Ferruginous Sandstone Research Articles

Carcinogenic and Non-Carcinogenic Health Risk Evaluation of Heavy Metals in Water Sources of the Nubian Sandstone Aquifer in the El-Farafra Oasis (Egypt)

Expanding anthropogenic activities, globally and in Egypt, have increased concentrations of heavy metals in surface and ground waters. Contamination of drinking water may threaten public health. In the present study, the concentrations of 10 heavy metals were analyzed from natural springs (6) and drilled wells (10) in the Nubian Sandstone Aquifer of the El-Farafra Oasis and the White Desert National Park, Egypt. The average concentrations of heavy metals were in most cases below critical values of the WHO drinking water standard, except for Fe and Mn (average values were 495 and 107 µg·L−1, respectively). There is a surface circulation that develops within limestone (Post-Nubian Aquifer System—PNAS) and feeds the springs, while the water present in the wells (at least for the deeper ones) comes from the ferruginous sandstone (Nubian Sandstone Aquifer System—NSAS). This double circulation could account for the differences in the EC and TDS values (typical of a circulation in limestone-type aquifers for springs) and the Fe and Mn enrichment coming from the ferruginous sandstone of the NSAS. The average chronic daily intake (CDI) values for heavy metals in the study area are listed in decreasing order in the following: Fe > Mn > Zn > Co > Ni > Cr > As > Pb > Co > Cd. The total hazard quotient (HQtotal = HQoral + HQdermal) and Hazard Index (HI) values calculated for different heavy metals were well below the acceptable limit, indicating no significant non-carcinogenic health risks to the residents of both areas via oral and dermal absorption of drinking water. Furthermore, the results obtained for the total risk to human health showed that oral ingestion is the major pathway. Carcinogenic risk analysis indicated that the Incremental Lifetime Cancer Risk (ILCR) values for Pb, Cd, Ni, and Cr were well below the acceptable limits.

Formation of Brahmani Natural Arch, Eastern India: A proposed geoheritage site of India

Natural arch is one of the most fascinating geomorphological features formed by erosional process and many of them are formed within gently dipping sandstone. A natural arch (Location: 21°54′32.20″ N, 83°43′46.20″ E, RL: ∼370 m) of such type is present in the rocks of Upper Kamthi Formation of Middle Jurassic age (160–184 Ma), Upper Gondwana Group, Ib River Coalfield within dense Chhengapahar Reserve Forest near Brahmani Village, Sundargarh District, Odisha. This oval shaped natural arch with a maximum length and height of ∼30 m at the base and ∼12 m respectively. The alcove of the natural arch has maximum height and width of ∼7 m and ∼15 m respectively, is opened along NE-SW direction on the top of the hill. Flesh red colored, ripple topped, trough to planar cross stratified, coarse to gritty, texturally and mineralogically immature, ferruginous sandstone of Upper Kamthi Formation forms the hill. Kaolinisation of feldspathic members makes the sandstone loose and porous. Two orthogonal set of faults-joints (130°/60°W and 40°/60°E) initiated the formation of natural arch while the porosity of the immature, arkosic sandstone accelerate the process through subaerial weathering where surface/rain water percolation–temperature fluctuation played effective roles. Therefore, the formation of natural arch is a result of structurally triggered weathering and erosion. Efforts have already been taken to preserve this place as national geo-heritage site by Geological Survey of India, Government of India.

Petro-geochemical Signatures as Evidences for Tectonic Setting, Palaeoweathering and Provenance of Eocene Kopili Sandstones, Meghalaya, Northeast India

Abstract Spectacularly preserved yet least studied middle to late Eocene Kopili Formation in parts of East Jaintia Hills district, Meghalaya has been documented to understand the provenance, tectonic setting and palaeoweathering employing petrological and geochemical attributes. The Kopili Formation is characterized by alternations of fossiliferous marl-splintery grey to black shale-siltstone and fine to medium grained ferruginous sandstone with occasional coal streaks. Petrographically, Kopili sandstone has been grouped into two categories i.e. subarkose and sublitharenite. Geochemically, Kopili sandstone possesses high SiO2 and relatively low Al2O3 and Fe2O3 confirming to the modal composition Q72.70 F6.57 RF7.01 CT3.12 Mx2.28 M2.07 HM1.82. These are quartz-rich (SiO2 75.96%) clean sandstone depicting strong negative correlation of SiO2 with rest of the major oxide except for CaO which is relatively weak. High SiO2 is in conformity with quartz enrichment (73.50%), does indicate a passive (atlantic type) continental margin set up for the deposition of Kopili Formation. Neo-development of quartz and feldspar in parts reflect high degree of diagenesis. Chemical indices like CIA, CIW, PIA and ICV reveal intense weathering under semi-arid to semi-humid climatic conditions. Besides minor contributions from continent interior, sediments were largely derived from recycled orogen involving rhyolitic / granitic sources containing plagioclase feldspars in the range of An0-An70 as evident from geochemical attributes.

