U–Pb ages,geochemistry, C–O–Nd–Sr–Hf isotopes and petrogenesis of the Catalão II carbonatitic complex (Alto Paranaíba Igneous Province,Brazil): implications for regional-scale heterogeneities in the Brazilian carbonatite associations     

Guarino  Vincenza  Wu  Fu-Yuan  Melluso  Leone  de Barros Gomes  Celso  Tassinari  Colombo Celso Gaeta  Ruberti  Excelso  Brilli  Mauro 《International Journal of Earth Sciences》2017,106(6):1963-1989

International Journal of Earth Sciences - The Catalão II carbonatitic complex is part of the Alto Paranaíba Igneous Province (APIP), central Brazil, close to the Catalão I complex....  相似文献   

L'organisation capitaliste du territoire et le problème du logement en Italie     

Giuseppe Dematteis  Giovanna Di Meglio  Gino Lusso  Anna Segre  Augusto Buscaglia 《Geoforum》1977,8(2):89-98

The capitalistic organization of territory and the housing problem in Italy.This paper provides the first results of a research programme regarding the selective and spatially differentiated use of the Italian territory by private capital in the housing sector.According to the 1971 census, in Italy there were 63,8 million rooms for 53,2 million inhabitants. As regards the 1951 census the increase of rooms has been of 26,5 million, i.e. of 70.9%, as against an increase of 15,6% of the population. In this period the investment in dwelling-houses has represented about 30% of total fixed investments which is more than in the other E.E.C. countries.The Italian building stock (with a medium average of 1.2 rooms per inhabitant), is theoretically sufficient to satisfy the population needs. This ratio, however, drops to 1.06 if we exclude the 7.6 million rooms in non-inhabited houses (“holiday houses”, new unsold houses, abandoned homes because of emigration or because of their poor conditions).Moreover, more than one third of the Italian population lives in overcrowded conditions (less than one room per person) and poor standard houses are 40% of the total.This is not only due to the fact that public investments in the housing sector have been insignificant (6% in the last ten years), or to the unequal social distribution of revenue, but also, moreover, to the speculative character of the building activity.The economic analysis shows that between 1951 and 1971, in the expansive stages of housing production, net incomes of the building and land sector have increased more rapidly than the total earned incomes and that they have been higher than the amount of investments in the sector. So, building and land estate rent have been among the main components of the Italian capitalistic accumulation through the exporpriation of a prominent share of wages. At the same time, the ever increasing growth in housing prices both for sale and for rent has forbidden the fulfilment of the needs of the lower classes, extending in an abnormal way the production of luxury and “holiday houses” to satisfy the requirements of the higher classes. This is the cause of the above mentioned contradiction between the amount of the unused or subused building stock and the existence of a large number of sub-standard and/or overcrowded houses.This mechanism of accumulation-expropriation worked because of a specific spatial structure. Its main character consists in a strong geographical concentration of the basic activities and of the population. 53.3% of 1960–1971 housing production has concentrated in 4.7% of the Italian communes with more than 20,000 inhabitants.The analysis carried out on a stratified sample including 1,524 communes allowed us to reach the following results: 1. We find situations of greater unsatisfaction of the needs in the largest industrial metropolitan north-western areas and in the underdeveloped southern communes with strong emigrations. 2. We have had the highest offer for houses, as regards the needs, in the communes with less than 5,000 inhabitants, in the communes with less than 250,000 inhabitants, with prevalently tertiary functions, and in the districts where development is more equilibrated, from a territorial point of view (i.e.: north-eastern Italy). 3. The mechanism of accumulation-expropriation worked mainly in the industrial areas and it grows at the ever increasing growth of agglomerations and urban overcrowding, determined by strong migratory flows. 4. Building activity of tertiary communes has been led, mainly, by the higher-class expansion of consumptions. 5. The same kind of demand has given rise to the strong increase of “holiday houses” which interests large periurban, coastal and Alpine areas. 6. The housing sector becomes in this way a component of territorial disequilibriums, caused by the industrial and tertiary polarization and it is inclined to enlarge them by the artful increase of urban rent. 7. This use of territory has the aim to encourage incomes removal among different social classes and to contribute in this way, to the process of capitalistic accumulation. But, by doing this, it causes a kind of growth, in the housing sector, which is unable to satisfy lower-class needs for houses. 8. The attainment of this last purpose would, therefore, mean an efficient regional planning and the elimination of urban rent, conditions which are in opposition to the maintenance of the present economic and social structure of the Italian economy, of which speculative building and rent sectors are, nowadays, essential components.  相似文献   

Temporal variability of throughfall as a function of the canopy development stage: from seasonal to intra-event scale     

José Bandeira Brasil  Eunice Maia de Andrade  Helba Araújo de Queiroz Palácio  Julio Cesar Neves dos Santos  Pedro Henrique Augusto Medeiros 《水文科学杂志》2020,65(10):1640-1651

