- The paper compares four volcanic areas in Egypt - Um Safi rhyolite, El-Atshan bostonite sill, Um Domi trachyte, and Um Doweila bostonite - based on their geology, mineralization, alteration processes, and spectrometry.
- The volcanic rocks contain varying amounts of uranium and thorium as indicated by spectrometry results, with the Um Doweila bostonite having the highest uranium content on average.
- Primary minerals identified across the areas include quartz, feldspars and pyroxenes. Secondary uranium minerals including uranophane and zippeite are also present except in the Um Domi trachyte.
Geological and Geochemical Characterization of the Neoproterozoic Derudieb Me...Premier Publishers
The meta- volcano - sedimentary sequences in the northern part of the Red Sea Hills comprise a sequence of metamorphosed rocks at low green schist facies of metamorphism consisting of lava flows, tuffs to breccias and agglomerates range in composition from basalts and andesites to rhyolites. Geologically the meta volcano sedimentary sequences is divided into metavolcanic rocks and metasediments. The metavolcanic rocks range in composition from mafic to felsic. The metasediments are represented by banded schist, quartzite and marble. The samples collected for study lie within the field of sub-alkaline rocks except one mafic volcanic sample, which plot near the boundary in the alkaline field and thus follow a transitional tholeiitic to calc-alkaline trend (increasing FeO* relative to MgO). The behavior of the large ion lithophile element (LILE) in the studied metavolcanics confirms the early fractionation of plagioclase. These rocks display negative Nb anomalies, suggesting that the melt source was modified by subduction-related fluids. Tectonically all felsic samples fall in the field of volcanic arc granitoids whereas the mafic units plot firmly within the plate margin field.
Preliminary Studies of the Litho-Structural Evolution of Areas Around Obudu N...IJRESJOURNAL
ABSTRACT: Rocks underlying the northeastern sector of Obudu area forms part of the Bamenda massif which is a westward extension of the Precambrian terrains of Cameroon into southeastern Nigeria. These rocks are frequently found in the basement complex of Nigeria and include the migmatitic gneiss as the early metamorphic tectonites constituting over 60% of the outcropping rocks in the study area. The basement rock of the study area comprised of the migmatite gneiss and biotite-hornblende garnetiferous gneiss as well as the porphyroblastic gneiss and granite gneiss which formed the basement intruded by the Older granites (Pan-African granitoids). The Older granites in this area include charnockite, porphyritic granite, medium grained granite, diorite and pegmatite/aplite with relatively undeformed veins of dolerite and quartz. The presence of garnet nodules in the biotite-hornblende gneiss indicates high grade tectono-thermal metamorphism of a possible sedimentary protholith. The shearing observed in some rock outcrops are indication that there have been a series of structural deformation alongside magmatism and metamorphism in the area.
Geological and Geochemical Characterization of the Neoproterozoic Derudieb Me...Premier Publishers
The meta- volcano - sedimentary sequences in the northern part of the Red Sea Hills comprise a sequence of metamorphosed rocks at low green schist facies of metamorphism consisting of lava flows, tuffs to breccias and agglomerates range in composition from basalts and andesites to rhyolites. Geologically the meta volcano sedimentary sequences is divided into metavolcanic rocks and metasediments. The metavolcanic rocks range in composition from mafic to felsic. The metasediments are represented by banded schist, quartzite and marble. The samples collected for study lie within the field of sub-alkaline rocks except one mafic volcanic sample, which plot near the boundary in the alkaline field and thus follow a transitional tholeiitic to calc-alkaline trend (increasing FeO* relative to MgO). The behavior of the large ion lithophile element (LILE) in the studied metavolcanics confirms the early fractionation of plagioclase. These rocks display negative Nb anomalies, suggesting that the melt source was modified by subduction-related fluids. Tectonically all felsic samples fall in the field of volcanic arc granitoids whereas the mafic units plot firmly within the plate margin field.
Preliminary Studies of the Litho-Structural Evolution of Areas Around Obudu N...IJRESJOURNAL
ABSTRACT: Rocks underlying the northeastern sector of Obudu area forms part of the Bamenda massif which is a westward extension of the Precambrian terrains of Cameroon into southeastern Nigeria. These rocks are frequently found in the basement complex of Nigeria and include the migmatitic gneiss as the early metamorphic tectonites constituting over 60% of the outcropping rocks in the study area. The basement rock of the study area comprised of the migmatite gneiss and biotite-hornblende garnetiferous gneiss as well as the porphyroblastic gneiss and granite gneiss which formed the basement intruded by the Older granites (Pan-African granitoids). The Older granites in this area include charnockite, porphyritic granite, medium grained granite, diorite and pegmatite/aplite with relatively undeformed veins of dolerite and quartz. The presence of garnet nodules in the biotite-hornblende gneiss indicates high grade tectono-thermal metamorphism of a possible sedimentary protholith. The shearing observed in some rock outcrops are indication that there have been a series of structural deformation alongside magmatism and metamorphism in the area.
Exploration in Deep Weathering Profiles, Supergene, R-mode factor analysis; Multi-element association geochemistry; Assessment of Au-Zn potentiality in Gossan; Rodruin-Egypt
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Lithofacies Analysis and Petroleum Potentials of Parts of Ikom-Mamfe Embaymen...Premier Publishers
An integrated study involving detailed lithofacies analysis and source rock evaluation were carried out to reconstruct the paleoenvironment and assess the petroleum potentials of the Ikom–Mamfe embayment, southeastern Nigeria. Sedimentological field mapping involving detailed description of lithologic characteristics and facies characterisation was carried out. Geochemical studies were carried out to determine the quantity of organic matter total organic carbon (TOC), soluble organic matter (SOM), the organic matter quality (organic matter type) and level of maturity. Results show that the dominant vertical succession of the various lithofacies indicate a general finning upward succession with basal massive pebbly sandstone, medium to coarse grained sandstones with intercalation of shale and mudstones. Seven lithofacies A to G, were identified. These include: conglomerates, massive pebbly sandstone, trough cross-bedded sandstone, planar cross-bedded sandstone, shale/mudstone facies. These facies were compared with established standard facies association for determining paleoenvironment of deposition. The facies analysis carried out pointed to fluvial (alluvial – braided) depositional system as the environment of deposition. TOC values range from 0.05 – 4.13 wt% indicating poor to excellent and SOM range from 200 – 6000 ppm indicating also poor to excellent. The amount of pyrolizable carbon derived as S1 and S2 peaks suggested that the source rocks possess organic matter capable of generating hydrocarbons. Hydrogen and oxygen indices (HI and OI) ranged from 0.24 to 656 and 0.53 to 61.90 mg/gTOC respectively. Analyses of the evaluated source rock shows that the hydrocarbon potential of the study area is lean and typically of a reworked terrestrial deposit of fluvial depositional system.
