Upper Proterozoic and Phanerozoic Pole Positions and Potassiumargon (K-Ar) Ages From the East Sahara Craton     

S. Saradeth  H. C. Soffel  P. Horn  D. Müller-Sohnius  A. Schult 《Geophysical Journal International》1989,97(2):209-221

  相似文献   

Evolution of the Neoproterozoic Delgo suture zone and crustal growth in Northern Sudan: geochemical and radiogenic isotope constraints     

U. Harms  D. P. F. Darbyshire  T. Denkler  M. Hengst  H. Schandelmeier 《International Journal of Earth Sciences》1994,83(3):591-603

In the Delgo basement area of northern Sudan, low to medium grade metamorphosed volcanic, sedimentary and plutonic rocks are surrounded by high grade gneisses. A NNE-SSW trending suture zone can be defined by the lithological, chemical and structural characteristics of several distinct units. The early Proterozoic gneiss terrain is overlain by metasedimentary units, the metamorphism of which has been dated by the Sm-Nd whole rock-mineral technique (702 ± 27 Ma in the west, 592 ± 16 Ma in the east). In the central part, the Abu Sari volcanic rocks show geochemical signatures of formation at an arc, with a protracted tholeiitic, calc-alkaline and shoshonitic evolution. The overlying El Hamri ophiolite contains chemical features of a back-arc tectonic environments. The ophiolite was dated by the Sm-Nd whole rock method on metagabbros at 752 ± 48 Ma. The further extension of this oceanic basin into the Jebel Rahib in the south-west was dated at 707 ± 54 Ma (Sm-Nd whole rock and minerals).Widespread suite of syn-tectonic granitoid intrusives displays subduction-related characteristics. They where emplaced between 650 to 760 Ma (Pb-zircon evaporation method). Their Nd and Sr isotopic compositions indicate a changing pattern of island arc to active continental margin character along an east-west transect and suggest a west to north-west dipping subduction zone. All units were juxtaposed at the minimum age of 600 Ma and rearranged during an extensional event, which was dated by the Rb-Sr thin slab technique (546 ± 19 Ma) on a migmatite. The Delgo suture provides evidence of a complex terrane pattern in north-east Africa and crustal growth during the Pan-African event by the addition of oceanic material to pre-existing continental crust.  相似文献   

Thermal maturity history and petroleum generation modelling for the Lower Cretaceous Abu Gabra Formation in the Fula Sub-basin,Muglad Basin,Sudan     

《Marine and Petroleum Geology》2016

Two petroleum source rock intervals of the Lower Cretaceous Abu Gabra Formation at six locations within the Fula Sub-basin, Muglad Basin, Sudan, were selected for comprehensive modelling of burial history, petroleum maturation and expulsion of the generated hydrocarbons throughout the Fula Sub-basin. Locations (of wells) selected include three in the deepest parts of the area (Keyi oilfield); and three at relatively shallow locations (Moga oilfield). The chosen wells were drilled to depths that penetrated a significant part of the geological section of interest, where samples were available for geochemical and source rock analysis. Vitrinite reflectances (Ro %) were measured to aid in calibrating the developed maturation models.The Abu Gabra Formation of the Muglad Basin is stratigraphically subdivided into three units (Abu Gabra-lower, Abu Gabra-middle and Abu Gabra-upper, from the oldest to youngest). The lower and upper Abu Gabra are believed to be the major source rocks in the province and generally contain more than 2.0 wt% TOC; thus indicating a very good to excellent hydrocarbon generative potential. They mainly contain Type I kerogen. Vitrinite reflectance values range from 0.59 to 0.76% Ro, indicating the oil window has just been reached. In general, the thermal maturity of the Abu Gabra source rocks is highest in the Abu Gabra-lower (deep western part) of the Keyi area and decreases to the east toward the Moga oilfied at the Fula Sub-basin.Maturity and hydrocarbon generation modelling indicates that, in the Abu Gabra-Lower, early oil generation began from the Middle- Late Cretaceous to late Paleocene time (82.0–58Ma). Main oil generation started about 58 Ma ago and continues until the present day. In the Abu Gabra-upper, oil generation began from the end of the Cretaceous to early Eocene time (66.0–52Ma). Only in one location (Keyi-N1 well) did the Abu Gabra-upper reach the main oil stage. Oil expulsion has occurred only from the Abu Gabra-lower unit at Keyi-N1 during the early Miocene (>50% transformation ratio TR) continuing to present-day (20.0–0.0 Ma). Neither unit has generated gas. Oil generation and expulsion from the Abu Gabra source rocks occurred after the deposition of seal rocks of the Aradeiba Formation.  相似文献   

Groundwater discharge mechanism in semi‐arid regions and the role of evapotranspiration     

