The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological...The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological units dominated by basalt and overlain by surface deposits. The surface soils vary in thickness and can be classified into well-graded SAND with silt and gravel (SW-SM), silty SAND with gravel (SM), silty GRAVEL with sand (GM), and sandy SILTY clay (CL-ML). The subsurface soil obtained from the drilled boreholes can be classified into poorly graded GRAVEL (GP), well-graded GRAVEL with sand (GW), poorly graded GRAVEL with silt (GP-GM), silty CLAYEY gravel with sand (GC-GM), silty SAND with gravel (SM), silt with SAND (ML), and silty CLAY with sand (CL-ML), sandy lean CLAY (CL), and lean CLAY (CL). The relative density of the deposit and the different gravel sizes intercalated with the soil influenced the Standard Penetration Test (SPT) values. The SPT N values are high and approach refusal even at shallow depths. The shallow refusal depth (0.10 to 0.90 m) of the Dynamic Cone Penetration Test (DCPT) was observed. Generally, the soil can be described as inactive with low plasticity and dense to very dense consistency. The basalt of the KEC site is characterized by slightly (W2) to highly (W4) weathering, their strength ranges from moderate (S4) to very strong (S2), and the Rock Quality Designation (RQD) ranges from very poor (R5) to excellent (R1). The engineering geological map of the KEC characterized the geoengineering properties of the soil and rock materials and classified them into many zones. The high sulphate (SO42−) and chloride (Cl−) contents in groundwater call for protective measures for foundation concrete. The current study revealed that geohazard(s) mitigation measures concerning floods, volcanic eruptions, and earthquakes should be considered.展开更多
Increasing demand for energy due to the populous Eastern Australia has driven oil and gas industries to find new sources of hydrocarbons as they are the primary energy suppliers.Intensive study has been done on the Vo...Increasing demand for energy due to the populous Eastern Australia has driven oil and gas industries to find new sources of hydrocarbons as they are the primary energy suppliers.Intensive study has been done on the Volador Formation in the Gippsland Basin by means of core-based petrophysical,sedimentological,and petrographic analyses as well as well log-based interpretation and capillary pressure test.Five wells from Kipper,Basker and Tuna fields with available dataset were investigated in this study:Kipper-1,Basker-1,Basker-2,Basker-5 and Tuna-4.Overall,the formation has good reservoir quality based on the high porosity and permeability values obtained through core and well log petrophysical analyses.The formation made up of mostly moderate to coarse quartz grains that has experienced strong anti-compaction and is poorly cemented.Montmorillonite and illite clays are seen dispersed in the rock formation,with the minority being mixed clays.These clays and diagenetic features including kaolinite cement and quartz overgrowth that can lead to porosity reduction only have insignificant impact on the overall reservoir quality.In addition,capillary pressure data shows that most samples are found in the transition to good reservoir zones(<50%saturation).The results obtained from this study have shown that the Volador Formation in the Gippsland Basin is worth for hydrocarbon exploration.展开更多
Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for o...Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for organic-rich shale development is still undetermined.The authors,therefore,focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin.Multiple methods were applied in this study,including thin section identification,scanning electron microscopy(SEM)observations and X-ray diffraction(XRD),and elemental analysis on outcrop samples.Five lithofacies have been defined according to the mineralogical and petrological analyses,including mudstone,bioclastic limestone,silty shale,dolomitic shale,and carbonaceous siliceous shale.The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity.The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization.High dolomite content in the study area is accompanied by high TOC,which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water.And for the area close to the Kangdian Uplift,the shale gas generation capability is comparatively favorable.The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted,and more shale gas resources in the mountain-basin transitional zone might be identified in the future.展开更多
In the French concept of deep nuclear waste repositories,the galleries should be backfilled with excavated argillite after the site has been filled.Some additives like lime could be used to improve the mechanical char...In the French concept of deep nuclear waste repositories,the galleries should be backfilled with excavated argillite after the site has been filled.Some additives like lime could be used to improve the mechanical characteristics of the argillite.After thousands of years,the degradation of the concrete lining of the galleries will generate an alkaline solution（pH value 12） that will diffuse through the backfill.This study presents the effect of a saturated Ca（OH）_2 solution circulation through lime-treated sample at 60 ℃ for 3,6 and 12 months,respectively.The effect of such circulation on the lime-treated Manois argillite（MA） was assessed by petrographical examination coupled to image analysis and scanning electron microscopy（SEM） equipped with energy dispersive X-ray（EDX） analyser of soil pieces.The objective of this study is to make the link among the mineralogical transformations,the textural and mechanical changes produced in the compacted clayey soil as a consequence of the alkaline solution circulation.展开更多