Integrated ERT and Magnetic Surveys in a Mineralization Zone in Erkowit - Red...IJERA Editor
The present study focus on integrated geophysical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT imagesdefinelow resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. The study designates that correlation of magnetic and ERT anomalies with lithology are extremely useful in mineral exploration due to variations in some specific physical properties of rocks.
Geological consultant, working in a range of roles from project development/feasibility study programs and advanced exploration roles. Contracts in a variety of global locations including Egypt, Saudi Arab, and the Middle East. Commodities including Gold, base metal sulfide, Gossan/Supergene, heavy mineral sands, clay/kaolin, Silica Sand, and iron ore.
Mineral deposits known to occur in Egypt; Classification of mineral deposit in Egypt, Possible Areas for Investment in Mineral Industry in Egypt, Mineral Commodities
Uranium Occurrence in the Egypt
Types of Uranium Deposits in Egypt:
Uranium Occurrences in Pan-African Younger Granites of Egypt
Uranium Occurrences in Dykes
Uranium Occurrences in Sedimentary Rock Sequences of Egypt
Conventional- , and Nonconventional types; URANIUM RESOURCES AND RESERVES IN EGYPT
PRIMARY GEOCHEMICAL HALOES IN PROSPECTING FOR GOLD DEPOSITS, UMM RUS MINE, EASTERN DESERT, EGYPT
The estimated Au values in the Umm Rus deposit are found to be dependent, besides physico-chemical factors, on the dip angles of the housing fractures and the amount of wedging-out of the quartz veins. The highest values are anticipated in the thin-gently dipping quartz veins which are commonly detected in some parts of level-279/ and level-487/. A stepwise discriminant analysis was used to reduce a number of potential pathfinder variables to an optimum group of pathfinder variables that differentiate between mineralized and unmineralized quartz vein samples.
The estimated Au values in the Umm Rus deposit are found to be dependent, besides physico-chemical factors, on the dip angles of the housing fractures and the amount of wedging-out of the quartz veins. The highest values are anticipated in the thin-gently dipping quartz vein
GOLD CONTENTS IN RELATION TO GEOMETRIC
FEATURES OF QUARTZ VEINS
Exploration in Deep Weathering Profiles, Supergene, R-mode factor analysis; Multi-element association geochemistry; Assessment of Au-Zn potentiality in Gossan; Rodruin-Egypt
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Lithofacies Analysis and Petroleum Potentials of Parts of Ikom-Mamfe Embaymen...Premier Publishers
An integrated study involving detailed lithofacies analysis and source rock evaluation were carried out to reconstruct the paleoenvironment and assess the petroleum potentials of the Ikom–Mamfe embayment, southeastern Nigeria. Sedimentological field mapping involving detailed description of lithologic characteristics and facies characterisation was carried out. Geochemical studies were carried out to determine the quantity of organic matter total organic carbon (TOC), soluble organic matter (SOM), the organic matter quality (organic matter type) and level of maturity. Results show that the dominant vertical succession of the various lithofacies indicate a general finning upward succession with basal massive pebbly sandstone, medium to coarse grained sandstones with intercalation of shale and mudstones. Seven lithofacies A to G, were identified. These include: conglomerates, massive pebbly sandstone, trough cross-bedded sandstone, planar cross-bedded sandstone, shale/mudstone facies. These facies were compared with established standard facies association for determining paleoenvironment of deposition. The facies analysis carried out pointed to fluvial (alluvial – braided) depositional system as the environment of deposition. TOC values range from 0.05 – 4.13 wt% indicating poor to excellent and SOM range from 200 – 6000 ppm indicating also poor to excellent. The amount of pyrolizable carbon derived as S1 and S2 peaks suggested that the source rocks possess organic matter capable of generating hydrocarbons. Hydrogen and oxygen indices (HI and OI) ranged from 0.24 to 656 and 0.53 to 61.90 mg/gTOC respectively. Analyses of the evaluated source rock shows that the hydrocarbon potential of the study area is lean and typically of a reworked terrestrial deposit of fluvial depositional system.
Integrated ERT and Magnetic Surveys in a Mineralization Zone in Erkowit - Red...IJERA Editor
The present study focus on integrated geophysical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT imagesdefinelow resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. The study designates that correlation of magnetic and ERT anomalies with lithology are extremely useful in mineral exploration due to variations in some specific physical properties of rocks.
Geological consultant, working in a range of roles from project development/feasibility study programs and advanced exploration roles. Contracts in a variety of global locations including Egypt, Saudi Arab, and the Middle East. Commodities including Gold, base metal sulfide, Gossan/Supergene, heavy mineral sands, clay/kaolin, Silica Sand, and iron ore.
Mineral deposits known to occur in Egypt; Classification of mineral deposit in Egypt, Possible Areas for Investment in Mineral Industry in Egypt, Mineral Commodities
Uranium Occurrence in the Egypt
Types of Uranium Deposits in Egypt:
Uranium Occurrences in Pan-African Younger Granites of Egypt
Uranium Occurrences in Dykes
Uranium Occurrences in Sedimentary Rock Sequences of Egypt
Conventional- , and Nonconventional types; URANIUM RESOURCES AND RESERVES IN EGYPT
PRIMARY GEOCHEMICAL HALOES IN PROSPECTING FOR GOLD DEPOSITS, UMM RUS MINE, EASTERN DESERT, EGYPT
The estimated Au values in the Umm Rus deposit are found to be dependent, besides physico-chemical factors, on the dip angles of the housing fractures and the amount of wedging-out of the quartz veins. The highest values are anticipated in the thin-gently dipping quartz veins which are commonly detected in some parts of level-279/ and level-487/. A stepwise discriminant analysis was used to reduce a number of potential pathfinder variables to an optimum group of pathfinder variables that differentiate between mineralized and unmineralized quartz vein samples.
The estimated Au values in the Umm Rus deposit are found to be dependent, besides physico-chemical factors, on the dip angles of the housing fractures and the amount of wedging-out of the quartz veins. The highest values are anticipated in the thin-gently dipping quartz vein
GOLD CONTENTS IN RELATION TO GEOMETRIC
FEATURES OF QUARTZ VEINS
The Wadi Sikait Complex:
A Fertile- Post-Collisionl Granite-Pegmatite Suite, Eastern Desert, Egypt.