Extraction of uranium and rare earths from mineralized ferruginous sandstone, southwestern Sinai

Abstract A technological sample assaying 943 ppm U and about 0.97 % RE2O3 in a mineralized ferruginous sandstone has been collected from Wadi Sedri area of southwestern Sinai. The XRD analysis has releaved the presence of uranium minerals namely; coffinite and sodium meta-autonite but the rare earths adsorbed on the clay minerals inter the ore sample. Leaching of uranium and rare earths from the studied sample is based on ferric sulfate salt. The relevant conditions e.g. (6 g/L ferric sulfate concentration, 1/5 S/L ratio, time 8 h, T = 80 °C and 7.5 g/L H2SO4 concentration) of the ferric ion leaching for uranium and rare earths have been optimized. From the obtained leach liquor, the rare earths are precipitated as oxalates. This is followed by uranium recovery using anion exchange resin as impregnated Lewatite Monoplus M 500/Alamine 304. Therefore, highly pure products of uranium and rare earths have been obtained and chemically analyzed.

Delineation of groundwater potential zones in northern Omdurman area using electrical resistivity method

This study is conducted in the northern Omdurman area to delineate groundwater potential zones using electrical resistivity method. Omdurman is the most ancient city known as the historical capital of Sudan. Geoelectric survey employing vertical electrical sounding (VES) technique is carried out to explore the availability of groundwater in the study area. The measurements were conducted using Schlumberger configuration. In this study, twelve VES points are measured along four profiles. The measured data is processed and interpreted using 1D geophysical inversion technique constrained by lithological data obtained from two boreholes. The integration of electrical and geological data led to a reliable interpretation of the geophysical model. The obtained results revealed that the geological succession of the study area is mainly composed of five layers of recent deposits, clay, sandy clay, silicified and ferruginous sandstone, and sandstone. According to the resulting hydrogeological sections, the water-bearing formation is composed mainly of coarse sandstone and varies in thickness under confined conditions. The geoelectrical sounding method successfully fulfilled the aims of the study. Nevertheless, detailed hydrogeological and geophysical investigations need to be carried out for a comprehensive characterization of the groundwater aquifer.

Assessment of the Nubian aquifer characteristics by combining geoelectrical and pumping test methods in the Omdurman area, Sudan

The recent research is carried out to model the characteristics and productivity of the groundwater aquifer in the Omdurman area, Sudan, by combining electrical resistivity and pumping test methods. Omdurman is the most populous city known as the traditional capital of Sudan. Vertical electrical sounding (VES) survey using Schlumberger array is carried out along four profiles to delineate the potential groundwater zones. Application of 1D geophysical inversion revealed five geoelectric layers, including recent deposits, clay, silicified and ferruginous sandstone, and sandstone. Additionally, based on the outcome of VES inversion, Dar Zarrouk parameters, including transverse resistance and longitudinal conductance, were calculated to model the aquifer characteristics. The transverse resistance ranged from 5587 to 309,853 Ωm2, while the longitudinal conductance varied between 0.14 and 2.5 Ω−1. The hydraulic conductivity and transmissivity are further measured using the VES data, ranging from 1.4 to 5.2 m/d and 435 to 1564 m2/day, respectively. The step-drawdown pumping tests were performed to evaluate the aquifer characteristics and thus validate the result of the geoelectrical method. The transmissivity obtained from the step test varied between 583 and 1226 m2/day, showing an acceptable agreement with those of geoelectrical data. Based on the measured parameters, the aquifer is classified as highly productive and ideal for groundwater development. The step drawdown test was further used to assess the performance of groundwater wells. The results indicated that faulty well design and inappropriate pumping rates influence some wells in the study area, resulting in high drawdown and low well efficiency. Overall, the objectives of the study were successfully achieved; nonetheless, detailed hydrogeological and geophysical investigations are recommended for comprehensive evaluation of the groundwater aquifer.

