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1.
The Yaoundé belt (Cameroon) and the Sergipano belt (NE Brazil) belonged to a major and continuous Neoproterozoic orogen at the northern margin of the ancient Congo-São Francisco craton. The Yaoundé belt comprises schists, quartzites, gneisses and migmatitic gneisses grouped into three domains; the low-grade Mbalmayo Group in south and the medium- to high-grade Yaoundé and Bafia Group in north. The Sergipano belt is divided into six domains, the three southernmost of which are mostly made up of clastic and chemical metasedimentary rocks whereas the others are more diverse with a migmatite–gneiss complex, and two metavolcanicplutonic complexes. In general, the two belts show structural vergence and decrease of metamorphic grade towards the craton; three main deformation phases are recognized in the Sergipano belt in contrast with two described in the Yaoundé belt. The minimum age of Pan-African-Brasiliano collision in the Sergipano belt is constrained at 628 ± 12 Ma on syn-collision granites, whereas in the Yaoundé belt collision took place between 620 and 610 Ma, i.e. the age of granulite facies metamorphism. Sm–Nd isotope geochemistry and U–Pb age dating indicate that most clastic metasedimentary rocks in both belts were derived from sources to the north and, to a lesser degree, from the cratons to the south.  相似文献   
2.
The case study of Kanpur demonstrates the use of air photo approach to collect physical data, mainly landuse in central area. The study reveals that very less percentage of vacant land exists in central area for future development. Though this area consist CBD, even then commercial landuse accounts to be only 10% of total area. Selective landuse inventory analysis was carried out for the landuse categories, commercial, industrial and vacant. Reliability of aerial photo-interpretation of over all landuse map found to be 91–95% and each sub-class of landuse reliability for omission and commission error found to be within limits for planning and design purpose.  相似文献   
3.
We study in some detail one-dimensional NLTE effects in solar Fei lines. The lines selected are frequently used in solar polarimetry, and also in studies of line asymmetries and for abundance determinations. Our model atom for Fei–Feii–Feiii is realistic: it takes account of multiplet structure and it includes over 200 bound–bound and bound–free transitions in detail. We use very efficient iterative methods for the self-consistent solution of the kinetic and radiative transfer equations (Auer, Fabiani Bendicho, and Trujillo Bueno, 1994). We have applied these fast methods of solution because they are suitable for the investigation of 2D and 3D NLTE transfer effects with multilevel atoms, which constitutes the next step of our ongoing research project on the iron line formation problem.  相似文献   
4.
A scheme that couples a detailed building energy model, EnergyPlus, and an urban canopy model, the Town Energy Balance (TEB), is presented. Both models are well accepted and evaluated within their individual scientific communities. The coupled scheme proposes a more realistic representation of buildings and heating, ventilation and air-conditioning (HVAC) systems, which allows a broader analysis of the two-way interactions between the energy performance of buildings and the urban climate around the buildings. The scheme can be used to evaluate the building energy models that are being developed within the urban climate community. In this study, the coupled scheme is evaluated using measurements conducted over the dense urban centre of Toulouse, France. The comparison includes electricity and natural gas energy consumption of buildings, building façade temperatures, and urban canyon air temperatures. The coupled scheme is then used to analyze the effect of different building and HVAC system configurations on building energy consumption, waste heat released from HVAC systems, and outdoor air temperatures for the case study of Toulouse. Three different energy efficiency strategies are analyzed: shading devices, economizers, and heat recovery.  相似文献   
5.
Suspended solids found in porewaters obtained in waterlogged soil sequences that included representative laterite–podzol transitions, associated brooks and major rivers of the Rio Negro watershed (Brazil) were studied using electron paramagnetic resonance (EPR) and Fourier-transform infrared spectroscopies. The main goal was to ascertain sources and track the evolution of suspended matter using a ubiquitous chemical species, FeIII complexed to organic matter (FeOM). Three size fractions were separated by tangential-flow (ultra)filtration: particulate (> 0.2 μm), dense (P) and light (Ps), and colloidal (5 kD < Col. < 0.2 μm) fractions. Quantitative results were acquired for Col. and Ps fractions which are predominantly organic in nature.FeOM concentration (in ‰ dry weight) was determined to be relatively low in suspended solids found in black waters from podzol porewaters and brooks whereas in the main rivers it was several times higher. FeOM concentrations were also correlated with Fe(II)/Fe(III) ratios in solution; these ratios were high in podzol porewaters and low in the rivers. Considering that organic complexation of Fe(II) is minor when compared to that of Fe(III), two interpretations were proposed to account for the above observation. First, [FeOM] was assumed to be distributed along a mixing line, with the clear waters from laterites and the black waters from podzols being its end-members. Consequently, [FeOM] can be used to trace the source of suspended material. Second, dissolved Fe(II) from podzol areas was considered to be progressively oxidized as pore waters move towards the mainstream. According to this mechanism, iron is complexed by organic matter or precipitated as oxides, thus producing an evolution of colloidal matter. As a result of these mechanisms' action, both the high production of Fe(II) and organic matter at the waterlogged podzol–laterite transition areas are major factors affecting iron export in the Rio Negro watershed.  相似文献   
6.