The Pan-African, Wadi Sikait Complex (WSC), in the south Eastern Desert of Egypt, is a late-tectonic, subsolvus strongly peraluminous, S-type, post-collisionl granite in the Sikait area that features an unambiguous genetic linkage with a proximal, zoned cluster of Be-, REE- and Nb-Ta bearing pegmatites (Abu Rusheid and Nugrus-Sikait area). The WSC is an arcuate belt of orthogneisses, migmatites and other high-grade metamorphic rocks, which mark the boundary between the central Eastern and the south Eastern Deserts of Egypt. The WSC consists of seven internal units (WSC-1 to -3 and PL-1 to -4) that range from chemically primitive biotite, garnet and sillimanite granites (WSC-1 and –2) to a highly evolved, tourmaline- and muscovite- bearing pegmatite granite facies (PL-1 to –4) locally containing endogenous emerald/beryl, molybdinite and cassiterite. Salient petrochemical attributes include A/CNK molar which varies from 1.15 to 1.75, a wide range of SiO2 (68.7-76.9%), high Al2O3 (14.1-16.0%), low CaO (<2.35%) and FeOt+MgO+TiO2 (0.36-6.62%), and with increasing fractionation, enrichment of Na2O, K2O, B, F, Be, Rb, Ga and Li, and depletion of Ba, Sr, Zr, REE and LREE. Strong fractionation is also revealed by Al/Ga (1370-6789), Ba/Rb (<0.01-12), Ca/Sr (21-201), K/Ba (19-9545), Mg/Li (4.26-1421), Na2O/K2O (0.21-34), (Ce/Yb)CN (0.89-83.25), and Eu/Eu* (<0.05-2.29). REE distribution patterns of rare-element pegmatites are lower in REE contents and flatter with prominent negative Eu anomaly than those of the related granites. The REE concentration and the (Ce/Yb)CN ratio decrease from the WSC-1 and -2 through PL-1 and -2 (fine-grained leucogranite) and PL-3 (pegmatitic leucogranite) to the PL-4 (potassic pegmatites).
Genesis of the strongly peraluminous, S-type granite and the associated rare-element pegmatite in the Sikait-Nugrus area is explained by a complex interplay of petrogenetic processes. Rare-elements and boron were previously concentrated in (wackes and mudstone) pelitic sediments deposited in large basins. These rocks underwent step-wise rock dehydration reactions involving muscovite and biotite, under fluid-absent conditions, and successively released these elements to anatectic melt. Rare-elements and volatiles were progressively concentrated via crystal-melt fractionation, the Harker trends of which were obscured by two stages of extraction of residual melt and by episodic, subsolidus redistribution via base-cation leaching. The late magmatic history of the WSC is marked by widespread exsolution of a volatile-rich phase, dispersion of a rare-element- F-B-Be-rich fluid along shear zones and ensuing emigration of rare-element-rich melt-fluid systems upward from the cupola, which led to the regionally zoned Sikait-Nugrus area
Myanmar known until recently as Burma, is slowly but steadily starting to attract foreign investment, driven mainly by international resource firms eager to tap into the mineral-rich South East Asia's country. After more than half a century of military ruling, Burma has started benefitting from the recent suspension of sanctions by Canada, the United States and the European Union. Myanmar's gold production is increasing and could prove a key factor for the country's economic growth, but many gold miners are suffering from lung diseases due to inadequate equipment and antiquated practices. In mineral-rich areas of Kachin State, taxes from Burmese and Chinese gold mining provides an important income stream to the Kachin Independence Organization. However, these mining companies use mercury in an environmentally hazardous extraction process, which can lead to long-lasting damage for the area's forests and river ways.
Tectonic Processes and Metallogeny along the Tethyan Mountain Ranges of the M...MYO AUNG Myanmar
https://www.researchgate.net/publication/309130798_Tectonic_Processes_and_Metallogeny_along_the_Tethyan_Mountain_Ranges_of_the_Middle_East_and_South_Asia_Oman_Himalaya_Karakoram_Tibet_Myanmar_Thailand_Malaysia
The genesis of mineral deposits has been widely linked to speci c tectonic settings, but has less frequently been linked to tectonic processes. Understanding processes of oceanic and continental collision tectonics is crucial to understanding key factors leading to the genesis of magmatic-, metamorphic-, hydrothermal-, and sedimentary-related mineral deposits. Geologic studies of most ore deposits typically focus on the nal stages of concentration and emplacement. The ultimate source (mantle, lower crust, upper crust) of mineral deposits in many cases remains more cryptic. Uniquely, along the Tethyan collision zones of Asia, every stage of the conver- gence process can be studied from the initial oceanic settings where ophiolite complexes were formed, through subduction zone and island-arc settings with ultrahigh- to high-pressure metamorphism, to the continental col- lision settings of the Himalaya, and advanced, long-lived collisional settings such as Afghanistan, the Karakoram Ranges, and the Tibetan plateau. The India-Asia collision closed the intervening Neotethys ocean at ~50 Ma and resulted in the formation of the Himalayan mountain ranges, and increased crustal thickening, metamor- phism, deformation, and uplift of the Karakoram-Hindu Kush ranges, Tibetan plateau, and older collision zones across central Asia. Metallogenesis in oceanic crust (hydrothermal Cu-Au; Fe, Mn nodules) and mantle (Cr, Ni, Pt) can be deduced from ophiolite complexes preserved around the Arabia/India-Asia collision (Oman, Ladakh, South Tibet, Myanmar, Andaman Islands). Tectonic-metallogenic processes in island arcs and ancient subduc- tion complexes (VMS Cu-Zn-Pb) can be deduced from studies in the Dras-Kohistan arc (Pakistan) and the various arc complexes along the Myanmar-Andaman segment of the collision zone. Metallogenesis of Andean- type margins (Cu-Au-Mo porphyry; epithermal Au-Ag) can be seen along the Jurassic-Eocene Transhimalayan ranges of Pakistan, Ladakh, South Tibet, and Myanmar. Large porphyry Cu deposits in Tibet are related to both precollisional calc-alkaline granites and postcollisional alkaline adakite-like intrusions. Metallogenesis of continent-continent collision zones is prominent along the Myanmar-Thailand-Malaysia Sn-W granite belts, but less common along the Himalaya. The Mogok metamorphic belt of Myanmar is known for its gemstones associated with regional high-temperature metamorphism (ruby, spinel, sapphire, etc). In Myanmar it is likely that extensive alkaline magmatism has contributed extra heat during the formation of high-temperature meta- morphism. This paper attempts to link metallogeny of the Himalaya-Karakoram-Tibet and Myanmar collision zone to tectonic processes derived from multidisciplinary geologic studies.
Grossular bearing jadeite omphacite rock in the myanmar jadeite areaYMCA Mandalay
The Myanmar jadeitite deposits near Hpakant have attracted remarkable attention of geologists and gemologists not only for being the largest jadeite jade deposit in the world, producing high quality jade with the glassy imperial green for more then 300 years.