The Upper Cretaceous elasmobranch fauna from Senegal

Three successive horizons were sampled by bulk-sampling across the Campanian–Maastrichtian marine succession at the Cap de Naze cliff, South of Popenguine, Senegal. The material collected includes several hundreds of elasmobranch micro-remains as well as surface-collected specimens that are described in the present work. Twenty-six species are recorded, including three new genera and eight new batomorph species (Ptychotrygon nazeensis sp. nov., Terangabatis thiami gen. et sp. nov., ‘Rhinobatos’ popenguinensis sp. nov., Atlantobatis acrodonta gen. et sp. nov., Sowibatos minimus gen. et sp. nov., ‘Dasyatis’ reticulata sp. nov., Coupatezia casei sp. nov., Phosphatodon cretaceus sp. nov.). These new samplings complement previous records based on surface collection of the Cape de Naze section and bring the number of elasmobranch species for this fauna to 31. Increasing elasmobranch taxonomic diversity throughout the three successive assemblages indicates a transition from restricted marine to open coastal settings. This high-diversity fauna is dominated by necto-benthic batomorphs and is similar in its structure to other Tethyan and Eastern Atlantic Maastrichtian faunas. The high number of species apparently endemic to the studied area suggests high habitat differentiation in corresponding marine Maastrichtian settings. The presence of typical Maastrichtian species in the top of Unit 1 argues against a Campanian age previously proposed for this unit, while our data support a middle–late Maastrichtian age for the ferruginous sandstone bed of Unit 3.

New Late Cretaceous titanosaur sauropod dinosaur egg clutches from lower Narmada valley, India: Palaeobiology and taphonomy.

The Upper Cretaceous (Maastrichtian) Lameta Formation is well-known for its osteological and oological remains of sauropods from the eastern and western parts of the Narmada Valley, central India. The newly documented ninety-two titanosaur clutches from Dhar District (Madhya Pradesh State, central India) add further to this extensive data. Previously parataxonomy of these titanosaur clutches was carried out with a few brief reports on palaeobiological and taphonomic aspects. The quantitative data collected from the new clutches (this study) opens avenues to additionally understand more about titanosaur palaeobiology and to qualitatively understand preservation and taphonomical aspects of their egg clutches. Herein, we document 256 eggs and three clutch patterns (viz. circular, combination, linear) that are assignable to six oospecies. The high oospecies diversity points to a possible high diversity in titanosaur taxa in the Indian sub-continent though it is not reflected in titanosaurid body fossils. All the macro- and micro-structures helped in understanding egg deformation and preservation from a taphonomic point of view. Additionally, a pathologic egg documented from the study area helped in understanding the reproductive biology of titanosaurs, such as the possibility of segmented oviduct and sequential laying of eggs by titanosaurs. In addition, we made an attempt to infer aspects such as egg burial, absence of parental care, colonial nesting behavior. All the egg clutches were observed within sandy limestone and calcareous sandstone lithologies that occur in scattered outcrops with rocks showing floating siliciclastic grains in a micritic groundmass. Further, the presence of ferruginous sandstone in the Jamniapura and Padlya regions (Dhar District, central India) is indicative of a possible alluvial/fluvial setting. The presence of grainy intraclastic fabric, alveolar-septal fabrics, brecciation and shrinkage cracks observed in the clutch-bearing rocks are indicative of a low energy-low gradient palustrine depositional condition in a fluvial/alluvial setting. Finally, we envisage that a few egg clutches of this area were laid close to lake/pond margins while most were laid away from the lake/pond margins, and thus, were hatched.