Osman A. E. Abdalla 《水文研究》2008,22(16):2993-3009

The present study examined groundwater recharge/discharge mechanisms in the regional Central Sudan Rift Basins (CSRB). Aquifers in CSRB constitute poorly sorted silisiclastics of sand, clay and gravels deposited in closed hydrologic systems of the Cretaceous–Pleistocene fluviolacustrine environments. CSRB are bounded to the north by the highlands of the Central African Shear Zone (CAZS) that represents the surface and groundwater divides. Sporadic recharge in the peripheries of the basins along the CASZ occurs subsequent to decadal and centennial storm events. Inflow from the Nile into the aquifers represents an additional source of recharge. Thus, groundwater resources cannot be labelled fossil nor can they be readily recharged. Closed hydrologic troughs located adjacent to the influent Nile system mark areas of main groundwater discharge characterized by lower hydraulic heads. This study has examined mechanisms that derive the discharge of the groundwater in these closed basins and concluded that only evapotranspirative discharge can provide a plausible explanation. Groundwater abstraction is mainly through deep‐rooted trees and effective evaporation. The increase of TDS along the flow indicates local recharge at the peripheries of basins and shows the influence of evaporation and rock/water interaction. The decline in groundwater level along a flow path was calculated using Darcy's law to estimate average recharge and evapotranspirative discharge, which are equal under natural equilibrium and make the only fluxes in CSRB. Steady‐state 2D flow modelling has demonstrated that an average recharge of 4–8 mm yr^?1 and evapotranspirative discharge of 1–22 mm yr^?1 will maintain natural equilibrium in CSRB. Sporadic storms provide recharge in the highlands to preserve the current hydraulic gradient and maintain aquifer dynamics. Simulated recharge from the Nile totals about 17·5 mm yr^?1 and is therefore a significant contributor to the water balance. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

高精度磁法在苏丹红海州佛地宛铁矿找矿中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

杜汉卿  刘占途  张文华  霍印峰 《地质找矿论丛》2011,26(3):322-327

苏丹红海州的佛地宛铁矿产于元古代中性火山岩-次火山岩的断裂带中,属于裂隙充填型铁矿床.文章通过2.5维人机交互反演和磁化率三维反演模型等方法联合解释铁矿区铁矿体地表及其深部矿体特征,通过反演结果显示出铁矿体的赋存状态、规模大小和延展深度,使高精度要磁测工作获得较好的成果.  相似文献   

苏丹黑B染色处理细胞技术在快速检测微藻油脂含量中的应用   总被引：1，自引：0，他引：1  

林汝榕  邢炳鹏  蔡文旋  柯秀蓉  林锡煌 《台湾海峡》2011,30(2):292-298

探讨了采用苏丹黑B染料染色处理微藻细胞技术估测微藻油脂含量的可行性.结果表明,微藻细胞经苏丹黑B染色处理后在645 nm光波长处有最大吸收峰值A645,微藻油脂含量与经苏丹黑B染色处理后微藻细胞的吸光值A645呈明显的相关性.建立了考察的7种微藻油脂含量与吸光值A645的线性回归方程,线性关系显著（p〈0.01）.基于藻湿重,微藻油脂含量的线性范围为1.79~39.63 mg/g,估算的相对偏差〈10%.因而,采用苏丹黑B染色处理微藻细胞技术适宜用来检测微藻的油脂含量.  相似文献   

苏丹东北部金矿成矿特征及成矿远景浅析   总被引：5，自引：0，他引：5  

胡建勇 《地质与勘探》2011,47(3):505-511

文章在对苏丹东北部金矿区域构造背景、含金建造及金地球化学特征研究成果的基础上,分析了哈塞、洁比特、瑞达和哈马迪等4个研究程度较高的典型金矿床的矿体赋存规律、矿床类型和金矿石的结构构造等特征,认为该地区至少存在石英脉型、火山成因块状硫化物和韧性剪切带等3种以上金矿床类型.金矿床的形成与岩石建造、构造作用关系密切,总结了苏...  相似文献   

苏丹哈马迪金矿南矿段地质、矿化特征及采矿意义     

胡金才  智铎强  胡建勇 《前寒武纪研究进展》2013,(4):295-298

哈马迪金矿是天津华北地质勘查局近年在苏丹北部发现的中大型绿岩带型金矿。由于特殊的大地构造环境和控矿条件,哈马迪金矿南矿段表现出特异性的金矿化特征。本文通过对南矿段区域构造环境及矿区地质特征的论述,研究了该区金矿化的成因及矿化特征,总结了南矿段在无法准确勘查的情况下的采矿、综合利用方法,评述了该类金矿的经济意义。  相似文献   

Water balance of the Sudanese savannah woodland region     

Mike Starr  Syed Ashraful Alam 《水文科学杂志》2013,58(4):706-722

Abstract

The annual water balance for 39 grid cells covering the savannah woodland region of Sudan (10–16°N; 21–36°E) was determined and regional maps produced. Long-term (1961–1990) mean monthly climate data, National Forest Inventory data and Harmonized World Soil Database data for arenosols and vertisols, the two dominant soil types in the region, were used. Model validation was performed using daily data from a site in one of the grid cells and inter-annual (1961–1990) variation examined for another grid cell. Rainfall varied from 147 to 732 mm and only exceeded evapotranspiration for 18 of the grid cells, resulting in a small increase in soil moisture and runoff. Evapotranspiration accounted for, on average, 96% of rainfall and there was little difference between soil types. Drainage only occurred from AR soils and for four of the grid cells. Runoff varied from 0 to 89 mm for arenosols and from 0 to 109 mm for vertisols. The study provided useful insights into the spatial variability in water balance components across the region.