ABSTRACT

The interception process impacts rainfall magnitude and intensity under the canopy. In this study, the effect of plant interception on throughfall characteristics was assessed in the deciduous Caatinga vegetation, at different canopy development stages and for temporal scales ranging from seasonal to the intra-event scale. Throughfall and stemflow percentages were slightly higher at the onset of the rainy season, when leaf area density is low, with resulting lower interception losses. However, there was no statistical difference among the variables at the seasonal scale. At the intra-event scale, average and maximum throughfall intensity at different time intervals showed statistical difference between the stages of canopy development. Regardless of leaf area density and rainfall depth, vegetation is able to retain all the water up to 2 min in the beginning of each rainfall event with accumulated rainfall smaller than 0.6 mm. Furthermore, the Caatinga vegetation attenuates the rainfall intensity by 30–40%.  相似文献   

Coupled conduit and atmospheric dispersal dynamics of the AD 79 Plinian eruption of Vesuvius     

Augusto Neri  Paolo Papale  Dario Del Seppia  Roberto Santacroce 《Journal of Volcanology and Geothermal Research》2003,120(1-2):141-160

The AD 79 eruption of Vesuvius is certainly one of the most investigated explosive eruptions in the world. This makes it particularly suitable for the application of numerical models since we can be quite confident about input data, and the model predictions can be compared with field-based reconstruction of the eruption dynamics. Magma ascent along the volcanic conduit and the dispersal of pyroclasts in the atmosphere were simulated. The conduit and atmospheric domain were coupled through the flow conditions computed at the conduit exit. We simulated two different peak phases of the eruption which correspond to the emplacement of the white and gray magma types that produced Plinian fallout deposits with interlayered pyroclastic flow units during the gray phase. The input data, independently constrained and representative of each of the two eruptive phases, consist of liquid magma composition, crystal and water content, mass flow rate, and pressure–temperature–depth of the magma at the conduit entrance. A parametric study was performed on the less constrained variables such as microlite content of magma, pressure at the conduit entrance, and particle size representative of the eruptive mixture. Numerical results are substantially consistent with the reconstructed eruptive dynamics. In particular, the white eruption phase is found to lead to a fully buoyant eruption plume in all cases investigated, whereas the gray phase shows a more transitional character, i.e. the simultaneous production of a buoyant convective plume and pyroclastic surges, with a significant influence of the microlite content of magma in determining the partition of pyroclast mass between convective plumes and pyroclastic flows.  相似文献   

Stratigraphic responses to a major tectonic event in a foreland basin: the Ecuadorian Oriente Basin from Eocene to Oligocene times   总被引：2，自引：0，他引：2  

Frdric Christophoul  Patrice Baby  Celso Dvila 《Tectonophysics》2002,345(1-4)

The Eocene to Oligocene sediments of the Ecuadorian Oriente Basin record two kinds of second-order stratigraphic response to the tectonic evolution. Lower Eocene shows evidences of local scale syntectonic deposits. This tectonic activity can be related to right lateral convergent movements inverting pre-cretaceous extensional structures. Upper Eocene and Oligocene sediments are integrated as the expression of an isostatic rebound characterizing a basin scale syntectonic deposition. This response is evidenced by a reciprocal architecture of the depositional sequences identified in the sedimentary formations. These data have allowed us to propose a new geodynamic model for the Paleogene evolution of the Oriente Basin.  相似文献   

First Late Ordovician Paleomagnetic Pole for the Cuyania (Precordillera) Terrane of Western Argentina: a Microcontinent or a Laurentian Plateau     

Augusto E. Rapalini  Carlos A. Cingolani 《Gondwana Research》2004,7(4):1089-1104

Time and tectonic processes involved in docking of the Argentine Precordillera (Cuyania terrane) against SW Gondwana has been a matter of much debate. A paleomagnetic study on the Early Caradoc Pavón Formation, exposed in the San Rafael block, province of Mendoza, Argentina, is presented. After detailed thermal and alternating field demagnetizations two geologically significant magnetic components were defined. A widespread post-tectonic component (A) is present in most sites of the Pavón Formation, with dual polarities, and is coincident with the characteristic remanence isolated from a Permo-Triassic rhyolitic dome intruding the sediments. Its pole position (83.7°S, 271.0°E, dp = 6.8°, dm = 9.0° N = 11 sites) falls on the Late Permian-Early Triassic South American reference poles suggesting that this component was acquired during the Choiyoi magmatic phase. A second component (B) also shows dual polarities and a positive fold test suggesting a primary origin. Unblocking temperatures and rock magnetic experiments indicate that B is carried either by hematite or magnetite at different sites. Anisotropy of magnetic susceptibility results suggest a depositional fabric and no remanence distortion due to deformation or compaction. A paleomagnetic pole computed from this remanence (PV) falls on 3.6°N, 346.4°E (dp = 2.9°, dm = 4.6° n = 22 samples). It indicates a paleolatitude around 26°S for deposition of Pavón sediments and constrains the paleogeographic evolution of Cuyania during the Ordovician, which was still at subtropical latitudes by the Early Caradoc. PV is consistent with the Laurentian Late Ordovician reference pole if Cuyania remains attached to SE Laurentia for the Early Caradoc, while it shows a significant cw rotation with no paleolatitude anomaly respect to the Gondwana reference pole when kept in its present position in SW South America. These comparisons are interpreted in three possible alternatives for the paleogeographic and tectonic setting of Cuyania in the Late Ordovician.  相似文献   