In this paper, we described the petrographical characters of the Mn-bearing rock types outcropping in the Kalakhuta, Ghatia, Gararia, Itala, Wagaicha, Tambesara and Talwara villages of Banswara district. The Mn associ...In this paper, we described the petrographical characters of the Mn-bearing rock types outcropping in the Kalakhuta, Ghatia, Gararia, Itala, Wagaicha, Tambesara and Talwara villages of Banswara district. The Mn associated rocks in the study area are phyllite, schist, quartzite and limestone. The mineral assemblage in phyllite formed under greenschist facies metamorphism. Petrographic studies of various phyllite samples also reveal that porphyroblasts of biotite sat in the fine-grained micaceous matrix (Biotite, muscovite, chlorite) along with quartz, opaque and ore minerals. Petrographic studies of schist reveal its formation under prograde metamorphism. Mineral assemblages observed in schist are typical of greenschist to lower amphibolite facies. The various schist samples at places show clusters made up of perfect rhombshaped garnets which suggest the increase in the grade of metamorphism. The quartzites are disposed conformably with the phyllites, and are at times brecciated and re-cemented by secondary chert and manganese. These Mn-bearing quartzites are with sutured/serrated and straight grain boundaries. The quartzite samples are fully composed of quartz showing undulose extinction with subordinate feldspar, micas and carbonatic materials. The petrographic characteristics explain that mostly limestones are the dolomitic composition but some ferruginous varieties are also noticed at places. The purer variety of limestone consists of calcite, dolomite and some magnetite but tremolite, quartz and some minute flakes of biotite also occur in impure variety.展开更多
The shale deposits of Damodar Valley have received great attention since preliminary studies indicate their potential for shale gas. However, fundamental information allied to shale gas re- servoir characteristics are...The shale deposits of Damodar Valley have received great attention since preliminary studies indicate their potential for shale gas. However, fundamental information allied to shale gas re- servoir characteristics are still rare in India, as exploration is in the primary stage. In this study, Ba- rakar shale beds of eastern part of Jharia Basin are evaluated for gas reservoir characteristics. It is evident that Barakar shales are carbonaceous, silty, contains sub-angular flecks of quartz and mica, irregular hair-line fractures and showing lithological variations along the bedding planes, signifying terrestrial-fluviatile deposits under reducing environment. The values of TOC varies from 1.21 wt.% to 17.32 wt.%, indicating good source rock potentiality. The vitrinite, liptinite, inertinite and mineral matter ranging from 0.28 vol.% to 12.98 vol.%, 0.17 vol.% to 3.23 vol.%, 0.23 vol.% to 9.05 vol.%, and 74.74 vol.% to 99.10 vol.%, respectively. The ternary facies plot of maceral composition substan- tiated that Barakar shales are vitrinite rich and placed in the thermal-dry gas prone region. The low values of the surface area determined following different methods point towards low methane storage capacity, this is because of diagenesis and alterations of potash feldspar responsible for pore blocking effect. The pore size distribution signifying the micro to mesoporous nature, while Type II sorption curve with the H2 type of hysteresis pattern, specifies the heterogeneity in pore structure mainly combined-slit and bottle neck pores.展开更多
To shed light on the genesis of the Dongping deposit and reveal the behaviour of CO_(2),Au and other ore elements(e.g.,Cu,Fe,Zn,As,Sb,Co etc.)in ore-forming fluids,petrographic,microthermometric and synchrotron radiat...To shed light on the genesis of the Dongping deposit and reveal the behaviour of CO_(2),Au and other ore elements(e.g.,Cu,Fe,Zn,As,Sb,Co etc.)in ore-forming fluids,petrographic,microthermometric and synchrotron radiation X-ray fluorescence(SRXRF)analyses of fluid inclusions were conducted.The ore-forming fluid is characterized as an H_(2)O-CO_(2)-NaCl system with medium-high temperatures and low salinity.Four mineralization stages are identified,namely,feldsparquartz(stage 1);pyrite-white quartz(stage 2);sulfide-smoky grey quartz(stage 3);and carbonate-quartz(stage 4).Three types of inclusions were distinguished,based on fluid composition,phase assemblages and mode of homogenization.Type A:H_(2)O-rich fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+vapour H_(2)O(VH_(2)O))at room temperature and homogenize to the liquid phase.Type B:H_(2)O-CO_(2)fluid inclusions contain 2–3 phases(liquid H_(2)O(LH_(2)O)+vapour CO_(2)(VCO_(2));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2)));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))+vapour CO_(2)(VCO_(2)))at room temperature and homogenized to the liquid H_(2)O phase.Type C:H_(2)O-CO_(2)fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))at room temperature and homogenize to a critical state.CO_(2)is clearly more enriched in the fluid inclusions of stages 2 and 3 than in stage 1.Stage 1 is dominated by type A(H_(2)O-rich)inclusions with homogenization temperatures(Th)of 220–359℃and salinities of 1.1–3.1 wt%NaCl equivalent.Type B(CO_(2)-rich)inclusions gradually increase in stages 2 and 3.The Th range of type B inclusions in stage 2 is 241–397℃with salinities of 2.2–6.9 wt%NaCl equivalent;the Th range of type A inclusions is 217–373℃with salinities of 1.2–8.1 wt%NaCl equivalent.The Th range of type B inclusions in stage 3 is 215–361℃with salinities of 2.9–6.1 wt%NaCl equivalent;the range of type A inclusions is 158–351℃with a salinity of 0.7–5.5 wt%NaCl equivalent.Stage 4 is characterized by type A with Th of 151–250℃and salinities of 0.9–8.3 wt%NaCl equivalent.The mapping results show that elements As,Te and Sb are more concentrated in vapour CO_(2)than in liquid H_(2)O at room temperature,which suggests that vapour components are more able to transport elements when phase separation occurs.The SRXRF quantitative results show that Au,Cl,S and some other metals are obviously more enriched in the fluid inclusions of stages 2 and 3 than those in stage 1.Additionally,the contents of S in stages 1–3 are much lower than those of Cl,which suggests that gold might migrate mainly in the form of a gold-chloride complex.Au is more enriched in type B fluid inclusions than in type A fluid inclusions,which suggests that the enrichment and migration of gold are closely related to CO_(2)and CO_(2)plays a critical role in the migration and enrichment of gold.The trace elements in the fluid have a similar change trend to those in the Yanshanian syenogranite distributed in the southeastern part of the mining area,which may provide some evidence for an intrusion-related genesis for the Dongping gold deposit.展开更多