Comparative evaluation of chemical and bio techniques for uranium leaching from low grade sandstone rock sample, Abu Thor, southwestern Sinai, Egypt

Ferruginous sandstone considered as a one of the economically significant uranium mineralized areas in the southwestern part of the Sinai that located at the lower member of Um Bogma Formation in Abu Thor area. The studied sample was characterized geologically as a sandstone rock contain 450 mg/kg of uranium. This work is aimed to compare between eco-friendly bioleaching and conventional leaching processe. The uranium bioleaching efficiency achieved 80% by using a native fungal strain; Aspergillus nidulans as a green technology with the optimimum conditions as; 3 pH value, 3% pulp density, 7 days incubation period, and 30 °C incubation temperatures. Whereas the traditional technique using alkaline and sulphuric acid leaching attained 68.5% and 95% respectively at the best condition. Finally, the shrinking core model was represented the layer diffusion process by acquiring apparent activation energy 18.28 and 16.82 kJ/mol for carbonate and sulphuric acid leaching, respectively.

LITHOSTRATIGRAPHIE ET SEDIMENTOLOGIE DES FORMATIONS SEDIMENTAIRES DE TIAPOUM, SUD-EST DE LA COTE D IVOIRE : IMPLICATION PALEOENVIRONNEMENTALE

Tiapoumdepartment is located in the southeast of the onshore basin of Cote dIvoire. The sedimentological, granulometric and morphoscopic analyzes carried out on 24 samples from two wells made it possible to determine the lithological, granulometric and paleoenvironmental evolution of the sediments of this area. The lithological characterization of the sediments revealed four lithological facies in the department of Tiapoum. We therefore have in the direction of sedimentation, a thick layer of clay-sandy, sands intercalated with ferruginous sandstone absent at Aby crossroads and the land of the bar which thins from upstream to downstream. As for the particle size analysis, it reveals that the sands of the department of Tiapoum were deposited by free accumulation. These are well to very well graded sands with a predominance of medium grains with an asymmetry towards the fine grains. They were deposited in a fluvial-type environment transported mainly by suspension and rolling and sometimes by saltation. Morphoscopy of the quartz grains revealed an abundance of sub-angular to sub-rounded grains with a shiny blunt appearance showing fractures or cracks due to shocks between the grains during transport. The sands of the department of Tiapoum therefore come mainly from distal environments and are transported by water. The environment that prevailed during the deposit of the Tiapoum department sediments is of the oxidized continental type and reworked in places.

Genetic Mechanism of Uranium Concentration in Ferruginous Sandstone of the Wajid Group in Southern Saudi Arabia

Uranium anomalies were discovered in ferruginous sandstone in the Khusayyayn Formation of the Wajid Group in southern Saudi Arabia. Based on field surveys, ground radiometric surveys, and chemical analysis, this paper summarizes the characteristics of the lithology and lithofacies of the ferruginous sandstone and analyzes the genetic mechanism of uranium concentration in ferruginous sandstone. Ferric iron basically exists in the form of Fe2O3 in ferruginous sandstone, with an average content of 28.95 wt.%. The formation period of the ferruginous sandstone occurred during the early synsedimentary and later diagenesis stages from the Carboniferous to the Devonian. The uranium anomaly is hosted in thin-bedded and lenticular ferruginous sandstone, with a uranium content ranging from 50 to 766 ppm. The average U-Ra equilibrium coefficient of ferruginous sandstone was 1.00, indicating that the uranium was weakly reformed after the uranium concentration. Ferric ions are closely related to uranium mineralization. The initial concentration of the uranium occurred during the deposition of the ferruginous sandstone. Most of the uranium was adsorbed by a ferric colloidal solution, and part of it was reduced by Fe2+, organic carbon, and sulfur in the uranium preconcentrated stage during the deposition of ferruginous sandstone. The uranium ore was superimposed, transformed, and concentrated due to the change in the pH environment in the early Neogene.

Whetstones in Roman Britain: Character, Distribution, Provenance and Industries

AbstractA substantial database of published excavation and other reports has been used to map the character and distribution in Roman Britain of whetstones, those unprepossessing implements essential in the home, farmstead, workshop and barracks for the maintenance of edge-tools and weapons. The quality of the geological identifications in the reports varies considerably, but a wide range of lithologies are reported as put to use: granite, basalts-dolerites, lava, tuff, mica-schist, slates/phyllites, Brownstones, Pennant sandstone, micaceous sandstones, grey sandstones/siltstones, Millstone Grit, Coal Measures, red sandstones, ferruginous sandstones, sarsen, Weald Clay Formation sandstones, sandy limestones, shelly limestones, cementstones, and (Lower) Carboniferous Limestone. On distributional evidence, some of these categories are aliases for alternatively and more familiarly named lithologies. Bringing ‘high-end’ products to the market, the long-running industry based on sandstones from the Weald Clay Formation (Lower Cretaceous) emerges as a British economic feature, evidenced from the Channel coast to the Scottish Borders, and with a recently demonstrated, substantial representation on the Roman near-continent. The distribution maps point to another and more complete British industry, based on the Brownstones (Old Red Sandstone, Devonian) and Pennant sandstone (Upper Carboniferous), outcropping close together in the West Country. A more systematic and geology-based treatment of excavated whetstones in the future is likely to yield yet more insights into the role these artefacts played in the economy of Roman Britain.

