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1.
Zinc–lead–barite deposits located in Lefan and Lower Banik localities of about 25 km northeast of Zakho City, Northern Iraq
consist of a group of strata-bound sulfides hosted in Upper Cretaceous (Upper Campanian–Maastrichtian) dolomitic limestone.
Carbonate-hosted ores contain 3.77% Zn, 2% Pb, and 5% Fe, while in lower Banik, they contain 1.5% Zn, 0.37% Pb, and 1.4% Fe.
Diagenetic processes, such as dolomitization and recrystalization in addition to the type of microfacies, provided appropriate
physical and chemical conditions that permitted the passage of ore-bearing fluids and participated in precipitation and ore
localization. These deposits are precipitated in a platform and developed within the Foreland Thrust Belt. Ore precipitated
as infill of intergranular dolomite porosity with replaced dolomite and rudist shells forming disseminated crystals that occupy
intergranular pore spaces around dolomite and calcite and as infill of dissolution spaces and fractures. 相似文献
2.
The origin of the Serguza lead-zinc deposit of the Northern Thrust Zone has been suggested to be epigenetic, hydrothermal, structurally controlled by a post Tertiary major fault zone. Reinterpretation of previously obtained data and the evaluation of the present results have provided enough evidence to argue for a different mode of formation. Based upon trace element content of the ore minerals, dating of galena, ore and country rock texture, and the results of the detailed geochemical and geophysical prospecting in the area, it seems that the deposit is strata-bound, stratigraphically controlled within the Triassic dolomites. Its simple mineralogy, chemistry, and other features are comparable with other early Alpine strata-bound leadzinc deposits of the Mediterranean Belt. 相似文献
3.
Mineralium Deposita - Bedded marine sedimentary phosphate rocks of Campanian-Maastrichtian age are exposed in the Western Desert of Iraq, forming part of the Tethyan phosphate province. The studied... 相似文献
4.
The Hussainiyat ironstone deposit (Jurassic) is mainly pisolitic, intraclastic and concretionary in texture, associated with
kaolinite mudstones and/or with quartzose sandstone. The ironstone consists mainly of goethite, hematite, kaolinite and quartz.
The deposits were derived from a variety of parent rocks that included low- and medium-rank metamorphics, intermediate igneous
rocks and pre-existing sediments of the Nubio-Arabian Shield. The source rocks suffered deep chemical weathering in the hinterland,
and the products (Fe-oxyhydroxides, kaolinite and quartz) were later transported by rivers to the depositional site. Iron
was mostly carried in association with the clay fraction and organic matter. Several genetic processes were involved in the
ironstone formation. Iron concretions were mostly formed by bacterial build-up in swamps and marshes, and were subsequently
embedded in kaolinitic mud. Large-scale development of groundwater laterite blanket (ferricrete) occurred later in the overbanks
and floors of wadis, under oxidizing pedogenic conditions. During this stage iron was mobilized from the kaolinitic deposits
and migrated upward in dry seasons and, to a lesser extent, downward in wet seasons. Pisolites and oolites grew in situ in
the kaolinitic soil at the upper limit of the fluctuating water table. This ferricrete blanket had a wide and continuous extension
within an elongated paleodepression. Seasonal heavy rain periods resulted in the flow of ephemeral streams and rivers, where
major parts of this ferricrete was reworked and deposited with quartz sand and mud clasts as channel deposits. The original
pisolitic-colloform ironstone was reworked continuously to form a semi-continuous sheet. In such wet seasons, additional Fe-enrichment
took place as cementing materials or overgrowths.
Received: 28 April 1995 / Accepted: 10 July 1997 相似文献
5.