The slag melting characteristic of slag forming and slag splashing for 300 t BOF less slag process is researched by combining the methods of the slag chemical composition, the melting point determination and the petro...The slag melting characteristic of slag forming and slag splashing for 300 t BOF less slag process is researched by combining the methods of the slag chemical composition, the melting point determination and the petrographic analysis. The results show that the melting point of final slag for less slag smelting is 20 ~C lower than that for conventional smelting. According to results of the petrographic analysis, the C3S （3CaO ~ SiO2） and C2S （2CaO · SiO2） content for less slag smelting are lower than those for conventional smelting, while the RO （FeO, MgO, MnO, etc） phase and C4AF （4CaO · Al2O3· Fe2O3） phase are higher than those for conventional smelting. According to results of the chemical analysis, the （CaO） content and slag basicity for less slag smelting are higher than those for conventional smelting, while （FeO） and （MgO） content in slag for less slag smelting are almost equal to those for conventional smelting. The reason why slag melting point for less slag smelting is lower than that for con- ventional smelting is that the quantity of added fluorite for less slag smelting is more than that for conventional smel- ting. According tO the analysis results the slag melting point is determined by the C3S, C2S, RO phase and C4AF content. According to the results of slag melting characteristic before and after slag splashing for less slag smelting, the present adjusting slag process has little effect. It is important to adjust the composition of BOF final slag. The （FeO） content in slag is to be reduced at the slag splashing and adjusting slag process for less slag smelting.展开更多
Studies were taken of ore-bearing rocks, ores and gravity concentrates from Natalka gold deposit by a set of complex methods including mineralogical, petrographic and geochemical research, gravity concentration, and e...Studies were taken of ore-bearing rocks, ores and gravity concentrates from Natalka gold deposit by a set of complex methods including mineralogical, petrographic and geochemical research, gravity concentration, and electronic microscopy. The major form of Au found is native: free gold is larger and dispersed, in the form of microinclusions. The obtained results are the basis for an effective technology to extract gold and sequence of profitable mining of Natalka deposit.展开更多
All engineering projects consist of several steps, and one of the main tasks is to identify and characterize the most important features of rock types that will be excavated, crushed, or mined for any particular usage...All engineering projects consist of several steps, and one of the main tasks is to identify and characterize the most important features of rock types that will be excavated, crushed, or mined for any particular usage purpose, from a single residential building to major works of infrastructure. Laboratory investigation on engineering geology is thus conducted in order to determine the most relevant rock properties when designing structures such as mining shafts, tunnels, buildings, or reservoir dams to be built in sites associated with rocks. A wide range of laboratory tests is available, making the correct choice of test methods greatly relevant to determine the key property for the planned use of the rock. This paper is an illustrative case of laboratory testing of basaltic rocks to be used as riprap in a reservoir dam. It shows the important role of the petrographic study carried out to analyze the distribution pattern of smectite clay minerals. Test results are explained for the assessment of rock alterability, an essential aspect for the selection of the most suitable basalt variety for the envisaged conditions of use.展开更多
In this paper,the strength and petrographic structure of clinker by low-temperature burning are studied.The results show that both the calcining temperature of Ca-CO3 and sintering temperature clinker decreases by 150...In this paper,the strength and petrographic structure of clinker by low-temperature burning are studied.The results show that both the calcining temperature of Ca-CO3 and sintering temperature clinker decreases by 150 degrees C compared with those in traditional rotary kiln,the rate of f-CaO in the clinker sintered at 1300 degrees C is 0.29%similar to 2.81%,the strength of the clinker is 62.5MPa with maximum 69.4MPa at a specific area of 2900 similar to 3400cm(2)/g.The results also show that the types of petrographic structure of the clinker can be classified as:homogeneous structure,inlaid or edged structure,stain-melting structure and porous structure.The clinker sintered at 1300+/-15 degrees C temperature and with enough retention period is mainly in homogeneous structure.展开更多
To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of China, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactiv...To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of China, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactivity of these aggregates were systematically investigated. On one hand, petrographic examination of aggregates, combined with X-ray diffraction analysis, chemical analysis, scanning electron microscopy, was conducted for analyzing their mineralogy and texture. It was found that not only mineral characteristics, but also their interior structure would affect their potential alkali-silica reactivity. Furthermore, the alkali-silica reactivity of aggregates is due to their mineral compositions, such as containing different alkali-reactive minerals, while, different stuctures of those aggregates with similar minerals affect their reactivity to some extent. There are some amount of micro-aperture and cracks across the quartz in the aggregate, which may become the natural accesses for Na^＋, K^＋, and OH^- ions to intrude in the mortar or concrete during the process of alkali-silica reaction. Alkali-silica reactivity of the aggregates was detected by the accelerated mortar bars test. It was revealed that all the aggregates tested were alkali-silica reactive and the results were also in accordance with their mineral and structure analysis.展开更多
A new method of sintering Ca3SiO5 by the combination of conventional and microwave heating methods was studied. The influence of transitional metal oxides such as Fe2O3, Cr2O3, MnO2, and V2O5 used as the additive of m...A new method of sintering Ca3SiO5 by the combination of conventional and microwave heating methods was studied. The influence of transitional metal oxides such as Fe2O3, Cr2O3, MnO2, and V2O5 used as the additive of microwave absorption on the microwave-promoted burning of Ca3SiO5 was investigated. The experimental results indicate that the new burning technique is capable of promoting the sintering of Ca3SiO5. At 1200-1300℃ in an electric furnace, Ca3SiO5 can be obtained only when the sample is heated in a microwave for 110-240 s, and the free lime content is below 40wt%. Based on the experiments, Fe2O3, Cr2O3, MnO2, and V2O5 can enhance microwave sintering. Amongst them, Cr2O3 is the most effective. The characteristic of the X-ray diffraction peaks of Ca3SiO5 is similar to those of standard Ca3SiO5, but the peaks are wider.展开更多