Diversity of benthic fauna of rhodoliths and sediments deposited on sandstone reefs in Southeast Brazil

Sandstone reefs play an important role in sheltering a great diversity of organisms. In the north sector of the state of Espírito Santo, southeastern Brazil, the beaches are characterized by ferruginous sandstone reefs in the intertidal zones. These structures have unconsolidated sediment deposited over the reefs, mainly composed of bioclastic fragments of shells and seaweed, like the rhodolith. Rhodoliths are free-living calcareous algae with three-dimensional structures. By modifying the environment's physical characteristics, they create new microhabitats capable of being inhabited by several organisms, such as meio- and macrobenthonic invertebrates. This study sought to investigate the diversity of benthic fauna (macro- and meiofauna) on different substrates (rhodoliths vs. unconsolidated sediment) in the sandstone reef and investigate whether there are differences in benthic community structure between reef zones on Gramuté Beach in the Costa das Algas Environmental Protection Area in Aracruz, Espírito Santo, Brazil. Uni and multifactor analyses showed significant differences in the composition of the benthic fauna between the substrates (p < 0.05). Meiofauna and macrofauna had higher numbers of taxa and diversity associated with rhodoliths compared to with sediments. A multivariate analysis corroborates the results of the univariate, showing variations between substrates and beach zones. The presence of rhodoliths at Gramuté Beach contributes to the heterogeneity of the ecosystem and increases the richness and diversity of the benthos. The character of the benthic community and its dynamic aspects are discussed herein and are extremely important for conservation actions.

The palynology of the Kimmeridge Clay and Carstone Formations (Upper Jurassic–Lower Cretaceous) at Middlegate Quarry, North Lincolnshire, UK, and its biostratigraphical and palaeoenvironmental significance

At Middlegate Quarry, the Carstone Formation is a c. 0.8 m thick unit of oolitic ferruginous sandstone. It rests unconformably on the lower Kimmeridge Clay Formation (KCF) and is overlain by the Hunstanton Formation (Red Chalk) with an apparently gradational junction. Marine dinoflagellate cysts (dinocysts) are present at a concentration of 9520 to 13 600 specimens per gram in the 0.15 m of KCF below the unconformity, and include taxa that confirm ammonite evidence for the intra-Lower Kimmeridgian Substage (Upper Jurassic, Cymodoce Ammonite Zone). A rich recovery of well-preserved Lower Cretaceous palynomorphs is reported for the first time from the overlying Carstone. Reworking of mudstone from the KCF into the formation appears to have provided a local argillaceous preservation matrix at Middlegate. The basal 0.15 m is dominated by palynomorphs derived from the KCF but the interval from 0.15 to 0.55 m above the unconformity mainly contains indigenous Lower Cretaceous palynomorphs. Dinoflagellate cysts are present in the Carstone at an average concentration of 454 specimens per gram, and include taxa that probably have stratigraphical range bases above the Aptian–Albian stage boundary: Cyclonephelium compactum, Cyclonephelium intonsum, Endoscrinium heikeae , Leptodinium cancellatum (consistent), Stephodinium coronatum and Stephodinium spinulosum . The additional presence of taxa with range tops/event tops in the Lower Albian Tardefurcata Ammonite Zone (common Cauca parva , frequent Canninginopsis monile and Kleithriasphaeridium eoinodes , and rare Dingodinium albertii, Discorsia nannus and Kiokansium prolatum ) indicate probable assignment to this zone. The new palynological data support previous macrofossil (brachiopod) study of the Carstone at Middlegate and nearby Melton Bottom Quarry which tentatively assigns its highest part to the Tardefurcata Zone. The palynological and palynofacies assemblages are interpreted to confirm a relatively proximal to shoreline site of deposition, possibly inner to middle neritic. Supplementary material: Quarry photographs and a palynological distribution chart are available at https://doi.org/10.6084/m9.figshare.c.5538977