Geoengineering Characterization of the Rock Masses of Northern Face of Jabal ...IJERA Editor
This paper is aimed at the description and the geotechnical characterization of the Tertiary granitic rock masses of the northern face of Sabir Mountain, Taiz city, Yemen, for the first time. For accomplishing this task, direct and indirect approaches are adopted. The direct approach is represented by field and laboratory investigations. Field investigations include discontinuity (joints) measurements/evaluation, applied Rock Mass Rating (RMR) system and Geological Strength Index (GSI) system, in addition to field tests, while laboratory investigations encompass physico-mechanical tests carried out on granitic rock materials. Indirect approach for the estimation of shear strength parameters (c, φ), compressive strength (σcm), tensile strength (σtm) and deformation modulus (Erm) of these rock masses was made by applying the generalized Hoek–Brown failure criterion using geotechnical Roc-Lab software. The laboratory results indicate that the Tertiary granitic rock masses show wide range of variations in their physico-mechanical characteristics owing to degree of weathering /alteration and microfractures. The intact samples of Sabir granitic (Tg) rocks show “Moderate” to “High” density, “Low” to "Medium" porosity, “Good" to "Marginal” water absorption capacity and “Weak” to “Very Strong” strength. Stereographically, three main sets of discontinuities (joints) are identified at each station; however, the fourth joint set occurs, in addition to random joint sets. The discontinuities (joints) trend predominately in NE-SW and NW-SE directions in conformity with the regional structures or faults. According to Jv j/m³ values, the degree of jointing of these rock masses are varied from “Moderate” to “High” jointing. These rocks are categorized as “Fair” to “Excellent” quality, “Fair” to “Good/Very Good” quality and “Poor” to “Very Good” quality classes according to RQD, RMR89 and GSI respectively. Values of the shear strength parameters (c and φ) and the other rock mass parameters (σtm, σc , σcm and Erm) show variations depending on the rock mass quality and properties of intact rock. However, in general the values of the rock mass parameters are found to increase with increase in the quality of rock mass and intact rock properties.
Base Metal Mineralization in the Precambrian Rocks of Okemesi-Ijero Area, So...Scientific Review SR
The evaluation of base metals in the bedrocks of Okemesi / Ijero area, southwestern Nigeria has
been carried out to assess their potentials, level of accumulation and enrichment. The methodology included
systematic geological and geochemical mapping of the rocks using grid-controlled sampling method at a
sampling density of one sample per 500m. Ten rock samples were collected at different locations of the study
area. The results obtained showed that the major oxides such as SiO
2, Al2O3, TiO
2,
Fe
2O3, MnO, MgO, CaO,
Na2O, K2
O and P2O5 were detected in variable proportions. While SiO2 varied between 70.59% and 98.70%,
Al2O3 ranged between 15.73% and 0.61%. There is abundance of barium (Ba), silver (Ag) and gold (Au) with
concentration values of 1.6-9.8, 1.24-7.1 and 0.05-10.00 ppm respectively. Base metals such as Cu, Zn, Pb, Bi
and Cr enrichment factors and their geo-accumulation index indicates moderately significance to very high
enrichment of Cu (10 – 70%) , Pb (20 – 40%) and Bi (10 – 40%). The geo-accumulation indices suggest
geogenic concentration of the base metals in the host rocks rather than anthropogenic inputs. The PCA elements
loaded Au, As, Ag, Pt and Os on the same factor and they are pathfinder elements of Gold. Correlation
coefficients indicate strong positive correlations between the elements. This implies that they are strongly related
and therefore of the same source, also suggesting geogenic sources.
Similar to Comparative Study Between Some Uraniferous Volcanic Rocks, Eastern Desert, Egypt (20)
Base Metal Mineralization in the Precambrian Rocks of Okemesi-Ijero Area, So...
Comparative Study Between Some Uraniferous Volcanic Rocks, Eastern Desert, Egypt
1. COMPARATIVE STUDY BETWEEN SOME URANIFEROUS
VOLCANIC ROCKS, EASTERN DESERT, EGYPT
By
I. H. Ibrahim and M. E. Ibrahim
Nuclear Materials Authority, P.O. Box: 530 El Maadi, Cairo, Egypt.
Corresponding author: ibrahim170@yahoo.com
ABSTRACT
Four volcanic areas; Um Safi rhyolite (USR) and El-Atshan bostonite sill (EBS) at the Central
Eastern Desert, whereas, Um Domi trachyte (UDT) and Um Doweila bostonite (UDB) at the
South Eastern Desert of Egypt were choosen for comparison on the bases of geologic setting,
mineralogy, geochemistry and spectrometric investigations.
UDT and UDB are alkaline to per-alkaline in nature while USR and EBS are metaluminous to
slightly peraluminous regime. USR, EBS and UDT are affected by diagenetic processes
whereas hydrothermal processe is common in UDB.
The base metals (pyrite, cassiterite, arsenopyrite, corondite, wolframite and chrysocolla) are
common in USR, UDB, EBS and UDT in decreasing order. The secondary uranium minerals
(uranophane, zippeite and kasolite) are common in all volcanic areas except UDT.
Spectrometric results indicate that the eU/eTh ratios decreases (0.6-0.3) from EBS and UDB
through USR to UDT.
Keywords: Rhyolite, Bostonite, Trachyte, Diagenetic processes.
The paper = 15 ages, 6 figures, 4 tables, 29 references
2. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
57
INTRODUCTION
Volcanic activity in Egypt spanned a long period and marked a change in tectonic setting from
ocean floor and subduction related volcanics in the Precambrian to intraplate volcanicity in the
Phanerozoic. During the Phanerozoic continental intraplate volcanic activity in Egypt was
intermittent and resulted in extrusion of volcanic rocks of wide compositional variation size and
mode of eruption. Geochronological studies on these Phanerozoic volcanics (El-Shazly, 1977,
Hashad et al., 1978, Ressetar et al., 1981, Stairs et al., 1991) revealed three phases of activity in
Egypt. These are, Paleozoic (233-395 Ma), Mesozoic (74-191 Ma) and Tertiary (15-48 Ma).The
dykes and plugs are part of the tectono-magmatic events that had affected the Eastern Desert of
Egypt during the Mesozoic.
The aim of our contributions is to comparison on the bases of geologic setting, mineralization,
alteration processes and spectrometry of four volcanic areas include; Um Safi rhyolite (USR),
El-Atshan bostonite sill (EBS), Um Domi trachyte (UMT) and Um Doweila bostonite (UDB)
(Fig. 1).
Figure 1
3. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
58
METHODOLOGY
The idenified minerals has been carried out by means of binocular microscope, XRD (Model
PW 1830) and examined by the environmental scanning electron microscope (ESEM) supported
by qualitative energy dispersive spectrometer (EDS) unit at the Nuclear materials Authority of
Egypt. The gamma ray spectrometry measurements were carried out using a GS-256
spectrometer with a 7.62x7.62 cm2
sodium iodide (Thalium) [Na1(Ti)] crystal detector. Major
elements for 69 samples were analyzed by wet chemical in the Nuclear materials Authority
(NMA), Egypt. Precision of the analytical data was monitored by international rock standards
and is better than 3% for major elements.