The variation regularity of coke strength was investigated in terms of the genetic factors and petrographic parameters of coal in collaboration with the technical properties of coal. A concept of inert holding ratio o...The variation regularity of coke strength was investigated in terms of the genetic factors and petrographic parameters of coal in collaboration with the technical properties of coal. A concept of inert holding ratio of coal was proposed. There is an optimal inert holding ratio for different ranks of coals for making coke with highest combined strength. The additive property of inert holding ratio under normal conditions was demonstrated with actual examples of coal blending.Thus it is possible to predict the combined strength of coke through reflectance, content of inert components and caking index diagram system.展开更多
Geotechnical studies were carried out on soils from Shango-Chanchaga highway in Minna, in relation to the petrographic characteristics of the parent rock. Samples were obtained from 5 trial pits at 1 km interval for g...Geotechnical studies were carried out on soils from Shango-Chanchaga highway in Minna, in relation to the petrographic characteristics of the parent rock. Samples were obtained from 5 trial pits at 1 km interval for geotechnical analysis. The moisture content varies from 35.0% to 58.5%, liquid limit ranges from 29.0% to 43.0%, plastic limit ranges between 9.0% and 26.5%, while plasticity index ranges from 12.0 to 33.5. The optimum moisture content (OMC) ranges from 12.0 to 14.0, and California Bearing Ratio (CBR) ranges from 2 to 21. The diffractograms showed that the dominant minerals were clinochore (Mg,Fe)6(Si,Al)4O10(OH)8, quartz (SiO2), cordierite (Mg2Al4Si5O18Ar0.625), and albite (Na0.98Ca0.02Al1.02Si2.98O18). The results showed that there exists a relationship between the mineral composition, the texture of the rock, and the geotechnical characteristics of the soil types.展开更多
Cases of degradation of concrete associated to iron sulphides in aggregates were recently recognized in the Trois-Rivi6res area, Canada. The aggregate used to produce concrete was an anorthositic gabbro containing var...Cases of degradation of concrete associated to iron sulphides in aggregates were recently recognized in the Trois-Rivi6res area, Canada. The aggregate used to produce concrete was an anorthositic gabbro containing various proportions of pyrite, pyrrhotite, chalcopyrite and pentlandite. Quantitative microanalysis on sulphide minerals show that pyrrhotite contains small amount of Ni, Co, Cu and As substituting for Fe in the mineral structure. Considering element substitution, x value in the chemical formula （Fe~.xS） was calculated to 0.099 in the pyrrhotite studied. Petrographic examination of damaged concretes showed the presence of oxidized pyrrhotite. The observation of polished samples shows, in several cases, that the pyrite is intact while the pyrrhotite presents evident signs of oxidation. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste and provokes the formation of gypsum and ettringite. These minerals were observed by SEM-EDS （scanning electron microscope/energy dispersive x-ray spectrometer） and their precipitation causes a volume increase that creates expansion and cracking of the concrete.展开更多
Formulating the original composition of weathered tephra can be a chaUenging task. A previous study by Wadia （1998 and 2007） demonstrated the enrichment of silica according to the hypothesis that the percentage of a...Formulating the original composition of weathered tephra can be a chaUenging task. A previous study by Wadia （1998 and 2007） demonstrated the enrichment of silica according to the hypothesis that the percentage of aluminum oxide remains constant within the unweathered parent material and its weathered counterpart （Faure, 1991）, which indicated the average enrichment of silica to be 6.5%. This study demonstrates the enrichment of microcrystalline-cryptocrystalline quartz in the Reid＇s Mistake Formation of the Newcastle Coal measures of Sydney Basin, Australia, incorporating petrographic analyses and MBC （mass balance calculations） using trace element zircon as the immobile element. For MBC, zircon is more favorable, as it is a trace element that tends to be immobile during the process of chemical weathering. The composition of the unweathered reference samples was collected from the Tertiary volcanic complexes of Northeastern New South Wales and Southeastern Queensland. ICP-AES （inductively coupled plasma-atomic emission spectroscopy） was used to determine the chemical composition of the weathered samples. The quantitative enrichment of silica was provided by performing MBC using zircon as the immobile trace element. The petrographic analyses results indicated that the tephra was subjected to chemical weathering in a meteoric regime, as represented by minerals observed in the weathered tephra. The silica enrichment by MBC involving zircon resulted in 40.11%, which is indicative of chemical weathering, and was additionally supported by the presence of chert lenses in the volcanic horizon, indicating the enrichment of silica as a result of chemical weathering.展开更多
This paper presents the results of petrographic study of sedimentary iron ore from surface strata of the Shendi-Atbara Basin,River Nile State,Sudan.The aims of this study are to investigate the geological behavior and...This paper presents the results of petrographic study of sedimentary iron ore from surface strata of the Shendi-Atbara Basin,River Nile State,Sudan.The aims of this study are to investigate the geological behavior and geological conditions affecting precipitation of sedimentary iron ore.The methodologies have been used to realize the objectives of this study include field work,office work and laboratory work including thin sections and polished sections analysis.According to field observation sedimentary iron ore can broadly be considered as occurring in three major classes:Ferribands iron,ferricrete iron and oolitic iron ores.The modes of occurrence of iron ore were described at the outcrops and vertical sedimentary profiles revealed that the iron occurred in the study area at different types in stratigraphic sequence such as cap,bedded and interbedded conformable with Shendi Formation.Petrographic study of iron ore in collected samples using polarized microscope and ore microscope includes study of the textures and structures of ores to obtain ore history.The main types of textures and structures in studied samples are oolitic,granular,lamellar and bands.According to these results the origin of iron ore is formed by chemical precipitation during chemical weathering of surrounding areas in continental lacustrine environment.The iron ore in study area is potential for future mining works and steel industry.展开更多