Application of a revised hydrostratigraphical classification and nomenclature to the Mesozoic and Cenozoic succession of Saudi Arabia 总被引：1，自引：0，他引：1
Abdulaziz M. Al-Bassam Mohammed E. Al-Dabbagh Mohammed Tahir Hussein 《Journal of African Earth Sciences》2000,30(4):917
At the dawn of the 21st century many parts of the world are suffering a shortage of water resources. Arid and semi-arid areas in particular are facing challenges and increasing pressure is being put on their groundwater management plans. Such a situation created an urgent need to put forward a design for classification and nomenclature that can help to differentiate highly productive zones from small locally exploited productive zones. A previously proposed hydrostratigraphical classification and nomenclature scheme is revised, modified, and applied to the Mesozoic-Cenozoic sedimentary succession of Saudi Arabia. The scheme utilised in the present paper is modified to include, in addition, productivity, water quality criteria, usability, and recharge as criteria reflecting the hydrogeological importance of the productive zones.The Triassic Sudair Mega-aquitard forms the lower hydrostratigraphic boundary for the Ad-Dahna'a Aquasystem. The Ad-Dahna'a Aquasystem comprises two aquagroups: the Riyadh and Rub'Al-Khali Aquagroups. Each aquagroup is in turn subdivided into superaquifers, aquifers and possibly subaquifers, separated by aquitards of different ranks. The physical and hydrogeological characteristics of each unit are also discussed. 相似文献
6.
Despite the need of stratigraphers and hydrogeologists for a hydrostratigraphical classification, such widely accepted classification is lacking and was ignored by the 1983 code of the North American Commission on Stratigraphical Nomenclature (NACSN). This study is an attempt to fill this vacuum. A simple and universally applicable hydrostratigraphical classification scheme is introduced here which takes into consideration the physical properties of the rocks, especially porosity and permeability, in addition to other variables such as thickness of the unit and its areal extent.The proposed hydrostratigraphical classification is a hierarchical scheme composed of two types of hydrostratigraphical units: aquizones and aquitards, which differ significantly in their intrinsic permeabilities. Aquizones include five ranks which are named in ascending order: subaquifer, aquifer, superaquifer, aquagroup and aquasystem. The aquifer is the fundamental unit. Aquitards are divided into mini-aquitards, meso-aquitards and mega-aquitards differing in their thicknesses and lateral continuities. Hydrostratigraphical units are easier to recognise on geophysical logs than lithostratigraphical units; they have fewer boundaries and therefore, it is easier for hydrogeologists to identify them.To test the applicability of the proposed classification the Palaeozoic succession of Saudi Arabia has been chosen to illustrate such an application. The stratigraphical interval between the Precambrian Arabian Shield aquifuge below and the Lower Triassic Sudair mega-aquitard above is named here the Najd Aquasystem, whose boundaries largely coincide with those of the Palaeozoic Erathem. The Najd Aquasystem, in turn, is divided into two aquagroups called the Buraydah below and the Widyan above and separated by the 600 m-thick Qusaiba Mega-aquitard.The Buraydah Aquagroup is composed of two superaquifers: the Saq and the overlying Hail, whereas the Widyan Aquagroup is divided into two superaquifers named the Jalamid below and the Rafhah above. Each of these superaquifers is composed of two named aquifers separated from each other by aquitards of different ranks. the hydrogeological characteristics of each aquifer were briefly discussed. 相似文献
7.
Khaldoun S. Al-Bassam 《Meteoritics & planetary science》1978,13(2):257-265
The Alta'ameem hypersthene chondrite is a light gray brecciated and metamorphosed meteorite composed mainly of olivine (27% Fa), orthopyroxene (24.5% Fs) and plagioclase (An10). Other minerals include troilite, kamacite, taenite, chromite, ilmenite, clinopyroxene, chalcopyrite, and apatite or merrillite. The mineralogical and chemical analyses suggest that the Alta'ameem meteorite belongs to the amphoterite group of chondrites. The chemical composition includes the following: Fe 3.39, Ni 1.13, Co 0.05, Cu 0.01, FeS 6.48, SiO2 39.48, TiO2 0.28, Al2O3 2.25, FeO 16.46, MnO 0.40, MgO 25.66, CaO 1.47, Na2O 1.05, K2O 0.15, P2O5 0.47, Cr2O3 0.45; total 99.18. 相似文献
8.