U/Th age constraints on the absence of ice in the central Inn Valley (eastern Alps, Austria) during Marine Isotope Stages 5c to 5a     

Christoph Spötl  Augusto Mangini 《Quaternary Research》2006,66(1):167-175

Calcitic flowstones are present in fractures of a Pleistocene breccia near Innsbruck, Austria, and record periods of carbonate precipitation in the unsaturated zone between 101,500 ± 1500 and 70,300 ± 1800 yr, constrained by U-series disequilibrium dates. The occurrence of these speleothems, their low carbon isotopic composition, and the lack of infiltrated siliciclastic material demonstrate that the central Inn valley - which harbored one of the most extensive valley glaciers during the last glacial maximum - was ice-free during Marine Isotope Stages 5c to 5a. Climatically warm periods are separated by distinct drops in the oxygen isotopic composition of the speleothem calcite, attributed to strong and possibly seasonally biased atmospheric cooling. During these intervening stadials, which mirror those identified in the Greenland ice cores and marine sea-surface temperature records, calcite deposition apparently came to a halt, but the Inn Valley remained ice-free. The youngest calcite layer formed between ∼74,000 and ∼70,000 yr and places a maximum age limit on the likely expansion of alpine glaciers during the Marine Isotope Stage 5/4 transition, consistent with other speleothem records.  相似文献   

Arsenic in the groundwater of Ouro Preto (Brazil): its temporal behavior as influenced by the hydric regime and hydrogeology     

José Augusto Costa Gonçalves  Jorge Carvalho de Lena  José Fernando Paiva  Hermínio Arias Nalini Jr  Janice Cardoso Pereira 《Environmental Geology》2007,53(4):785-793

In the city of Ouro Preto (MG), water catchment for public supply originates from superficial drainage, springs, old abandoned mines and some driven wells. In the rocks of the region, As is originally found in gold-enriched sulphide-bearing mineral deposits. The weathering process introduces As into the hydrological system by dissolution of this element into the leachate. Measurement of the As content in the groundwater of some catchments was carried out during 1 year and these measurements demonstrated high As content—up to 224 μg L⁻¹ of As(V)—during the rainy season (the maximum concentration limit according to World Health Organization is 10 μg L⁻¹). Lower values were observed during the dry season and in some sampling stations, As was not even detected. The As concentration variability during 1 year shows a strict and direct relationship to seasonal and hydrological conditions. For city authorities, responsible for public water supply, it is necessary to perform a complete inventory of the water sources used and constantly monitor the As content in the water.  相似文献   

Characterization and evaluation of a tropical peat for the removal of Cr(VI) from solution     

Marilia Mayumi Augusto dos Santos  Mirian Chieko Shinzato  Juliana Gardenalli de Freitas 《Environmental Earth Sciences》2018,77(13):515

Tropical peat soils present higher ash content than those generated at temperate climate areas. Therefore, this study evaluated the characteristics of a Brazilian organic soil (OS), commercialized as peat, as well as its capacity in removing Cr(VI) from contaminated waters. The OS is composed of 35.5 wt% of organic matter and 56 wt% of inorganic fraction (ash), which is formed by minerals and phytoliths rich in silica (29.2 wt%) and alumina (23.6 wt%). The Cr(VI) removal tests were carried out in batch and column systems using OS and solutions of Cr(VI) prepared with distilled water and groundwater. Batch tests revealed that the organic substances in the OS caused the reduction of Cr(VI) to Cr(III), with an efficiency depending on solution pH. At pH 5.0 the Cr(VI) removal was 0.45 mg g^?1 in 24 h; whereas at pH 2.0, this removal increased to 1.10 mg g^?1. Since this redox reaction is very slow, the removal of Cr(VI) at pH 5.0 increased to around 2 mg g^?1 after 5 days. The removal of Cr(VI) was more effective in the column tests than in the batch test due to the greater solid/solution ratio, and their half-lives were 4.4 and 26.2 h, respectively. Chemical analysis indicated that Cr(VI) was reduced by the humic substances of OS, followed by the precipitation and/or adsorption of Cr(III) into the organic and inorganic components, as anatase. The presence of Cr(III) increased the stability of anatase structure, avoiding its transformation into rutile, even after being heated at 800 °C/2 h.  相似文献   

Wavelet-based variability on streamflow at 40-year timescale in the Black Sea region of Turkey     

Celso Augusto Guimarães Santos  Ozgur Kisi  Richarde Marques da Silva  Mohammad Zounemat-Kermani 《Arabian Journal of Geosciences》2018,11(8):169

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