GEOLOGIC SETTING
Um Safi rhyolite (USR) was mapped previously as felsite by Akaad and El-Ramly (1963); El-
Ghawaby (1966); Akaad et al. (1996) and Abdalla (2001). USR extruded the volcano-
sedimentary associations (slate, phyllite, Banded Iron Formation and schist), serpentinites and
ortho-amphibolites with Knife sharp contact, forming small oblated body striking NW-SE,
covering about 0.3 km2
(Fig. 2). The bulk compositions is mainly rhyolite showing banded and
flow structures, which may appear as coloured bands strips or lines of spherulites and
spherulitic textures.
Pyroclastics are represented by breccias, tuffs and welded tuffs and composed mainly of crystals
and rock fragments in fine-grained groundmass. USR show different degrees of alteration,
hematitization, kaolinitization and silicification. They are invaded by N-S sub-vertically
greisenized microgranite, which shows exfoliated and cavernous. The pyroclastics and greisen
rocks gain importance due to their high intensities of radioactivity. Visible non-radioactive
minerals are observed such as pyrite, arsenopyrite and manganese dendrites, as well as, violet
fluorite and metallic black veinlets (N-S trend).
El-Atshan bostonite sill (EBS) have been studies by El-Ghawaby (1973), Assaf (1973) and El-
Shazly (1977). Most workers considered the Hammamat sediments in El-Atshan as post-
orogenic deposits accumulated in disconnected intermountain basins. The rocks of El-Atshan
area can be classified into metasediments (metamudstones, chlorite schists and muscovite
schists), Hammamat sediments (siltstones, sandstones and conglomerates), bostonite sill and
quartz veins (Fig. 3).
EBS extends for about 660 m with a thickness ranging between 3 to 30m with general strike of
N30˚E and moderately dipping (25-40˚) to NW. They cut by some faults in various direction but
the most predominant are striking in the NW-SE and NE-SW directions. EBS is buff in colour,
highly jointed, fine- to medium-grained, knife peaks with high resistant and the weathered parts
are pale cream yellow with pitted surface. Two disturbed points along the EBS (shaft-1 and
shaft-2 from one side and cliff on the northern part from the other side) are characterized by a
lot of occurrences of uranium mineralization.
Um Domi trachyte (UDT) and Um Doweila Bostonite (UDB) are essentially limited to work
by El-Manharawy (1972); Hashad and Mahfouz, (1976); Hashad et al., (1981); Akaad (1996);
Kamel et al. (1985); Ibrahim et al. (2002); Heikal (2003); Saleh et al. (2004). They crops out in
the southeastern Desert of Egypt.
4. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
59
UDT is semi-rounded in shape (0.5 Km2
) and elevate 364 m above sea level (Fig. 4). It is
located between two conjugate wrench faults (right-hand) trending N-S and NW-SE. The area is
dissected by strike-slip faults (NE-SW, NW-SE and N-S) with obvious displacement along the
main Wadis. UDT is hard, fractured, fine- to medium-grained and highly sheared at their
contact with volcanogenic sediments. The grain size decreases toward the western side of the
trachyte plug. Visible sulphide is common by naked eye. Hematitization, kaolinitization and
albitization are the alteration processes. The volcanogenic sedimentary sequence can be divided
into lower unit, consisting mainly of clast and matrix supported conglomerates, being
interbedded by minor bedded greywacke and chlorite-epidote schist. The upper unite is
composed mainly of grey to greenish slates and interbedded with thin beds of mudstone.
5. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
60
UDB extends in the NE-SW direction for about 14 km with 1-10 m width crosscutting three
country rocks; volcanogenic meta-sediments, meta-andesite and marble with sharp contacts
(Fig. 5). The northeastern and southwestern parts of the UDB (8 Km long) are characterized by
fine- to medium-grained, equigranular, whereas the middle part of UDB (3 km long) is
characterized by porphyritic texture and low intensity of radioactivity compared with the other
parts. Silicification ferrugination, fluoritization and kaolinization processes are predominating
features due to hydrothermal solutions.
The fracture framework of Um Doweila area is characterized by two semi-perpendicular
dominant trends (NE-SW and NW-SE) resulting from an extensional phase of deformation
perior in age to the emplacement of bostonite within the NE-SW main fracture trend. These two
main fracture trends are associated with two minor NNW-SSE to N-S and ENE-WSW to E-W
trends. In fact, these fracture systems are recorded cutting among the country rocks
(volcanogenic metasediments, meta-andesite and marble), whereas the Nubian sandstones are
deposited later these trends.
Table 1: Comparison in geologic setting between the four volcanic areas.
USR EBS UDT UDB
Location Central Eastern Desert Southern Eastern Desert
Country
Rocks
Volcano-
sedimentary
associations +
serpentine + ortho-
amphibolite
Metasediments Volcanogenic
sediments
Volcanogenic
meta-sediments
+ meta-andesite
+ marble
Area 0.3 km2
Extends 660 m
with 3 to 30 m
width
0.5 Km2
Extends 14 km
with 1-10 m
width
Shape
Oblated body
striking NW-SE
Sill
Semi-rounded in
shape
Dyke
Essential
minerals
Quartz + sanidine
+ secondary
muscovite
Sodic feldspar
+ orthoclase +
quartz.
Quartz +
plagioclase + alkali
amphiboles +
alkali feldspars +
alkali pyroxene
Quartz +
microperthite +
riebeckite +
rare
arfvedsonite
Accessories
Zircon + apatite
fluorite+ pyrite +
opaques
Zircon +
pyrite +
apatite +
fluorite +
opaques
Zircon+ apatite+
fluorite+ pyrite +
opaques
Zircon +
apatite +
fluorite +
opaques
Tectonics Extend in NW-SE
direction
Extend in
N30˚E
direction
Extend in NNW-
SSE direction
Extend in NE-
SW direction
USR= Um Safi Rhyolite UDT= Um Domi Trchyte
EBS= El-Atshan Bostonite Sill UDB= Um Doweila Bostonite
DISTRIBUTION of eU and eTh
The eU-content in fresh USR ranges from 17 to 34 ppm with an average 26 ppm, and the
eTh-content ranges from 32 to 75 ppm with an average 50 ppm, while the average eTh/eU ratio
6. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
61
is equal 1.9 (Table 2). The eU and eTh values of USR are indicate to uranium enrichment rather
than thorium. The field radiometric measurements localized three radioactive anomalies, two
within pyroclastics and one within greisenized microgranite.
Table 2: Average of eU (ppm), eTh (ppm), K (%), eU/eTh and eTh/eU ratios of the four
volcanic rocks.
Rock types Radiometric measurements
eU (ppm) eTh (ppm) K(%) eU/eTh eTh/eU
USR
(n=86)
min. 17 32 1.75 0.4 1.7
max. 34 75 4.29 0.6 2.2
average 26 50 2.99 0.5 1.9
EBS
(n=204)
min. 2 4 1.20 0.1 0.4
max. 115 70 8.10 2.7 15
average 10 18 3.34 0.6 2.6
UDT
(n=94)
min. 6 23 2.90 0.10 2.2
max. 37 112 7.10 0.45 9.7
average 23 77 5.31 0.3 3.6
UDB
(n=123)
min. 3 5 0.20 0.1 0.2
max. 570 245 6.60 5.5 20
average 50 77 2.58 0.6 2.7
n= Number of analyzed samples
USR= Um Safi Rhyolite. EBS= El-Atshan Bostonite Sill.