Role of Hydrothermal Fluids in the Deterioration of Pictographs and Petroglyphs in Rock Shelters of The Gawilgarh Hills, Madhya Pradesh, India

India has one of the largest concentrations of rock-art sites. However, these rock shelters have deteriorated due to natural agencies. The present study was carried out in one such site in Central India, which is hosted by argillaceous and ferruginous sandstones, showing pro-minent chemical, biological and mechanical weather-ing. The results based on field investigations, petrography, XRD, FE-SEM-EDS and FTIR meas-urements have indicated that chemical weathering is caused due to infiltration of hydrothermal fluids through innumerable zones of weaknesses formed due to neotectonic activities in the Satpura Lineament Zone, especially along Gawilgarh and Salbardi Faults in this region.

Mineralogy and Geochemistry of Uraniferous Sandstones in Fault Zone, Wadi El Sahu Area, Southwestern Sinai, Egypt: Implications for Provenance, Weathering and Tectonic Setting

AbstractPaleozoic rocks in the Wadi El Sahu area are affected by many major faults in different directions. A reverse fault trending NE‐SW is exposed for about 300 m of its length as it cuts through the Abu Hamata and Adedia formations on the south side of Wadi El Sahu. A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passed through the fault plain and the surrounding fractures, forming mineralized and radioactive zone. The mineralized zone thickness ranges from 60 cm to 200 cm along the fault plain. These rocks were analyzed radiometrically using a portable gamma‐ray spectrometer, chemically by employing ICP‐ES and ICP‐MS, as well as mineralogically by both binocular and Environmental Scanning Electron microscope. Gold content was also determined by fire assay. REE and U contents reached up to 2682 and 1216 ppm, respectively. Mineralogical investigations indicated the presence of uraninite, torbernite, autunite, sklodowskite, kasolite as uranium minerals, thorite as a thorium mineral, monazite, allanite and xenotime as REE‐bearing minerals, zircon and columbite as accessory minerals, gold and nickel as precious and base metals, in addition to cassiterite, chalcopyrite, chalcocite and chrysocolla. High REE and U contents are attributed to the circulation of epigenetic U and REE‐bearing hydrothermal solutions along the fault plain and its surrounding fractures. Hydrothermal alteration processes could then be confirmed by the presence of the M‐type tetrad effect in the REE‐patterns of the ferruginous sandstone. The non‐chondritic ratio of Nb/Ta, Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad effect. The Ce and Eu anomaly with unusual REE‐patterns was represented by the presence of conjugated M‐W tetrad effects, indicating either the dual effect of hydrothermal solutions or groundwater with seawater. The results clarify that the tetrad‐effects could be used as evidence for the environment of deposition and as an indication for gold mineralization.

El Ramsa area, Southwestern Sinai, Egypt: radioactivity, mineralogy, and geochemistry studies

Um Bogma Formation represents the main target for uranium exploration at El Ramsa area. The gamma-ray spectrometric survey shows diverse measurements of radioactivity over the surveyed area, which reflects contrasting radioelement, contents for the exposed various rock types. The highest radio-spectrometric levels are located in the northeast part and scattered parts to the southwest of the study area. They are mainly associated with Um Bogma Formation. Seven uranium anomalous localities are recorded which can be used as exploration guides to explore further uranium anomalies. The highest radiometric uranium anomalies were recorded within gibbsite, carbonaceous shale, dolomite, marl, and ferruginous sandstone of Um Bogma Formation. The chemical investigations indicate enrichment in U, Cu, Mn, Cd, Ni, Zn, and Pb elements. It also reveals high uranium contents up to 640 ppm and a strong positive relation between uranium and both iron and aluminum oxides was noticed. Furthermore, high content of rare earth elements, reaching up to 5736 ppm with an average 4204 ppm, is reported in gibbsite samples. Uranium minerals such as vanuralite, sklowdowskite, and phosphuranulite were detected. The present study reveals that the source of uranium and other elements in El Ramsa area is the hydrothermal fluids which associated with the magmatic eruption during the Paleozoic events.

