埃及Faiyum盆地沉积物中粒度和磁化率对风沙活动的指示意义   总被引：1，自引：1，他引：0  

韩华玲  陈静  孙千里  陈中原  AlaaSalem 《湖泊科学》2011,23(2):303-310

埃及Faiyum盆地是尼罗河下游的泛滥平原,沉积物主要来自尼罗河和撒哈拉沙漠.本文通过对钻孔FYAM(孔深4.6m)沉积物的粒度、磁化率的分析,并结合石英形态、石膏和碳酸盐含量分析,旨在寻找Faiyum盆地沉积物中代表风沙活动的粒度、磁化率特征.研究结果显示,钻孔沉积物中共发现7种粒度频率曲线类型,主要为细粒组(6-2...  相似文献   

Linking diagenesis to sequence stratigraphy in fluvial and shallow marine sandstones: Evidence from the Cambrian-Ordovician lower sandstone unit in southwestern Sinai, Egypt     

Masoumeh Kordi  Brian TurnerAlaa M.K. Salem 《Marine and Petroleum Geology》2011,28(8):1554-1571

By integrating diagenesis and sequence stratigraphy, the distribution of diagenetic alterations and their impact on reservoir quality was investigated within a sequence stratigraphic framework using the fluvial and shallow marine sandstones in the Cambrian-Ordovician succession of southwest Sinai. The perographic and geochemical analysis of the studied sandstone revealed that the eogenetic alterations display fairly systematic spatial and temporal distribution patterns within the lowstand system tract and transgressive system tract, as well as along the sequence stratigraphic surfaces (i.e., sequence boundaries, transgressive surfaces and parasequence boundaries). During relative sea-level fall, percolation of meteoric waters through sandstones of the LST and below sequence and parasequence boundaries resulted in extensive dissolution of detrital grains and formation of kaolinite, authigenic K-feldspar and feldspar overgrowths as well as formation of mechanical infiltrated clays around the detrital grains. During relative sea-level rise, invasion of marine water into the sandstones as a consequence of landward migration of the shoreline, as well as low sedimentation rates encountered in the TST, resulted in the formation of glauconite, apatite and pyrite. Development of pseudomatrix, which was formed by mechanical compaction of mud intraclasts, is mostly abundant along transgressive surfaces and parasequence boundaries of the TST, and is related to the abundance of mud intraclasts in the transgressive lag deposits.The types and extent of eogenetic alterations have an important impact on the distribution of the mesogenetic alterations, including the formation of quartz overgrowths and dickite.Distribution of mesogenetic quartz overgrowths in the sandstones was controlled by the distribution of mechanically infiltrated clays and the presence of eogenetic cement. Sandstones that remained poorly cemented during eodiagenesis and that have thin or discontinuous infiltrated clay rims around the detrital grains were cemented during mesodiagenesis by quartz. The absence of extensive eogenetic cements in the sandstones suggested that the partial deterioration of porosity was mainly due to mechanical compaction. Partial transformation of kaolinite to dickite, which indicates neomorphic change to a better-ordered and more stable crystal structure at the elevated temperatures during mesodiagenesis, is partially a function of distribution of kaolinite during eodiagenesis.The conceptual model developed in this study shows the diagenetic evolutionary pathways in the reservoir sandstones within a sequence stratigraphic context, which in turn provides some insights into the controls on reservoir heterogeneity.  相似文献   

Hydrogeochemical investigations of thermal waters in the northeastern part of Morocco     

A. E. Barkaoui  Y. Zarhloule  A. Rimi  M. Verdoya  S. Bouri 《Environmental Earth Sciences》2014,71(4):1767-1780

Northeastern Morocco is characterised by a large number of surface geothermal manifestations. Thermal waters are hosted within sedimentary rocks, and in particular the Liassic dolomitic limestones act as a reservoir. The presence of geothermal waters is closely related to important fault systems. Meteoric water infiltrates along those fractures and faults, gets heated, and then returns to the surface through hydrothermal conduits. Most of the thermal waters are of Na–Cl and Ca–Mg–HCO₃ types. In this paper different geochemical approaches were applied to infer the reservoir temperature. Na–K–Mg^1/2 ternary diagram points to temperatures ranging from 100 to 180 °C. Cation geothermometers suggest an average reservoir temperature of about 100 °C. Mineral solution equilibria analysis yields temperatures ranging from 50 to 185 °C. The silica enthalpy mixture model gives an average value (about 110 °C) higher than that inferred from cation geothermometers.  相似文献   