UDT= Um Domi Trchyte. UDB= Um Doweila Bostonite dyke.
8. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
63
Results of the gamma-ray spectrometric survey of the EBS show the eU-content ranges from 2 to
115 ppm with an average 10 ppm, and the eTh-content ranges from 4 to 70 ppm with an average
18 ppm, while the eTh/eU ratio is equal 2.61 (Table 2). The eU and eTh values of EBS are
indicate to uranium slightly enrichment rather than thorium. The high eU-contents are restricted
mainly in site shaft No-1 and shaft No-2.
Detailed spectrometric studies of UDT show the eU-content ranges from 6 to 37 ppm with an
average 23 ppm, and the eTh-content ranges from 23 to 112 ppm with an average 77 ppm,
while the average eTh/eU ratio is equal 3.9 (Table 2).
Detailed spectrometric studies were carried out along NW-SE profiles at a grid pattern of
10x10m for UDB. Generally the eU-content along UDB ranges from 3 to 570 ppm with an
average 50 ppm, and the eTh-content ranges from 5 to 245 ppm with an average 77 ppm, while
the average eTh/eU ratio is equal 2.7 (Table 2).
MINEROLOGY
The volcanic rocks of USR seem to host uranium are more than sub-alkaline and calc-alkaline
varieties (Leroy and Aniel, 1991). Columbite, uranothorite and zircon minerals were recorded as
fracture filling in the sheared parts of this felsite rocks (El-Ghawaby, 1966). The uranium
occurrence of El-Atshan was subjected to geologic and exploratory works since its discovery in
1962 by Nuclear Materials Authority. Primary mineral (Atshanite), secondary minerals
(uranophane, bequerelite, schoepite, kasolite, soddyite and zippeite) and manganese iron
minerals (psilomelane, pyrolusite, titanomagnetite, pyrite, hematite, goethite and limonite) have
been identified by Abd el Gawad (1964). The mineralogical studies of UDT (Saleh et al., 2004)
revealed the presence of rare earth silicates, tantalite, ilmenorutile, chrysocalla, zircon and
fayalite minerals. The mineralogical study of the UDB (Ibrahim et al., 2005) reveal the
presence of uranophane, beta-uranophane, wolframite (hueberite) monazite, zircon, rutile and
opaques whereas, pyrite is a common in volcanogenic metasediments.
9. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
64
Table 3: Minerals identification in the four volcanic rocks.
USR EBS UDT UDB
Primary U-
minerals
-
Atshanite
- -
Secondary
U-minerals
Kasolite
Uranophane +
Kasolite +
- Uranophane +
β-uranophane
Uranium
bearing-
minerals
Yttrialite +
Betafite +
Plumbobetafite
-
Rare earth
silicates
Thorium
minerals
Uranothorite - - -
Tantalum and
Niobium
metals
Columbite -
Tantalite +
Ilmenorutile
-
Base metal
minerals
Pyrite +
Cassiterite +
Arsenopyrite +
Coronadite
Pyrite Chrysocolla Pyrite +
Wolframite
Manganese +
iron minerals
Pyrolusite +
Hematite +
Goethite +
Limonite
Psilomelane +
Pyrolusite +
Titanomagnetite
+ Hematite +
Goethite +
Limonite
Fayalite -
Accessories
Allanite +
Fluorite +
Zircon
Zircon Zircon
Monazite +
Zircon + Rutile
USR= Um Safi Rhyolite. UDT= Um Domi Trachyte.
EBS= El-Atshan Bostonite Sill. UDB= Um Doweila Bostonite.
RESULTS OF CHEMICAL ANALYSES
Average of major chemical composition for 69 samples are listed in Table 4. The alteration box
plot is used to discriminate between geochemical trends of diagenetic alteration from those
hydrothermal one. This index (Ishikawa alteration index: [100 (MgO + K2O) / (MgO + K2O +
CaO + Na2O)] relates to the replacement of plagioclase by sericite and chlorite during
hydrothermal alteration(Ishikawa et al., 1976; large et al., 2001). The index is superior to using
Na2O alone because of its ability to distinguish alkali depletion related to hydrothermal
alteration. The chlorite-carbonate-pyrite index [100 (FeO + MgO ) / (FeO + MgO + K2O +
Na2O)] measures the degree of chlorite, (Fe, Mg) carbonate, and or pyrite alteration.
The geochemical data for USR, UDT and EBS are illustrated in an alteration box of diagenetic
trend. USR and UDT lies in trend No.9, indicate the common digenetic minerals albite, K-
feldspar early digenetic trend of K-feldspar replacing albite and least altered box (Gifkins and
Allen, 2001) (K-metasomatized and albitization alteration). The average EBS samples lies in
10. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
65
trend No. 7. indicatethe common diagenetic minerals (albite & chlorite) are typical of seawater
interaction at low temperature. The reactions that describe these alteration processes include:
The first reaction is typical of sericite replacement of albite in volcanic rocks in the outer parts
of the alteration system (Date et al., 1979 and Eastoe et al., 1987). The second reaction is
important close to massive sulphide mineralization where chlorite rich assemblages become
dominant over sericite rich assemblages (Lentz, 1999, Schardt et al., 2001). The average UDB
data is plotted in common proximal hydrothermal minerals; sericite, chlorite, pyrite, dolomite
and ankerite which lies on the right hand CCPI axis and the upper AI axis (Fig. 6). The samples
are plotted between in trends 3, 4 and 5 which represented by chlorite + sericite + pyrite and
carbonate.
SUMMARY AND CONCLUSIONS
A- In USR, the average of eTh/eU ratios are increased from greisenized microgranite
through fresh rhyolite to pyroclastic samples (kaolinized and argillite). The lowering of the
eTh/eU ratio indicates redistribution and localization of secondary uranium mineral
(kasolite). The enrichment of U and Th in pyroclastics may indicate the stabilization of them
in late- to post-magmatic fluids. In the pyroclastics samples. Kaolinitization, ferrugenation,
and argillation represent the hydrothermal alteration processes. The widespread sericitization
through the rhyolite rocks provides additional evidence of large-scale movement of solutions
through these rocks. The hexavalent U is ready leached from rhyolites by dilute acid
solutions so some U may have been transported as UO2(OH)+
and UO2
-
complex.