Almadani Sattam Abdelrahman Kamal Ibrahim Elkhedr Al-Bassam Abdulaziz Al-Shmrani Awad 《Arabian Journal of Geosciences》2015,8(4):2347-2357
Arabian Journal of Geosciences - Microtremor horizontal-to-vertical spectral ratio (HVSR) method has been conducted at 33 sites in Ahud Rufeidah urban expansion zone in order to assess the... 相似文献
9.
Sawsan M. Ali Balsam S. Al-Tawash Khaldoun S. Al-Bassam 《Arabian Journal of Geosciences》2014,7(5):1811-1827
Baghdad City is characterized by high population density and wide variation in land use. It is covered by Quaternary flood plain deposits of variable nature where silt is the predominant component. The shallow aquifer is unconfined to semi-confined at some locations. The hydraulic properties of the aquifer are highly variable in the study area. A study of this groundwater shallow aquifer and the hydrochemical relation with the Tigris River were conducted using geochemical modeling approach. Baghdad Meteoric Water Line (BMWL) was also constructed using data of stable isotopes of hydrogen and oxygen. The hydrochemical parameters of the Tigris River show significant differences at high and low flow conditions, and there are clear difference among the selected stations. Groundwater parameters show also significant spatial and temporal variations in major and minor elements concentrations. Geochemical modeling results indicate that dissolution of dolomite, gypsum, chlorite, siderite, chalcedony, cation exchange of Ca2+/Na+ and precipitation of calcite, illite, kaolinite, and hematite are the main chemical reactions in the Rasafa side, whereas no specific reactions can be shown in the Karkh side. Mixing models of the shallow groundwater and Tigris River water show various patterns affected by other factors such as the aquifer recharge and evaporation, especially at the most shallow parts. The BMWL has been defined by the equation $ {\delta^2}\mathrm{H} = 8.6\ {\delta^{18}}\mathrm{O} + 17.48 $ and the stable isotopes of hydrogen and oxygen reveal different signatures in the Karkh and Rasafa sides, where clear zonation at Rasafa can be observed. We conclude that recharge water undergoes significant evaporation through its transit to the aquifer. 相似文献
10.
Water samples from 72 wells tapping the Jilh aquifer were collected and analyzed for 10 different water quality parameters. Using these data, a regional irrigation water quality was assessed using three techniques: (i) United States Department of Agriculture method (USDA), (ii) Food and Agriculture Organization (FAO) guidelines for water quality assessment, and (iii) Water-Types approach. The USDA method revealed that the aquifer water salinity, as represented by electrical conductivity, ECw, ranges from high salinity (C3: ECw > 0.75–2.25 dS/m) to a very high salinity (C4: ECw > 2.25 dS/m). The sodium adsorption ratio (SAR) varied from low (S1) to very high (S4) sodicity. Therefore, the water of the Jilh aquifer is dominantly of the C4–S2 class representing 56% of the total wells followed by C4–S1, C4–S3, C3–S1 and C4–S4 classes at 19%, 14%, 8%, and 3% of the wells respectively. The FAO system indicated moderate to severe restriction on the use for irrigation and slight to moderate ion toxicities for Na+, Cl−, B+, NO3− and HCO3−. It is clear that, both USDA and FAO systems condemn the Jilh groundwater as hazardous for irrigation due to its high salt content, unless certain measures for salinity control are undertaken. The dominant salt constituents in the water are Mg–Cl2, Na–Cl and Ca–Cl2 as per the Water-Types method. However, due to the complexity in classifying the aquifer groundwater for irrigation, a simplified approach acknowledging three class groups (I-suitable water, II-conditionally suitable water and III-unsuitable water) adopted from the three methods, is suggested in this paper. The simplified approach combines C–S classes of the USDA method among these three groups according to the lowest ratings. The salinity of the FAO method has been split arbitrarily into slight and moderate subclasses with values of 0.7–2.25 and >2.25 dS/m, respectively; to match with the C3-class of the USDA system. The Water-Types were classified assuming that Ca–Cl2 is the least hazardous salt, followed by Mg–Cl2 and Na–Cl. Using this integrated hydrochemical method, the majority of the wells (92%) contain unsuitable water for irrigation (Group III) while the remaining wells (8%) are in Group II with water considered conditionally suitable for irrigation. 相似文献