Core Jamming in Unconsolidated Formations     

Peixoto Filho  Flávio Tito  Vargas Junior  Euripedes do Amaral  Santos  Erick Slis Raggio  Ferreira  Francisco Henriques 《Geotechnical and Geological Engineering》2021,39(6):4127-4142

Geotechnical and Geological Engineering - In coring operations, core jamming is a permanent concern, taking place when the rock core sample becomes stuck within the inner core barrel, thus...  相似文献   

An interactive multi-scale integrated assessment of future regional water availability for agricultural irrigation in East Anglia and North West England     

C. Henriques  I. P. Holman  E. Audsley  K. Pearn 《Climatic change》2008,90(1-2):89-111

A multi-scale approach has linked farm level decisions with regional water availability assessments that allow for environmental water needs and the competing demands for water. This is incorporated within a user-interactive software tool, enabling the impact of a range of variables to be easily examined. Climate change leads to increased potential irrigation demand in East Anglia and North West England. Under baseline socio-economic conditions, results suggest that such increased future water demands can be met in the North West, but in the drier East Anglian region are counter to the decreasing water availability under all climate scenarios. The decreasing availability is moderated or exacerbated according to the environmental priorities of the future socio-economic scenarios. Under economically focussed regional futures, water supply availability increases at the expense of the environment, despite high water demands. Under environmentally focussed futures, demand restrictions are needed due to the further decreased water availability as a consequence of the high environmental priority. Results show that the effectiveness of water pricing for reducing irrigation demand is also scenario-dependent. Where regional food production is important, irrigation demand is relatively price-insensitive and abstraction controls will be most effective, whereas in a global market-drive future, irrigation demand is shown to be price-sensitive.  相似文献   

Kimberlitic sources of super-deep diamonds in the Juina area,Mato Grosso State,Brazil     

Felix V. Kaminsky  Sergei M. Sablukov  Elena A. Belousova  Paulo Andreazza  Mousseau Tremblay  William L. Griffin 《Lithos》2010,114(1-2):16-29

The Juina diamond field, in the 1970–80s, was producing up to 5–6 million carats per year from rich placer deposits, but no economic primary deposits had been found in the area. In 2006–2007, Diagem Inc. discovered a group of diamondiferous kimberlitic pipes within the Chapadão Plateau (Chapadão, or Pandrea cluster), at the head of a drainage system which has produced most of the alluvial diamonds mined in the Juina area. Diamonds from placer deposits and newly discovered kimberlites are identical; they have super-deep origins from the upper-mantle and transition zone. Field observations and petrographic studies have identified crater-facies kimberlitic material at seven separate localities. Kimberlitic material is represented by tuffs, tuffisites and various epiclastic sediments containing chrome spinel, picroilmenite, manganoan ilmenite, zircon and diamond. The diamond grade varies from 0.2–1.8 ct/m³. Chrome spinel has 30–61 wt.% Cr₂O₃. Picroilmenite contains 6–14 wt.% MgO and 0.2–4 wt.% Cr₂O₃. Manganoan ilmenite has less than 3 wt.% MgO and 0.38–1.41 wt.% MnO. The ¹⁷⁶Hf/¹⁷⁷Hf ratio in kimberlitic zircons is 0.028288–0.28295 with ε_Hf = 5.9–8.3, and lies on the average kimberlite trend between depleted mantle and CHUR. The previously known barren and weakly diamondiferous kimberlites in the Juina area have ages of 79–80 Ma. In contrast, zircons from the newly discovered Chapadão kimberlites have a mean ²⁰⁶Pb/²³⁸U age of 93.6 ± 0.4 Ma, corresponding to a time of magmatic activity related to the opening of the southern part of the Atlantic Ocean. The most likely mechanism of the origin of kimberlitic magma is super-deep subduction process that initiated partial melting of zones in lower mantle with subsequent ascent of proto-kimberlitic magma.  相似文献   

Ground-based measurements of the methane distribution on Titan     

Paulo F. Penteado  Caitlin A. Griffith 《Icarus》2010,206(1):345-7996

Using spectra taken with NIRSPEC (Near Infrared Spectrometer) and adaptive optics on the Keck II telescope, we resolved the latitudinal variation of the 3ν₂ band of CH₃D at 1.56 μm. As CH₃D is less abundant than CH₄ by a factor of 50±10×10^-5, these CH₃D lines do not saturate in Titan’s atmosphere, and are well characterized by laboratory measurements. Thus they do not suffer from the large uncertainties of the CH₄ lines that are weak enough to be unsaturated in Titan. Our measurements of the methane abundance are confined to the latitude range of 32°S-18°N and longitudes sampled by a 0.04″ slit centered at ∼195°W. The methane abundance below 10 km is constant to within 20% in the tropical atmosphere sampled by our observations, consistent with the low surface insolation and lack of surface methane [Griffith, C.A., McKay, C.P., Ferri, F., 2008. Astrophys. J. 687, L41-L44].  相似文献   

Geo-environmental mapping using physiographic analysis: constraints on the evaluation of land instability and groundwater pollution hazards in the Metropolitan District of Campinas,Brazil     