UM Safi Rhyolite pyroclastics appears to have provided less-welded layers and lenses. This
is coincidence with the similar observation (Smellie, 1982) described from Duobblon
rhyolitic ignimbrites. The leached U from solutions percolating through fractures, fissures
and permeable bands were re-deposited and sink. The pyroclastics were erupted with
explosive violence as a turbulent mixture of hot, expanding gases and gas-emitting lava
fragments at relatively low pressures. The base metal minerals (pyrite, arsenopyrite and
corondite) are formed in the deeper part in the epithermal zone. In the next zone to the top
where ascending solutions rise further towards the surface and mingled with the descending
meteoric water, precipitation of secondary uranium mineral (kasolite) and U-bearing
minerals (plumbobetafite, columbite, yttrialite, betafite and uranothorite) occur as a function
of oxidation and failing temperature.
11. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
66
Table 4: Average of major chemical composition of the four volcanic rocks.
Major Oxides USR
n= 11
EBS
n= 20
UDT
n= 17
UDB
n= 21
SiO2
Min.
Max.
Average
57.44
65.94
61.91
59.60
69.00
64.27
69.49
81.50
72.73
42.20
72.20
59.85
TiO2
Min.
Max.
Average
0.17
0.69
0.32
0.10
1.91
0.51
0.10
0.13
0.12
0.15
1.51
0.52
Al2O3
Min.
Max.
Average
12.66
15.69
14.58
11.50
15.98
13.73
8.94
14.62
12.41
7.40
18.40
11.14
Fe2O3
Min.
Max.
Average
2.77
7.17
5.35
2.19
7.10
4.23
0.81
4.39
2.41
6.00
11.5
9.58
FeO
Min.
Max.
Average
0.2
0.66
0.41
1.00
3.20
1.92
0.20
0.76
0.46
2.18
4.10
3.01
MnO
Min.
Max.
Average
0.08
0.26
0.15
0.03
0.22
0.13
0.06
0.18
0.10
0.04
0.23
0.17
MgO
Min.
Max.
Average
0.08
1.60
0.91
0.80
3.96
1.61
0.80
2.80
1.24
1.16
7.26
2.36
CaO
Min.
Max.
Average
0.84
3.92
1.72
0.68
2.24
1.52
1.12
2.80
1.80
0.39
8.70
2.39
Na2O
Min.
Max.
Average
0.21
6.61
5.99
4.00
7.62
5.92
0.34
4.63
3.08
0.41
6.10
1.79
K2O
Min.
Max.
Average
2.61
3.48
2.87
2.08
5.40
4.22
0.83
4.55
2.72
0.47
4.40
3.09
P2O5
Min.
Max.
Average
0.01
4.54
2.95
0.01
1.00
0.28
0.07
0.13
0.09
0.05
1.11
0.86
n= Number of analyzed samples
USR= Um Safi Rhyolite. UDT= Um Domi Trachyte.
EBS= El-Atshan Bostonite Sill. UDB= Um Doweila Bostonite dyke.
B- EBS was extruded into the tilted strata of the metasediments parallel to the foliation planes.
During the cooling of the bostonite sill, shrinkage and cracking took place parallel to the
foliation planes giving rise to the formation of the major NE-SW set of fractures especially
at the contact with the host rocks. Upon the final cooling and consolidation sill the shrinkage
and cracking process is continued leaving the bostonite with radial group of joint. Later on,
the fractures of this trend has been reopened and refilled with quartz during a NW-SE
12. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
67
trending extensional phase of deformation. Moreover, the NE-SW fracture set is recorded as
major new formed normal faults along W. El Atshan parallel to the bostonite sill indicating
an other NW-SE trending extensional phase of deformation.
13. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
68
It could be concluded that the major NE-SW trending fracture sets were acted as the
principal channel ways for the mineralized solution while the re-deposition took place within
almost all the minor fracture trends with no preferred orientation. This could suggest
meteoric water origin for the mineralized solution rather than the hydrothermal origin. This
conclusion is in agreement with the results obtained from the geochemical analyses
(digenesis effect).
El-Atshan bostonite sill is considered to be low grade uranium mineralization that related to
alkaline volcanic rocks. This area seems to have been affected by many groundwater
activities. The area is also characterized by the absence of post magmatic activities
(chemical traps for U mineralization).
The U mineralization is restricted only to local spots concentrated at the small alteration
parts of the metamorphic belt in close contact with the bostonite sill. Although the visible
uranium mineralization in both the metamorphic belts and Hammamat sediments is absent,
their eU/eTh ratio (>1) confirm the mobilization idea of the U towards the bostonite sill.
C- UDT occurs as semi-rounded (0.5 Km2
) form of highly sheared at their contact with
volcanogenic sediments and located between two conjugate wrench faults trending N-S and
NW-SE and parallel to the extensional direction (NNW-SSE). Geochemically, the UDT plug
has an alkaline affinity and silica-oversaturated and may be attributed to extensive alkali
feldspar fractionation. It is affected by both K- and Na-metasomatism related to diagenetic
process.
The accessories of UDT plug are composed of tantalite, REE silicate, chrysocolla,
ilmenorutile, zircon, apatite and pyrite. Although the nature and distribution of such
minerals are controlled by magma features, they may be significantly affected by diagenetic
process.
The absences of post-magmatic activity (i.e. chemical trap for uranium) and any significant
shear zones in UDT incorporated with the low uranium content (37 ppm). Finally, UDT plug
could be considered as a good target for exploration on tantalite and REEs silicate.
D- UDB could be considered the longest U-bearing dyke in the Eastern Desert of Egypt. It
extends in the NE-SW direction for about 11 km and ranges from 1-10 m in width and
emplaced across three country rocks; volcanogenic meta-sediments, meta-andesite and
marble with sharp contacts.
The NE-SW and NW-SE tensional fractures have been reactivated as strike-slip faults
(sinistral and dextral respectively) under N-S (semi-meridional) followed by a ENE-WSW
trending regional compressional stresses creating zones of ductile deformation
characterizing coupling tectonic environment. The metamorphism in the country rocks is a
weak to very weak type that occurred under moderate pressure with depletion in silica and
enrichment in CaO and MgO restricted to marble zone.
The mineralogical study of the UDB samples reveal the presence of uranophane, beta-
uranophane, wolframite, monazite, zircon, rutile and opaques whereas pyrite is a common in
volcanogenic metasediments .
UDB is affected by a common proximal hydrothermal minerals; sericite, chlorite, pyrite and
14. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
69
ankerite. The detailed spectrometric survey revealed coincidence of eU/K and eU ratios
along the country volcanogenic metasediments rocks (reduced regime). The U migrated
from the central zones of UDB close to fault zones (channel-ways) inward to outward the
peripheries and concentrated at the NE and SW upper and lower corner.
REFERENCES
1. Abdalla, H.M., (2001): Geochemistry and origin of rare metal mineralization of Um
Safi felsite, central Eastern Desert, Egypt. Egyptian J. Geol., p. 131-149.
2. Abdel Gawad, A.M. (1964): Uranium mineralization of Atshan prospect, Eastern
Desert. A laboratory study. Unpublished report. U.A.R. Atomic Energy Establishment,
Cairo.