Integrated geophysical approach in exploration of iron ore deposits in the North-eastern Aswan-Egypt: a case study

The mines of magnetite and hematite occupy some areas of the Eastern Desert at Wadi Abu Subeira, northeast of Aswan city which is a volcanic and tectonic area. It is one of the largest arc sedimentary rock sequence affected by faulting and folding due to repeated stages of deformation. The iron deposits in this area are of oolitic type and exist in two bands inter-bedded with ferruginous sandstone and clay layers. The thickness of the bands varies from 0.5 to 3.5 m. Detailed geophysical work has been carried out on the promise site of Abu Subeira to identify the lateral and vertical distribution of the iron-ore deposits at this area. Many geophysical methods were applied in this study including Land Magnetic Survey, Electrical Resistivity Imaging (ERI), Induced Polarization (IP), and Time-Domain Electromagnetic (TDEM). Besides, rock samples from the iron ores were collected for chemical analysis. The X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques were applied for estimation of iron concentration (Fe %) and other minerals’ contents in the rock samples. The field data sets were measured along the iron ore bodies of Wadi Abu Subeira and were processed and analyzed by the proper software packages. The areas with iron ore deposits were expressed in the geophysical results by low resistivity, high chargeability, and moderate to high magnetic anomalies. Integrated interpretation of the obtained results revealed that the ore deposits exist in the form of lenses with variable thickness ranging from few meters to about 30-m thick. The mineral occurrences in Abu Subeira are managed by the major faults and the hydrothermal fluids flowing along these faults.

Understanding genesis of iron oxide concretions present in Dhandraul (Vindhyan) Sandstone: Implications in formation of Martian hematite spherules

The iron oxide concretions of Shankargarh (Allahabad), India belongs to Dhandraul Sandstone of Vindhyan Supergroup. Petrography of concretions shows abundant quartz grains embedded within the iron oxide cementation. XRD analysis of the concretion shows diagnostic peaks for quartz, hematite, and goethite. The A–CN–K and A–CNK–FM ternary diagrams drawn for concretion and host rock bulk composition clearly indicate the interaction of concretions rock with iron-bearing diagenetic fluids. A negative Ce anomaly, lower Th/U ratio, and enrichment of redox responsive trace element (e.g., vanadium) indicate concretion formation is redox-controlled. The concretions show Fe enrichment and Si depletion as compared to the host sandstone. The mass balance calculations indicate that the total Fe2O3 in the ferruginous sandstone system is 17.63 wt%. The iron mobilization and recycling in the sandstone pore spaces have formed concretions with Fe2O3 (25–35% by volume). The sandstone volume required to produce a 6 mm diameter iron oxide concretion is 1807.83 mm3. The Fe laminae and random red colouration patterns in Dhandraul sandstone are consistent with the movement of iron-enriched fluid through pores and spaces. These iron oxide concretions have similarities with the hematite spherules discovered in the Burn Formation, Meridiani Planum, Mars.

Groundwater Occurrence and Development in the Daura Area of Katsina State, Extreme Northern Nigeria

Groundwater resources of the Cretaceous Gundumi Formation and the underlying crystalline basement rocks have always been the source of water supply in Daura. Records of thirty-one boreholes drilled in the area between 1959 and 1996 were reviewed to deduce the hydrogeology of the area. The lithology of the study area obtained from strata logs and geophysical survey comprises decomposed crystalline rocks overlain by basal conglomerate, loosely cemented gravely sandstone, ferruginous sandstone and clay horizons, capped in places by laterite or silty fine sands. The area is divided into the northern and southern wellfields with average thicknesses of the Gundumi Formation of 50 m and 35 m, respectively. The average yield of the productive boreholes is 4.1 lps. The aquifer of the Gundumi Formation in the Daura area has low to moderate groundwater potential. However, the low capacities of the production boreholes are adequate to sustain the domestic water requirements of the population. Borehole site selection should be based on geophysical investigation, while the drilling rig should be capable of both rotary and downhole-hammer drilling. The borehole completion materials should be resistant to corrosion because of the low pH of the groundwater. The quality of the groundwater is generally suitable for domestic uses, though aeration or lime treatment may be necessary in some cases because of the slightly acidic nature of the groundwater.