Audiomagnetotelluric investigations of shallow sedimentary basins in northern Sudan

Audiomagnetotelluric (AMT) investigations were carried out to study shallow sedimentary basins in northern Sudan and southern Egypt. Unlike recordings in settled areas, the natural variations (atmospherics) in the eastern Sahara were completely unperturbed by cultural noise, usually yielding very high data quality. Typical recordings and spectra are presented. The atmospherics show distinct daily variations, with maximum amplitudes in the local afternoon/night hours. As a sort of calibration, AMT measurements together with DC-resistivity and electromagnetic soundings were conducted at several groundwater boreholes. Under favourable conditions, a vertical anisotropy may be resolved by joint inversion of DCR and AMT data. The results of a case study in the Es Safya basin (NW Sudan) are presented. The investigations were aimed at determining basement depths and groundwater levels, as well as the direction and dip of major bounding faults. 2-D modelling and inversion revealed the overall conductivity structure of this shallow graben. The AMT method proved to be a valuable tool for a comparatively swift reconnaissance study of shallow structures.     

Female circumcision and ethnic identification in Sudan with special reference to the Berti of Darfur1

This article assesses the state of female circumcision in the Sudan with the primary emphasis being placed on the Berti of Darfur. Among other things, the article examines the factors that have so far led to the perpetuation of the practice and the failure of the anti-circumcision campaign. The author suggests a renewal of the campaign through the use of a comprehensive approach which encompasses the social, aesthetic, medical, identificational and religious variables involved in the practice. This revised version was published online in July 2006 with corrections to the Cover Date.     

Islam and cultural identity among the Berti of Sudan1

Focusing on the Berti of Sudan, this article assesses the role of Islam and Arabism as important variables in the social construction of cultural identity of the studied people. In line with most relevant recent literature, the author looks at cultural identity as a social construct, a dynamic ideology of shifting borders and a historical process that is grounded on diachronic social formation. The article argues that the present Berti identity is a conscious reflection of their subordinate position vis-à-vis the kingdoms and states which have dominated Sudan over the past few centuries. This revised version was published online in July 2006 with corrections to the Cover Date.     

苏丹-南苏丹穆格莱德盆地苏夫焉凹陷构造特征及演化

通过识别地震剖面构造样式、恢复骨干剖面构造演化历史,研究了苏丹-南苏丹穆格莱德盆地苏夫焉凹陷构造特征及其构造演化。结果表明：苏夫焉凹陷整体为南陡北缓的地堑结构,构造格局呈现东西分区、南北分带,正断层相关构造样式可识别出“两类五种”,其中以基底卷入型铲式正断层、沉积盖层旋转型平面正断层为主。伴随中非剪切带以及周缘板块的构造演化,凹陷经历了早白垩世巴雷姆期-晚白垩世土伦期、晚白垩世末期-古近纪古新世、新近纪至今3期强-弱-弱断坳演化阶段,其中在第一演化阶段的早期-Abu Gabra组第四段、第五段沉积时期,沉积中心位于凹陷中南部,而之后的演化阶段,沉积中心位于紧邻南部边界断层的洼陷带,并由此推测凹陷中部将是深层系（Abu Gabra 4段）油气勘探的有利区。     

Use of remote sensing to map gully erosion along the Atbara River, Sudan

The problems and impact of gully erosion along the Atbara River (Sudan), situated in semi-arid and arid environments, were investigated. The total gross area of gullied land and the loss of arable land by gully erosion were estimated. Multi-date sets of panchromatic aerial photographs and Landsat images (TM) were selected to represent two sites in the arid (New Halfa) and semi-arid (Showak town) zones along the Atbara River. Photo interpretation was conducted using physiographic and element methods. The interpretations detected the effects of water action in different climatic zones on geology, lithology, vegetation and land use. The results showed that the traditional rainfed agriculture has accelerated gully erosion in the semi-arid rather than in the arid zone. The progressive rate of gully erosion in the semi-arid zone resulted in loss of arable land at about 13.4 km² yr-1 and 9.8 km² yr-1 in the periods 1985–1987 and 1987–1990, respectively. The study provided data on the monitoring and mapping of gully erosion along the Atbara River and its tributaries.     

Thermochronological data from Sudan in the frame of the denudational history of the Nubian Red Sea margin