Zatua Hills are located at Haut Uélé Province of Democratic Republic of Congo (DRC), between northern Bafwasende and southern Paulis (Isiro) Squarred Degrees. Belonging to greenstone belt of Ngayu, that area...Zatua Hills are located at Haut Uélé Province of Democratic Republic of Congo (DRC), between northern Bafwasende and southern Paulis (Isiro) Squarred Degrees. Belonging to greenstone belt of Ngayu, that area is identified by the high elevated zone which is remained the witness of stable zone, not affected by the ancienst erosion process. Zatua Hills are in the superior Kibalian formation dated to Neoarchaen, hosted in Upper Congo Granites Massifs of DRC covering a large central zone of NE of DRC, and consisting to dolerite, phyllade, clay rich sediment, poor Banded Iron Formations (BIFs), enriched BIFs, friable hematite, hard hematite, mineralized and unmineralized brechias. Magnetite, martite and hematite are associated to some secondary minerals such as goethite, gibbsite, kaolinite, strengite, variscite and others clay minerals present in BIFs. Petrographic analysis made from the samples collected in situ showed, as well as BIFs and iron ore associated, that magnetite was much abundant oxide mineral which is oxided to martite before to stabilize to hematite during the deposition time. Having about hundred meters of thickness, the rich iron ore of this area content, in the majority less deleterious elements which, are harmful in metallurgic process of iron. These secondary minerals were precipitated at various degrees in the leached cavities of rocks between martite and hematite aggregates to botryoidal texture and, are rich to Al, and are mainly consisting to gibbsite and solid solution series of variscite-strengite (AlPO<sub>4</sub>·2H<sub>2</sub>O and FePO<sub>4</sub>·2H<sub>2</sub>O). Low degree of metamorphism played when magnetite was converted to martite, with the presence of variscite and anatase like witnesses of this event in which, martite was crystalized to hematite.展开更多
Most of the hinterland of the North China platform is devoid of Late Ordovician strata. The BaiyanhuaMountain section at Shetai Town is a standard section of the Upper Ordovician newly established in recentyears at th...Most of the hinterland of the North China platform is devoid of Late Ordovician strata. The BaiyanhuaMountain section at Shetai Town is a standard section of the Upper Ordovician newly established in recentyears at the northernmost margin of the platform. This establishment directly involved the determination of thenorth boundary of the platform and the understanding of its evolutionary Listory. The area is quite differentfrom the binterland of the platform in Middle Ordovician rock types and sedimentary environments, with theformer characterized by frequent slope deposits and the latter consisting almost entirely of platform deposits.The present paper focuses on the petrographic features and sedimentary ervironments of the Middle-UpperOrdovician strata in the area, providing further theoretical support to the establishment of the section and fil-ling the gap in this respect.展开更多
文摘The Knowledge Economic City (KEC) of Al Madinah Al Munawwarah is one of the major projects and represents the cornerstone for the new development activities for Al Madinah. The study area contains different geological units dominated by basalt and overlain by surface deposits. The surface soils vary in thickness and can be classified into well-graded SAND with silt and gravel (SW-SM), silty SAND with gravel (SM), silty GRAVEL with sand (GM), and sandy SILTY clay (CL-ML). The subsurface soil obtained from the drilled boreholes can be classified into poorly graded GRAVEL (GP), well-graded GRAVEL with sand (GW), poorly graded GRAVEL with silt (GP-GM), silty CLAYEY gravel with sand (GC-GM), silty SAND with gravel (SM), silt with SAND (ML), and silty CLAY with sand (CL-ML), sandy lean CLAY (CL), and lean CLAY (CL). The relative density of the deposit and the different gravel sizes intercalated with the soil influenced the Standard Penetration Test (SPT) values. The SPT N values are high and approach refusal even at shallow depths. The shallow refusal depth (0.10 to 0.90 m) of the Dynamic Cone Penetration Test (DCPT) was observed. Generally, the soil can be described as inactive with low plasticity and dense to very dense consistency. The basalt of the KEC site is characterized by slightly (W2) to highly (W4) weathering, their strength ranges from moderate (S4) to very strong (S2), and the Rock Quality Designation (RQD) ranges from very poor (R5) to excellent (R1). The engineering geological map of the KEC characterized the geoengineering properties of the soil and rock materials and classified them into many zones. The high sulphate (SO42−) and chloride (Cl−) contents in groundwater call for protective measures for foundation concrete. The current study revealed that geohazard(s) mitigation measures concerning floods, volcanic eruptions, and earthquakes should be considered.
文摘Increasing demand for energy due to the populous Eastern Australia has driven oil and gas industries to find new sources of hydrocarbons as they are the primary energy suppliers.Intensive study has been done on the Volador Formation in the Gippsland Basin by means of core-based petrophysical,sedimentological,and petrographic analyses as well as well log-based interpretation and capillary pressure test.Five wells from Kipper,Basker and Tuna fields with available dataset were investigated in this study:Kipper-1,Basker-1,Basker-2,Basker-5 and Tuna-4.Overall,the formation has good reservoir quality based on the high porosity and permeability values obtained through core and well log petrophysical analyses.The formation made up of mostly moderate to coarse quartz grains that has experienced strong anti-compaction and is poorly cemented.Montmorillonite and illite clays are seen dispersed in the rock formation,with the minority being mixed clays.These clays and diagenetic features including kaolinite cement and quartz overgrowth that can lead to porosity reduction only have insignificant impact on the overall reservoir quality.In addition,capillary pressure data shows that most samples are found in the transition to good reservoir zones(<50%saturation).The results obtained from this study have shown that the Volador Formation in the Gippsland Basin is worth for hydrocarbon exploration.