Exploration of new gold occurrences in the alteration zones at the Barramiya District,Central Eastern Desert of Egypt using ASTER data and geological studies   总被引：1，自引：1，他引：0  

S. M. Salem  N. M. Soliman  T. M. Ramadan  R. O. Greiling 《Arabian Journal of Geosciences》2014,7(5):1717-1731

The use of ASTER data and fieldwork supported by mineralogical and geochemical analyses enabled exploration of new gold occurrences in the alteration zones in the ultramafic–mafic successions at the Barramiya district. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) band ratios (4/8, 4/2 and 8/9 in R, G and B channels, respectively) helped in recognising of two listwaenite alteration zones (areas 1 and 2) promising for gold in the north-east and south-east of the Barramiya gold mine. Mineralogical studies and X-ray diffraction analysis revealed that areas 1 and 2 are characterized by variable concentrations of talc, ankerite, magnesite, quartz and calcite. Ore microscope studies revealed the sulphide minerals carry gold within these alteration zones; moreover, goethite and malachite are also observed. Fire assay results show Au contents in the range of 5.04 ppm in the graphite schist, 4.02 ppm in the quartz veins and 3.76 ppm in the listwaenite alteration. The atomic absorption analysis (AAS) of samples from area 1 yields an average Au content in the quartz-veins of 2.4 ppm, Ag content is 8.0 ppm and Cu content is 2.4 wt%. The listwaenite alteration gives an average Au content of 4.4 ppm and a Cu content of 2.8 wt%. In area 2, the AAS of the quartz-veins revealed an average Au content of 2.6 ppm, 6.2 ppm Ag and 1.9 wt% Cu. The listwaenite alterations of area 2 grade 3.5 ppm Au and 2.4 wt% of Cu. The Barramiya District is made up of ophiolitic ultramafic belts of serpentinites, talc carbonates and talc graphite schists, mainly thrust over the metavolcanic sequences. They include highly strained and tectonised parts enriched in sulphides, iron oxides and carbonates, with developed listwaenite alterations along the thrust contacts. Gabbro and granitic intrusions were intruded in the ultramafics and metavolcanic rocks. ASTER data are an accurate and helpful tool for detecting and mapping alteration zones for gold exploration.  相似文献   

Exploration of copper deposits in Wadi El Regeita area, Southern Sinai, Egypt, with contribution of remote sensing and geophysical data     

S. M. Salem  Sultan Awad Arafa  T. M. Ramadan  El Sayed A. El Gammal 《Arabian Journal of Geosciences》2013,6(2):321-335

Three types of hydrothermal alterations are recorded in Wadi El Regeita area, argillic, phyllic, and propylitic. Whole-rock analysis of representative samples of the alteration halo (1) shows a Cu, Au, and Ag content up to 1.7 wt.%, 1.6 g/t, and 4 g/t, respectively; in the alteration halo (2), these metal contents are up to 1.3 wt.%, 1.4 g/t, and 3 g/t, following the same order. The integrated remote sensing and geophysical data, as well as geological field verification, show that Wadi El Regeita area includes promising Cu ores within two hydrothermal alteration haloes. Spatial data analyses of lineaments from Landsat Enhanced Thematic Mapper (ETM) band ratio image (7/5, 5/4, 3/1) reveal the presence of alteration haloes that potentially may host Cu mineralization at south and north of El Regita Cu mine. Gravity interpretation indicates that the surveyed area is dissected by NE–SW fault zones in the central part, near Wadi El Regeita Cu mine. Ground magnetic survey data revealed that the surveyed area includes six magnetic bodies at depths ranging from 32 to 90 m, possibly recording the presence of mineralized and hydrothermally altered andesitic dykes. The half length of these dykes ranges from 600 to 1,070 m; their half thickness from 30 to 123 m and their half width from 48 to 531 m. Dyke locations coincide with surface alteration haloes (1) and (2) as indicated by the ETM band ratio image processing. The final assessment of the area, however, needs more detailed geological and geophysical studies with contributions of remote sensing techniques.  相似文献   