3. Akaad, M. K., (1996): Rock succession of the basement on autobiography and
assessment, Egypt. Geological Survey Mining Authority, 71, 87 P.
4. Akaad, M.K. and El Ramly, M.F., (1963): Geology and structure of Um Lassaf - Um
Nar iron belt, Eastern Desert of Egypt. Geol. Surv. Egypt, No. 17, 23 p.
5. Akaad, M.K., Noweir, A.M. and Abu El Ela, A.M., (1996): Geology of Pan-African
basement rocks of the Gabal Al Hadid – Wadi Mubarak District, E.D., Egypt. Geol.
Surv., Egypt. No.73, 78 p.
6. Assaf, H.S., (1973): Structure and radioactive mineralization of Wadi Arak area,
Eastern Desert, Egypt. Ph.D. Thesis, Ain Shams Univ., Cairo.
7. Date, J., Watanabe, Y., Iwaya, S. and Horiuchi, M., (1979): A consideration of the
alteration of the dacites below the Fukazawa ore deposit. Fukazawa mine, Akita,
Mining Geology, 29, 187-196.
8. Eastoe, C.J., Solomon, M. and Walshe, J.L., (1987): District-scale alteration associated
with massive sulfide deposits in the Mount Read Volcanics, Western Tasmania,
Economic Geology, 82,1239-1258.
9. El-Ghawaby, M.A., (1966): Structural and lithologic controls of localization of
radioactive mineralization in a south Qusier area. M.Sc. Thesis, Ain Shams Univ.,
Cairo, 100 p.
10. El-Ghawaby, M.A., (1973): Structural geology and radioactive mineralization of Wadi
Zeidun area, Eastern Desert of Egypt. Ph.D thesis, Ain Shams Univ., Cairo.
11. El-Manharawy, M.S., (1972): Isotopic ages and origin of some uranium bearing
volcanic rocks in Egypt. M. Sc. Thesis, Cairo Univ.
12. El-Shazly, E.M., (1977): The geology of the Egyptian region. In : The ocean basins and
margins, V. 4A (Edited by Nairn A.E., Kanes, W. H., and stehli, F.G.), P. 379-444,
New York.
13. Gifkins, C.C., and Allen, R.L., (2001): Textural and chemical characteristics of
diagenetic and hydrothermal alteration in vokanic rocks: Examples from the Mount
Read volcanics, Tasmania, Economic Geology, 96, 973-1002.
14. Hashad, A.H., Hassan, M.A. and Aboul Gadayel, A.A. (1978): Trace element variations
in the alkaline volcanics of Wadi Natash, Egypt. Bulletin Faculty Earth Science king
Abdulaziz Univ., Jeddah 2, 195-204.Hashad, A.H., and Mahfouz, S., 1976, On the
geochemistry of W. Kareim volcanics, Egypt. Chemi. Erde (Geochemistry), 35, 317-
326.
15. The 10th
International Mining, Petroleum and Metallurgical Engineering Confernece 2007; Mining,
Code No. M6
70
15. Hashad, A.H., and Mahfouz, S., (1976): On the geochemistry of W. Kareim volcanics,
Egypt. Chemi. Erde (Geochemistry), 35, 317-326.
16. Hashad, A.H., Sayyah, T.R., and El-Manharawy, M.S., (1981): Isotopic composition of
strontium and origin of W. Kareim, Eastern Desert, Egypt. Journal Geology, 25(1-2),
141-147.
17. Heikal, M.T., (2003): Model for the origin of the Um Shaghir-Um Khors alkaline
trachyte plugs, Central Eastern Desert, Egypt. The Third International Conference on
the Geology of Africa, 1, 233-253.
18. Ibrahim, M.E., Attawiya, M.Y., Osman, A.M., and Ibrahim, I.H. (2002): Occurrence of
uranium bearing minerals in Um Safi pyroclastics, Central Eastern Desert, Egypt.
Egyptian. Journal of Geology, 46-1, 39-54.
19. Ibrahim, M.E., Saleh, G.M., Ibrahim, I.H., Mostafa, M.S., Azab, M.S., Darwish, M.E.,
Asran, H.M. and Lasheen, T.A., (2005): Spectrometric and Geochemical
Characteristics of Um Doweila Bostonite, Southeastern Desert, Egypt. The 9th
inter.
Min., petrol., Metall. Engin, Conf., Cairo Univ.
20. Ishikawa Y., Sowaguch., T., Lwaya, S., and Horiuchi, M., (1976): Delineation of
prospecting targets for kuroko deposits based on modes of volcanism of underlying
dacites and alteration halos. Mining Geology, 26, 105-117.
21. Kamel, A.F., Mansour, S.I., and Ibrahim M.E., (1985): The study of the radioactive
dyke at Um Domi area, Southeastern Desert, Egypt. (Internal Report). 14 p.
22. Large, R.R., Allen, R.L., Blacke, M.D., and Herrmann, W., (2001): Hydrothermal
alteration and volatile element halos for the Rosebery klens volcanic-hosted massive
sulfide deposit, Western Tasmania, Economic Geology, 96, 1055-1072
23. Lentz, D.R., (1999): Petrology geochemistry and oxygen isotope interpretation of falsic
volcanic and related rocks hasting the massive sulfide deposits, New Brunswick,
Canada, Economic Geology, 94, 57-86.
24. Leroy, J. L. and Aniel, B.G., (1991): Uranium behavior in volcanic environments:
source-rocks and concentration mechanisms. Transport and Deposition of Metals,
Balkema, Rotterdam, 321-324.
25. Ressetars, R., Nairn, A. E. M. and Monrad, j.R., (1981): Two phases of Cretaceous-
Tertiary magmatism in the Eastern Desert of Egypt: paleomagnetic, chemical and k-Ar
evidence. Tectonophysics 73, 169-193.
26. Saleh, G.S., Ibrahim, I.H., Azab, M.S., Abdel Wahed, A.A. Ragab, A.A. and Ibrahim,
M.E., (2004): Geologic and Spectrometric Studies on Um Domi Phanerozoic Trachyte
Plug, South Eastern Desert, Egypt. The 6th
intern. Conf. On Geochemistry, Alex. Univ.,
Egypt.
27. Schardt, C., Cooke, D.R., Gemmell, J.B., and Large, R.R., (2001): Geochemcal
modeling of the zoned footwall alterationpipe. Hellyes volcanic-hosted massive sulfide
deposit, Australia, Economic Geology, 96,1037-1054.
28. Smellie, J.A.T., (1982): The mineralogy and genesis of uranium in rhyolitic ignimbrites
of Precambrian age from Duobblon, Sweden. Min. Mag., v. 46, p. 187-199.
29. Stairs, M., Morteani, G., Fuganti, A. and Drach, V., (1991): K-Ar ages, Sr-isotopic
composition and chemistry of Late Cretaceous-Tertiary basalts from the Nubian Desert
(Northern Sudan). European J. Min., 3, 943-955.