Low‐temperature thermochronology provides information on the timing of rifting and denudation of passive margins, and the Red Sea with its well‐exposed, young rift margins is a suitable setting for its application. Here we present new apatite fission‐track (AFT) data from Sudan northern hinterland and Red Sea coastal areas. From the former region we obtained ages between 270 ± 2 Ma ad 253 ± 53 Ma, and from the coastal belt between 83 ± 8 Ma and 39 ± 7 Ma. These data prompted a review and comparison with low‐temperature thermochronological data from the whole Nubian Red Sea Margin, and a discussion on their implication in assessing the margin evolutionary style. AFT data are available for Egypt and Eritrea as well as apatite (U‐Th)/He (AHe) ages for two transects transversal to the margin in Eritrea. Both in Egypt and Eritrea AFT data record a cooling event at about 20–25 Ma (Early Miocene) and an earlier, more local, cooling event in Egypt at about 34 Ma (Early Oligocene). The thermal modeling of the Sudan samples provides an indication of a rapid cooling in Miocene times, but does not support nor rules out an Early Oligocene cooling phase. The re‐assessment of new and existing thermochronological data within the known geological framework of the Nubian and conjugate Arabian margins favours the hypothesis that early rifting stages were affecting the whole Gulf of Suez–Red Sea–Gulf of Aden system since the Oligocene. These precocious, more attenuated, phases were followed by major extension in Miocene times. As to the mode of margin evolution, AFT age patterns both in Egypt and Eritrea are incompatible with a downwarp model. The distribution of AHe ages across the Eritrean coastal plain suggests that there the escarpment was evolving predominantly by plateau degradation. Copyright © 2009 John Wiley & Sons, Ltd.     

苏丹北部拜尤达地区金矿地质特征及找矿远景

苏丹拜尤达地区位于苏丹北部尼罗河州,区内已圈定1处中型金矿床,7处金矿找矿靶区.根据拜尤达地区金矿成矿地质条件及哈佳吉中型金矿床的地质特征、矿石和围岩的微量元素地球化学特征,将金矿床成矿过程分为热液期、表生氧化期和风化沉积期.认为该地区金矿为受区域韧性剪切带控制的中温浅成变质热液矿床,属造山型金矿.成矿物质主要来源于前寒武系变质岩,造山作用引起构造—岩浆活动,区域变质作用造成流体的活化,并萃取围岩中的成矿物质,最终在构造有利部位富集形成金矿床.     

URBAN PLANNING： A TOOL FOR URBAN POVERTY ALLEVIATION IN SUDAN

In the past few dacades, urbanization and urban growth have been increasing rapidly in many of the developing countries. It is expected that over 50% of the world population will live in cities in 2005. The growing trend indicates that as many as one fifth of all households still remain with housing tenure problems, which they try to solve through very expensive rentals, insecurity, socially and environmentally-hazardous squatting or unhealthy overcrowding, sometimes ending up with none at all. And hence, proper planning is necessary in urban development policies to improve human settlement managements in a sustainable way. This article has tried to handle urban poverty in the Sudan to a reasonable level of detail. It dealt with selected areas with regard to promotion of sustainable human settlement. The study managed to identity some recent progress in Sudanese human settlements, that is, however, still accompanied by numerous serious instances of decline in the urban environment, especially that of the greater Khartoum.Such instances of environmental deterioration are profiled and analyzed by the study with respect to all human settlement aspects of management, land-use, infrastructure, energy and transport. The paper‘s conclusion emphasized that improving all these aspects is of high priority.     

Models for recession flows in the upper Blue Nile River

Stream‐flow recessions are commonly characterized by the exponential equation or in the alternative power form equation of a single linear reservoir. The most common measure of recession is the recession constant K, which relates to the power function form of the recession equation for a linear reservoir. However, in reality it can be seen that the groundwater dynamics of even the simplest of aquifers may behave in a non‐linear fashion. In this study three different storage–outflow algorithms; single linear, non‐linear and multiple linear reservoir were considered to model the stream‐flow recession of the upper Blue Nile. The recession parameters for the linear and non‐linear models were derived by the use of least‐squares regression procedures. Whereas, for the multiple linear reservoir model, a second‐order autoregressive AR (2) model was applied first in order to determine the parameters by the least‐squares method. The modelling of the upper Blue Nile recession flow performed shortly after the wet season, when interflow and bank storage may be contributing considerably to the river flow, showed that the non‐linear reservoir model simulates well with the observed counterparts. The variation related to preceding flow on a recession parameter of the non‐linear reservoir remains significant, which was obtained by stratification of the recession curves. Although a similar stratification did not show any systematic variation on the recession parameters for the linear and multiple linear reservoir models. Copyright © 2004 John Wiley & Sons, Ltd.     

An evaluation of Radarsat-2 individual and combined image dates for land use/cover mapping

Various land use/cover types exhibit seasonal characteristics which can be captured in remotely sensed imagery. This study examined how different seasons of Radarsat-2 data influence land use/cover classification accuracies for two study sites. Two dates of Radarsat-2 C-band quad-polarised images were obtained for Washington, DC, USA and Wad Madani, Sudan. Spectral signatures were extracted and used with a maximum likelihood decision rule for classification and thematic accuracies were then determined. Both despeckled radar and derived texture measures were examined. Thematic accuracies for the two despeckled image dates were similar with a difference of 3% for Washington and 6% for Sudan. Merging the despeckled images for both seasons increased overall accuracy by 2% for Washington and 9% for Sudan. Further combining the original radar for both seasons with derived texture measures increased overall accuracies by 9% for Washington and 16% for Sudan for final overall accuracy values of 73 and 82%.