西准噶尔包古图地区地层火山岩锆石LA-ICP-MS U-Pb年代学研究   总被引:13,自引:11,他引:13  
包古图地区位于西准噶尔东南部,区内出露地层主要为石炭系太勒古拉组、包古图组和希贝库拉斯组,为一套巨厚的半深海相-大陆坡相火山-火山碎屑沉积建造。这套地层的时代归属和地层层序长期以来一直存在争议。本文报导了包古图地区实测地层剖面,并从太勒古拉组玄武岩和包古图组及希贝库拉斯组凝灰岩中分别选出锆石,进行了LA-ICP-MS U-Pb年代学研究,获得206Pb/238U加权平均年龄分别为357.5±5.4Ma、332.1±3.0Ma和336.3±2.5Ma。由此确定这套地层属于早石炭世的杜内阶到维宪阶,由下到上依次为太勒古拉组、包古图组和希贝库拉斯组。  相似文献   
7.
8.
The mackerel scad Decapterus macarellus is of great social and economic importance to Cabo Verde citizens; however, in recent years catches have shown an unexplained decline. The harvest is regulated by way of a minimum legal size and a seasonal closure, with both measures based on the results of reproductive studies that did not consider the microscopic characteristics of the gonads. This study aimed to analyse the gonads microscopically in order to classify the sexual development stage of individuals and to estimate the size at first maturity and the reproductive season. This information was then used to analyse the match between the reproductive parameters and the management measures. The samples comprised 284 females (20–36 cm fork length [FL]) and 85 males (21–35 cm FL). The annual variation in gonadosomatic index and the monthly frequencies of mature phases suggest that the reproductive season occurs from March to October, with two spawning peaks, one in March and another from July to October. The current seasonal closure (from July to September) covers the main reproductive period. However, the species has a long spawning period and the timing of peaks can vary between years; hence, a reassessment of this management measure is recommended. The sizes at first maturity were estimated at 24.1 cm FL for females, and 26.6 cm FL for males. These values are higher than the minimum legal size (20 cm FL) currently established for management of the species at Cabo Verde; thus, we strongly recommend an increase in the minimum legal size in an attempt to reduce catches of immature individuals.  相似文献   
9.
谢克家  曾令森  刘静  高利娥 《岩石学报》2010,26(4):1016-1026
打拉二云母花岗岩岩体位于雅拉香波穹隆的东南,侵入到中生代以前的变质岩系(眼球状花岗质片麻岩和石榴黑云母片麻岩)和特提斯沉积岩(页岩和砂岩)中,主要由石英、斜长石、钾长石、黑云母和白云母组成,形成于~44.3Ma。打拉二云母花岗岩地球化学特征表明:打拉花岗岩具有高Al_2O_3(16.0%~17.0%)、Na_2O/K_2O(1.2)以及A/CNK比值(1.05),表明打拉花岗岩为富钠过铝质花岗岩;轻稀土(LREE)富集,重稀土(HREE)相对亏损,HREE中的Ho到Lu元素有变平的特征((Ho/Lu)_N=1.11~1.46);具有微弱或无Eu异常,Eu/Eu~*=0.87~0.95;较高的初始Sr同位素比值(~(87)Sr/~(86)Sr(i)=0.71754~0.71785)和较低的初始Nd比值(ε_(Nd)(i)=-9.15~-12.4)。打拉花岗岩具有高Sr含量(为355×10~(-6)~416×10~(-6))和Sr/Y的比值(59.1~71.5)、高La/Yb比值、低Y及HREE亏损的特征,与埃达克质花岗岩类似。上述特征表明打拉花岗岩是在较高压力条件下,以角闪岩为主的深部岩石部分熔融的结果。  相似文献   
10.
To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg?1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg?1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination.  相似文献   
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