基金jointly funded by the National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLC20210104)China Geological Survey(DD20221661)China National Science and Technology Major Project“Test and Application of Shale Gas Exploration and Evaluation Technology(2016ZX05034004)”。
文摘Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for organic-rich shale development is still undetermined.The authors,therefore,focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin.Multiple methods were applied in this study,including thin section identification,scanning electron microscopy(SEM)observations and X-ray diffraction(XRD),and elemental analysis on outcrop samples.Five lithofacies have been defined according to the mineralogical and petrological analyses,including mudstone,bioclastic limestone,silty shale,dolomitic shale,and carbonaceous siliceous shale.The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity.The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization.High dolomite content in the study area is accompanied by high TOC,which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water.And for the area close to the Kangdian Uplift,the shale gas generation capability is comparatively favorable.The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted,and more shale gas resources in the mountain-basin transitional zone might be identified in the future.
文摘In the French concept of deep nuclear waste repositories,the galleries should be backfilled with excavated argillite after the site has been filled.Some additives like lime could be used to improve the mechanical characteristics of the argillite.After thousands of years,the degradation of the concrete lining of the galleries will generate an alkaline solution（pH value 12） that will diffuse through the backfill.This study presents the effect of a saturated Ca（OH）_2 solution circulation through lime-treated sample at 60 ℃ for 3,6 and 12 months,respectively.The effect of such circulation on the lime-treated Manois argillite（MA） was assessed by petrographical examination coupled to image analysis and scanning electron microscopy（SEM） equipped with energy dispersive X-ray（EDX） analyser of soil pieces.The objective of this study is to make the link among the mineralogical transformations,the textural and mechanical changes produced in the compacted clayey soil as a consequence of the alkaline solution circulation.
文摘In this paper, we described the petrographical characters of the Mn-bearing rock types outcropping in the Kalakhuta, Ghatia, Gararia, Itala, Wagaicha, Tambesara and Talwara villages of Banswara district. The Mn associated rocks in the study area are phyllite, schist, quartzite and limestone. The mineral assemblage in phyllite formed under greenschist facies metamorphism. Petrographic studies of various phyllite samples also reveal that porphyroblasts of biotite sat in the fine-grained micaceous matrix (Biotite, muscovite, chlorite) along with quartz, opaque and ore minerals. Petrographic studies of schist reveal its formation under prograde metamorphism. Mineral assemblages observed in schist are typical of greenschist to lower amphibolite facies. The various schist samples at places show clusters made up of perfect rhombshaped garnets which suggest the increase in the grade of metamorphism. The quartzites are disposed conformably with the phyllites, and are at times brecciated and re-cemented by secondary chert and manganese. These Mn-bearing quartzites are with sutured/serrated and straight grain boundaries. The quartzite samples are fully composed of quartz showing undulose extinction with subordinate feldspar, micas and carbonatic materials. The petrographic characteristics explain that mostly limestones are the dolomitic composition but some ferruginous varieties are also noticed at places. The purer variety of limestone consists of calcite, dolomite and some magnetite but tremolite, quartz and some minute flakes of biotite also occur in impure variety.
基金Ministry of Coal for funding support of the project entitled "Shale gas potentiality eva luation of Damodar Basin of India" (Coal S & T grant: CE(Eo I)/30) under the research work has been carried out
文摘The shale deposits of Damodar Valley have received great attention since preliminary studies indicate their potential for shale gas. However, fundamental information allied to shale gas re- servoir characteristics are still rare in India, as exploration is in the primary stage. In this study, Ba- rakar shale beds of eastern part of Jharia Basin are evaluated for gas reservoir characteristics. It is evident that Barakar shales are carbonaceous, silty, contains sub-angular flecks of quartz and mica, irregular hair-line fractures and showing lithological variations along the bedding planes, signifying terrestrial-fluviatile deposits under reducing environment. The values of TOC varies from 1.21 wt.% to 17.32 wt.%, indicating good source rock potentiality. The vitrinite, liptinite, inertinite and mineral matter ranging from 0.28 vol.% to 12.98 vol.%, 0.17 vol.% to 3.23 vol.%, 0.23 vol.% to 9.05 vol.%, and 74.74 vol.% to 99.10 vol.%, respectively. The ternary facies plot of maceral composition substan- tiated that Barakar shales are vitrinite rich and placed in the thermal-dry gas prone region. The low values of the surface area determined following different methods point towards low methane storage capacity, this is because of diagenesis and alterations of potash feldspar responsible for pore blocking effect. The pore size distribution signifying the micro to mesoporous nature, while Type II sorption curve with the H2 type of hysteresis pattern, specifies the heterogeneity in pore structure mainly combined-slit and bottle neck pores.