Paulo Cesar Fernandes-da-Silva  Ricardo Vedovello  Claudio Jose Ferreira  John Canning Cripps  Maria Jose Brollo  Amelia Joao Fernandes 《Environmental Earth Sciences》2010,61(8):1657-1675

Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper, a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow. Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of ground properties. The paper also discusses constraints on- and limitations of- the approaches taken.  相似文献   

The influence of shrimp farms organic waste management on chemical water quality   总被引：1，自引：0，他引：1  

Carlos Augusto Ramos e Silva  Pablo Bezerra Dávalos  Leonel da Silveira Lobo Sternberg  Flavo Elano Soares de Souza  Maria Helena Constantino Spyrides  Paulo Sérgio Lucio 《Estuarine, Coastal and Shelf Science》2010

We evaluated the physical–chemical properties and nutrient concentrations in two shrimp ponds under conventional management, intensive (I-P) and semi-intensive (SI-P), and one under organic management (O-P), three days after loading and before stoking. The mean’s total alkalinity concentrations were 2.26 ± 0.04 mM, 2.28 ± 0.01 mM and 2.59 ± 0.01 mM, respectively for I-P, SI-P and O-P. Bicarbonate and carbonate accounted for 62% and 37% in I-P, 64% and 36% in SI-P and 83–17% in O-P, respectively. Aragonite and calcite were oversaturated around Ω = 5. Mean total phosphate (TP) concentrations were 441.37 ± 92.06 μg/L, 449 ± 48 μg/L and 473.64 ± 84.17 μg/L, under I-P SI-P and O-P management respectively. Following this sequence, NO₃⁻ concentration was 2.98 ± 0.7 μg/L, 1.16 ± 0.16 μg/L and 0.32 ± 0.12 μg/L, under I-P, SI-P and O-P management respectively. Thus, the data suggest that different management of farm organic waste leads to different chemical water quality.  相似文献   

Nomospace and genospace: A spatial matrix     

Paulo Cesar da Costa Gomes 《GeoJournal》2004,60(4):339-344

We are concerned here with the notion of space as a primary condition for building social relations. From this stand, we have created two analytical matrixes that can help us characterize two modes: that of ‘being-there-in-space’ and that of ‘being-of-the-space’; the nomospace and the genospace. While the nomospace is characterized by ‘cold’ connotations, which are ideally defined as a result of a logical option, the genospace is mainly characterized by emotional or ‘warm’ connotations, which originate from a feeling of shared nature and common destiny. We believe that these matrixes could help us to identify the meanings of some behaviours and, therefore, make us more capable of interpreting many dynamics that occur in modern societies. The importance of geography is justified by the existing relationship between these behaviours and their proper spatial form. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Geochronological evidence for pervasive Miocene weathering,Minas Gerais,Brazil     

Isabela de O. Carmo  Paulo Vasconcelos 《地球表面变化过程与地形》2004,29(11):1303-1320

⁴⁰Ar/³⁹Ar laser incremental‐heating analyses of 22 individual grains of supergene cryptomelane from three weathering pro?les, up to 400 km apart, in the Rio Doce valley and Barbacena regions at Minas Gerais, Brazil, show that the formation of weathering pro?les in these regions is contemporaneous, suggesting a strong weathering event in the Middle to Late Miocene (10–8 Ma). The preservation of these Miocene samples at or near the present surface suggests that either erosion rates have been very low in the region since the Miocene or that a much thicker weathering mantle was present in the region originally. Assuming a constant thickness of weathering pro?les in the region throughout the Tertiary, we may calculate weathering front propagation rates of 4–8 m Myr^?1 during the past 10 Ma. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Generalized thermostatistics and wavelet analysis of solar wind and proton density variability     

Maurício Jos Alves Bolzan  Reinaldo Roberto Rosa  Fernando Manuel Ramos  Paulo Roberto Fagundes  Yogeshwar Sahai 《Journal of Atmospheric and Solar》2005,67(17-18):1843

In this paper, we analyze the probability density function (PDF) of solar wind velocity and proton density, based on generalized thermostatistics (GT) approach, comparing theoretical results with observational data. The time-series analyzed were obtained from the SOHO satellite mission where measurements were sampled every hour. We present in the investigations data for two years of different solar activity: (a) moderate activity (MA) period (1997) and (b) high activity (HA) period (2000). For the MA period, the results show good agreement between experimental data and GT model. For the HA period, the agreement between experimental and theoretical PDFs was fairly good, but some distortions were observed, probably due to intermittent characteristics of turbulent processes. As a complementary analysis, the global wavelet spectrum (GWS) was obtained, allowing the characterization of the predominant temporal variability scales for both periods and the stochastic aspects of the nonlinear solar wind variability are discussed.  相似文献   

7th Latin-American Conference on Space Geophysics, Atibaia, SP, Brazil, March 29–April 2, 2004     

Barclay Clemesha  Chairman&#x;Colage Editorial Committee  Cristina Mandrini  Paulo Batista  Inez Batista  Abraham Chian  Co-editors 《Journal of Atmospheric and Solar》2005,67(17-18)

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