Implementation and evaluation of multivariate analysis for groundwater hydrochemistry assessment in arid environments: a case study of Hajeb Elyoun–Jelma, Central Tunisia     

Soumaya Hajji Kolsi  Salem Bouri  Wafik Hachicha  Hamed Ben Dhia 《Environmental Earth Sciences》2013,70(5):2215-2224

In most arid zones, groundwater (GW) is the major source of domestic, agriculture, drinking, and industrial water. Accordingly, the monitoring of its quality by different techniques and tools is a vital issue. The purpose of this paper is the evaluation of the combination of principal components analysis (PCA) and geostatistics as a technique for (1) identifying the processes affecting the groundwater chemistry of the detrital unconfined Middle Miocene Aquifer (MMA) of the Hajeb elyoun Jelma (HJ) aquifer (Tunisia) and (2) mapping the controlling variables for groundwater quality. This work is based on a limited database recorded in 22 wells tapping the aquifer and unequally distributed in the field. The proposed approach is carried out in two steps. In the first step, the application of PCA revealed that rock–water interaction, agriculture irrigation and domestic effluents could explain 85 % of the observed variability of the chemical GW quality of the MMA. As a result, two new variables are defined: V1 (rock–water interaction influence) and V2 (irrigation and domestic effluent influence). In the second step, the spatial variability of these variables over the extent of the MMA is mapped by applying a kriging interpolation technique. The results of this study suggest that, while both natural and anthropogenic processes contribute to the GW quality of the MMA, natural impacts can be considered as the most important.  相似文献   

Properties of geothermal resources in Kebilli region, Southwestern Tunisia   总被引：2，自引：2，他引：0  

Fatma Ben Brahim  Jalila Makni  Salem Bouri 《Environmental Earth Sciences》2013,69(3):885-897

The Kebilli region is located in the Southwestern part of Tunisia, and is characterized by the presence of deep and shallow geothermal systems (continental intercalary and complex terminal). Chemical and isotopic contents are used to classify the type and determine the origin of thermal water. An evaluation of reservoir temperature and a possible geothermal fluid mixing are also carried out. Both continental intercalary-deep aquifer and complex terminal-shallow aquifer are of Na–(Ca)–Cl–(SO₄) mixed water type. The use of different geothermometers and the computation of saturation indexes for different solid phases suggests that the thermal reservoir temperature of the continental intercalary is between 92 and 105 °C, while the fluid temperature from the shallow complex terminal aquifer ranges from 50 to 75 °C. Also, the isotopic data indicates the old origin of all groundwater of Southwestern Tunisia. Mixing effects characterizing the continental intercalary and the complex terminal aquifers were identified using δ²H and δ¹⁸O relationship. It appears that the upward movement of thermal water from the deep aquifer to shallow ones is probably due to the abundant fractures in the research area.  相似文献   

Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus)     

Kenneth F. Rijsdijk  Julian P. Hume  Frans Bunnik  F.B. Vincent Florens  Claudia Baider  Beth Shapiro  Johannes van der Plicht  Anwar Janoo  Owen Griffiths  Lars W. van den Hoek Ostende  Holger Cremer  Tamara Vernimmen  Perry G.B. De Louw  Assenjee Bholah  Salem Saumtally  Nicolas Porch  James Haile  Mike Buckley  Matthew Collins  Edmund Gittenberger 《Quaternary Science Reviews》2009,28(1-2):14-24

Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths). With >250 bone fragments/m² and comprising 50% of all known extinct and extant vertebrate species (n_s = 44) of Mauritius, MAS may constitute the first Holocene vertebrate bone Concentration-Lagerstätte identified on an oceanic volcanic island. Fossil remains are dominated by extinct giant tortoises Cylindraspis spp. (63%), passerines (～10%), small bats (7.8%) and dodo Raphus cucullatus (7.1%). Twelve radiocarbon ages [four of them duplicates] from bones and other material suggest that accumulation of fossils took place within several centuries. An exceptional combination of abiotic conditions led to preservation of bones, bone collagen, plant tissue and microfossils. Although bone collagen is well preserved, DNA from dodo and other Mauritian vertebrates has proved difficult. Our analysis suggests that from ca 4000 years ago (4 ka), rising sea levels created a freshwater lake at MAS, generating an oasis in an otherwise dry environment which attracted a diverse vertebrate fauna. Subsequent aridification in the south-west Indian Ocean region may have increased carcass accumulation during droughts, contributing to the exceptionally high fossil concentration. The abundance of floral and faunal remains in this Lagerstätte offers a unique opportunity to reconstruct a pre-human ecosystem on an oceanic island, providing a key foundation for assessing the vulnerability of island ecosystems to human impact.  相似文献   

An “Olympic” framework for a green decommissioning of an offshore oil platform     

Salem Y. Lakhal  M.I. Khan  M. Rafiqul Islam 《Ocean & Coastal Management》2009,52(2):113-123

Oil and gas offshore platform and installations have a limited life of operations. When oil runs out, many terms are used to describe the situation: abandonment, removal, disposal, decommissioning, etc. Even the issue of decommissioning is now at the forefront of deep water oil drilling for many reason (the enormous costs required for disposal, the increasing number of rigs which required removal, the need to protect the marine environment, legal frameworks), there are very few published researchers studying the problem according to its different facets (legal, environmental, economical etc.). In this paper, we apply the concept of “Olympic” supply chain developed by Lakhal et al. Lakhal, SY, H'Mida S, Islam R. Green Supply Chain parameters for a Canadian Petroleum Refinery Company. International Journal of Environmental Technology and Management, IJETM 2007:7;56–67. to provide feedback for life-cycle offshore platforms. Our approach starts from platform development projects environmentally, exploit it in the respect of the environment and have an efficient decommissioning project.  相似文献   

A thirty-year artificial recharge experiment in a coastal aquifer in an arid zone: The Teboulba aquifer system (Tunisian Sahel)   总被引：1，自引：0，他引：1  

Salem Bouri  Hamed Ben Dhia 《Comptes Rendus Geoscience》2010,342(1):60-74

With the increased demand for groundwater resulting from fast demographic growth, accelerated urbanization, economic and agricultural activity diversification, and the increase of per capita consumption, ground water resources, in particular in coastal regions, remain relatively low, compared to demand. The groundwater quality and piezometric variations result mainly from intensive exploitation, agricultural activities and the intrusion of seawater. This phenomenon is observed mostly in semi-arid areas, such as the oriental Sahel of Tunisia, where an apparent reduction in rainfall in recent years can be seen. Groundwater becomes overexploited especially as its natural recharge by rainwater does not succeed in maintaining the hydrologic balance. The imbalance between water demand and resources induces the degradation of the water quality. In such a case, the artificial recharge of water-table aquifers by water from dams is a credible alternative to improve the hydrodynamic and physicochemical conditions of the groundwater. Like most coastal aquifers, the Teboulba water-table aquifer is threatened by overexploitation for at least three decades. This threat appears by a considerable piezometric level drop and by water salinisation, due to seawater intrusion. Given this alarming situation, since 1971, artificial recharge through wells with surface water from a dam was tested in order to restore the water levels and to improve water quality. The piezometric and chemical surveys of the Teboulba aquifer permitted one to describe the temporal and spatial piezometric and geochemical conditions of the aquifer and to show the effect of the artificial recharge. Indeed, the artificial recharge undertaken since 1971 made the geochemical and piezometric conditions of the Teboulba aquifer improve. This example is a rare, well-documented case-study of the benefits of artificial recharge in a coastal aquifer, over the long term.  相似文献