基金funded by a Natural Science Foundation of Hebei Province(Grant No.D2020403019)the Natural Science Foundation of Hebei Province(Grant Nos.D2020403101 and D2019403041)+2 种基金the Science and Technology Project of Hebei Education Department(Grant No.ZD2020134)the National Natural Science Foundation of China(Grant Nos.41702094 and 41672070)the Science and Technology Innovation Team Project of Hebei GEO University(Grant No.KJCXTD-2021-02)。
文摘To shed light on the genesis of the Dongping deposit and reveal the behaviour of CO_(2),Au and other ore elements(e.g.,Cu,Fe,Zn,As,Sb,Co etc.)in ore-forming fluids,petrographic,microthermometric and synchrotron radiation X-ray fluorescence(SRXRF)analyses of fluid inclusions were conducted.The ore-forming fluid is characterized as an H_(2)O-CO_(2)-NaCl system with medium-high temperatures and low salinity.Four mineralization stages are identified,namely,feldsparquartz(stage 1);pyrite-white quartz(stage 2);sulfide-smoky grey quartz(stage 3);and carbonate-quartz(stage 4).Three types of inclusions were distinguished,based on fluid composition,phase assemblages and mode of homogenization.Type A:H_(2)O-rich fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+vapour H_(2)O(VH_(2)O))at room temperature and homogenize to the liquid phase.Type B:H_(2)O-CO_(2)fluid inclusions contain 2–3 phases(liquid H_(2)O(LH_(2)O)+vapour CO_(2)(VCO_(2));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2)));liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))+vapour CO_(2)(VCO_(2)))at room temperature and homogenized to the liquid H_(2)O phase.Type C:H_(2)O-CO_(2)fluid inclusions show 2 phases(liquid H_(2)O(LH_(2)O)+liquid CO_(2)(LCO_(2))at room temperature and homogenize to a critical state.CO_(2)is clearly more enriched in the fluid inclusions of stages 2 and 3 than in stage 1.Stage 1 is dominated by type A(H_(2)O-rich)inclusions with homogenization temperatures(Th)of 220–359℃and salinities of 1.1–3.1 wt%NaCl equivalent.Type B(CO_(2)-rich)inclusions gradually increase in stages 2 and 3.The Th range of type B inclusions in stage 2 is 241–397℃with salinities of 2.2–6.9 wt%NaCl equivalent;the Th range of type A inclusions is 217–373℃with salinities of 1.2–8.1 wt%NaCl equivalent.The Th range of type B inclusions in stage 3 is 215–361℃with salinities of 2.9–6.1 wt%NaCl equivalent;the range of type A inclusions is 158–351℃with a salinity of 0.7–5.5 wt%NaCl equivalent.Stage 4 is characterized by type A with Th of 151–250℃and salinities of 0.9–8.3 wt%NaCl equivalent.The mapping results show that elements As,Te and Sb are more concentrated in vapour CO_(2)than in liquid H_(2)O at room temperature,which suggests that vapour components are more able to transport elements when phase separation occurs.The SRXRF quantitative results show that Au,Cl,S and some other metals are obviously more enriched in the fluid inclusions of stages 2 and 3 than those in stage 1.Additionally,the contents of S in stages 1–3 are much lower than those of Cl,which suggests that gold might migrate mainly in the form of a gold-chloride complex.Au is more enriched in type B fluid inclusions than in type A fluid inclusions,which suggests that the enrichment and migration of gold are closely related to CO_(2)and CO_(2)plays a critical role in the migration and enrichment of gold.The trace elements in the fluid have a similar change trend to those in the Yanshanian syenogranite distributed in the southeastern part of the mining area,which may provide some evidence for an intrusion-related genesis for the Dongping gold deposit.
基金Item Sponsored by National Science and Technology Support Program for 11th Five-Year Plan of China(2006BAE03A00)
文摘The slag melting characteristic of slag forming and slag splashing for 300 t BOF less slag process is researched by combining the methods of the slag chemical composition, the melting point determination and the petrographic analysis. The results show that the melting point of final slag for less slag smelting is 20 ~C lower than that for conventional smelting. According to results of the petrographic analysis, the C3S （3CaO ~ SiO2） and C2S （2CaO · SiO2） content for less slag smelting are lower than those for conventional smelting, while the RO （FeO, MgO, MnO, etc） phase and C4AF （4CaO · Al2O3· Fe2O3） phase are higher than those for conventional smelting. According to results of the chemical analysis, the （CaO） content and slag basicity for less slag smelting are higher than those for conventional smelting, while （FeO） and （MgO） content in slag for less slag smelting are almost equal to those for conventional smelting. The reason why slag melting point for less slag smelting is lower than that for con- ventional smelting is that the quantity of added fluorite for less slag smelting is more than that for conventional smel- ting. According tO the analysis results the slag melting point is determined by the C3S, C2S, RO phase and C4AF content. According to the results of slag melting characteristic before and after slag splashing for less slag smelting, the present adjusting slag process has little effect. It is important to adjust the composition of BOF final slag. The （FeO） content in slag is to be reduced at the slag splashing and adjusting slag process for less slag smelting.
文摘Studies were taken of ore-bearing rocks, ores and gravity concentrates from Natalka gold deposit by a set of complex methods including mineralogical, petrographic and geochemical research, gravity concentration, and electronic microscopy. The major form of Au found is native: free gold is larger and dispersed, in the form of microinclusions. The obtained results are the basis for an effective technology to extract gold and sequence of profitable mining of Natalka deposit.
文摘All engineering projects consist of several steps, and one of the main tasks is to identify and characterize the most important features of rock types that will be excavated, crushed, or mined for any particular usage purpose, from a single residential building to major works of infrastructure. Laboratory investigation on engineering geology is thus conducted in order to determine the most relevant rock properties when designing structures such as mining shafts, tunnels, buildings, or reservoir dams to be built in sites associated with rocks. A wide range of laboratory tests is available, making the correct choice of test methods greatly relevant to determine the key property for the planned use of the rock. This paper is an illustrative case of laboratory testing of basaltic rocks to be used as riprap in a reservoir dam. It shows the important role of the petrographic study carried out to analyze the distribution pattern of smectite clay minerals. Test results are explained for the assessment of rock alterability, an essential aspect for the selection of the most suitable basalt variety for the envisaged conditions of use.
