes correlated with the biomass of the dominant macrofauna species (the amphipod Corophium spp. at station Giralda and the polychaete Neanthes spp. at station Faro). Respiration (> 6 mmol O₂ m⁻²h⁻¹) and ammonium fluxes (> 80μmol N m⁻²h⁻¹) were higher at station Giralda despite the lower organic matter content (4.5 %) and lower macrofauna biomass (4 g AFDW m⁻²). At both sites ammonium fluxes were significantly correlated with the biomass of the benthic infauna, but Corophium stimulated ammonium NH₄⁺ fluxes 3-fold compared to Neanthes. The amphipod also enhanced nitrification rates (> 300 μmol N m⁻²h⁻¹) due to the high density of its burrows, the higher NH₄⁺ regeneration rates and the enhanced oxygen supply to the bacteria.  相似文献   

Transtensional shear zones controlling volcanic eruptions: the Middle Pleistocene Mt Amiata volcano (inner Northern Apennines,Italy)     

Andrea Brogi  Domenico Liotta  Marco Meccheri  Lorenzo Fabbrini 《地学学报》2010,22(2):137-146

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Geochemistry of trace elements in surface waters of the Arno River Basin,northern Tuscany,Italy     

Gianni Cortecci  Tiziano Boschetti  Enrico Dinelli  Rosa Cidu  Francesca Podda  Marco Doveri 《Applied Geochemistry》2009

Trace element geochemistry of the Arno River and its main tributaries was investigated on the basis of two sampling campaigns carried out in November 1996 and June 1997. By analyzing filtered and unfiltered water samples, Fe and Al are found in solution mainly as colloidal particles of size lower than 0.45 μm. In June (lower flow rate), Fe and Al are enriched in the filtered waters from the main river, and this feature was interpreted in terms of higher water temperature promoting the formation of smaller particles, thus reducing their aggregation properties. Iron and Al show perfectly synchronous downstream profiles along the Arno River, correlate quite well each to other, and display abrupt concentration increases near to Florence, where the lithology of the catchment changes from siliciclastic dominated to clay-sand (lacustrine-marine)-dominated. The same behaviour is shown by most of the other trace elements in the river, thus supporting a general lithological control. Trace elements in the final part of the Arno River are influenced by flocculation processes in addition to mixing. Adsorption phenomena on oxy-hydroxides are denoted by good elemental correlations with Fe (and Al). Sporadic anomalous concentration values, possibly related to anthropogenic contributions, may prevent such correlations. Referring to the quality of waters for potable use and fish life, toxic elements are below the acceptable limits of current European regulations, with few exceptions for Hg exceeding guideline values. Multivariate analysis groups trace elements according to geochemical affinities and natural or anthropogenic sources, thus distinguishing contaminated from uncontaminated samples. The results achieved in this work will help regional and national Authorities for compliance with the EU water policy, especially in assessing the water quality at the river basin scale and its vulnerability to human activities.  相似文献   

Estimating location and size of historical earthquake by combining archaeology and geology in Umm-El-Qanatir,Dead Sea Transform     

Neta Wechsler  Oded Katz  Yehoshua Dray  Ilana Gonen  Shmuel Marco 《Natural Hazards》2009,50(1):27-43

We study the Byzantine-to-Ummayad (6th–8th century) archaeological site of Umm-El-Qanatir, located 10 km east of the Dead Sea Transform (DST) in northern Israel. The site was damaged by an earthquake-induced landslide, and in this work we use slope stability analysis to constrain the historical seismic acceleration that occurred along the northern segment of the DST. Umm-El-Qanatir archaeological site is located on a slope of a canyon and contains evidence for earthquake-related damage, including fallen columns and walls, horizontal shift of heavy masonry blocks, and complete burial of ceramic pots and farming tools beneath fallen ceilings. A water pool that collected spring water is displaced nearly one meter by the landslide. The artifacts from the village and the spring area indicate that people inhabited the site until the middle of the 8th century. We argue that the destruction, which forced the abandonment of Umm-El-Qanatir together with nearby settlements, was associated with the earthquake of January 18, 749 CE. In order to evaluate the ground acceleration related to the above earthquake, we back-analyze the stability of a failed slope, which cut and displaced the water-pool, using slope stability software (Slope/W). The results show that the slope is statically stable and that high values of horizontal seismic acceleration (>0.3 g) are required to induce slope failure. Subsequently, we use the Newmark displacement method to calculate the earthquake magnitude needed to cause the slope failure as a function of distance from the site. The results (attributed to the 749 CE earthquake) show that a M_W > 7.0 earthquake up to 25 km from the site could have induced the studied landslide.  相似文献