文摘In this paper,the strength and petrographic structure of clinker by low-temperature burning are studied.The results show that both the calcining temperature of Ca-CO3 and sintering temperature clinker decreases by 150 degrees C compared with those in traditional rotary kiln,the rate of f-CaO in the clinker sintered at 1300 degrees C is 0.29%similar to 2.81%,the strength of the clinker is 62.5MPa with maximum 69.4MPa at a specific area of 2900 similar to 3400cm(2)/g.The results also show that the types of petrographic structure of the clinker can be classified as:homogeneous structure,inlaid or edged structure,stain-melting structure and porous structure.The clinker sintered at 1300+/-15 degrees C temperature and with enough retention period is mainly in homogeneous structure.
基金Funded by the State "Key Base Development Foudation" Project("973") of China(201CD610706)Natural Science Foundation of Jiangsu Province,China(2007191SB90098)+1 种基金Analysis and Testing Method Projext of Department of Natural Science Foundation of Jiangsu Provice, China (2006191TS90140)the Scientific Research Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China (2006191XLH0132)
文摘To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of China, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactivity of these aggregates were systematically investigated. On one hand, petrographic examination of aggregates, combined with X-ray diffraction analysis, chemical analysis, scanning electron microscopy, was conducted for analyzing their mineralogy and texture. It was found that not only mineral characteristics, but also their interior structure would affect their potential alkali-silica reactivity. Furthermore, the alkali-silica reactivity of aggregates is due to their mineral compositions, such as containing different alkali-reactive minerals, while, different stuctures of those aggregates with similar minerals affect their reactivity to some extent. There are some amount of micro-aperture and cracks across the quartz in the aggregate, which may become the natural accesses for Na^＋, K^＋, and OH^- ions to intrude in the mortar or concrete during the process of alkali-silica reaction. Alkali-silica reactivity of the aggregates was detected by the accelerated mortar bars test. It was revealed that all the aggregates tested were alkali-silica reactive and the results were also in accordance with their mineral and structure analysis.
文摘A new method of sintering Ca3SiO5 by the combination of conventional and microwave heating methods was studied. The influence of transitional metal oxides such as Fe2O3, Cr2O3, MnO2, and V2O5 used as the additive of microwave absorption on the microwave-promoted burning of Ca3SiO5 was investigated. The experimental results indicate that the new burning technique is capable of promoting the sintering of Ca3SiO5. At 1200-1300℃ in an electric furnace, Ca3SiO5 can be obtained only when the sample is heated in a microwave for 110-240 s, and the free lime content is below 40wt%. Based on the experiments, Fe2O3, Cr2O3, MnO2, and V2O5 can enhance microwave sintering. Amongst them, Cr2O3 is the most effective. The characteristic of the X-ray diffraction peaks of Ca3SiO5 is similar to those of standard Ca3SiO5, but the peaks are wider.
文摘The variation regularity of coke strength was investigated in terms of the genetic factors and petrographic parameters of coal in collaboration with the technical properties of coal. A concept of inert holding ratio of coal was proposed. There is an optimal inert holding ratio for different ranks of coals for making coke with highest combined strength. The additive property of inert holding ratio under normal conditions was demonstrated with actual examples of coal blending.Thus it is possible to predict the combined strength of coke through reflectance, content of inert components and caking index diagram system.
文摘Geotechnical studies were carried out on soils from Shango-Chanchaga highway in Minna, in relation to the petrographic characteristics of the parent rock. Samples were obtained from 5 trial pits at 1 km interval for geotechnical analysis. The moisture content varies from 35.0% to 58.5%, liquid limit ranges from 29.0% to 43.0%, plastic limit ranges between 9.0% and 26.5%, while plasticity index ranges from 12.0 to 33.5. The optimum moisture content (OMC) ranges from 12.0 to 14.0, and California Bearing Ratio (CBR) ranges from 2 to 21. The diffractograms showed that the dominant minerals were clinochore (Mg,Fe)6(Si,Al)4O10(OH)8, quartz (SiO2), cordierite (Mg2Al4Si5O18Ar0.625), and albite (Na0.98Ca0.02Al1.02Si2.98O18). The results showed that there exists a relationship between the mineral composition, the texture of the rock, and the geotechnical characteristics of the soil types.
文摘Cases of degradation of concrete associated to iron sulphides in aggregates were recently recognized in the Trois-Rivi6res area, Canada. The aggregate used to produce concrete was an anorthositic gabbro containing various proportions of pyrite, pyrrhotite, chalcopyrite and pentlandite. Quantitative microanalysis on sulphide minerals show that pyrrhotite contains small amount of Ni, Co, Cu and As substituting for Fe in the mineral structure. Considering element substitution, x value in the chemical formula （Fe~.xS） was calculated to 0.099 in the pyrrhotite studied. Petrographic examination of damaged concretes showed the presence of oxidized pyrrhotite. The observation of polished samples shows, in several cases, that the pyrite is intact while the pyrrhotite presents evident signs of oxidation. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste and provokes the formation of gypsum and ettringite. These minerals were observed by SEM-EDS （scanning electron microscope/energy dispersive x-ray spectrometer） and their precipitation causes a volume increase that creates expansion and cracking of the concrete.
文摘Formulating the original composition of weathered tephra can be a chaUenging task. A previous study by Wadia （1998 and 2007） demonstrated the enrichment of silica according to the hypothesis that the percentage of aluminum oxide remains constant within the unweathered parent material and its weathered counterpart （Faure, 1991）, which indicated the average enrichment of silica to be 6.5%. This study demonstrates the enrichment of microcrystalline-cryptocrystalline quartz in the Reid＇s Mistake Formation of the Newcastle Coal measures of Sydney Basin, Australia, incorporating petrographic analyses and MBC （mass balance calculations） using trace element zircon as the immobile element. For MBC, zircon is more favorable, as it is a trace element that tends to be immobile during the process of chemical weathering. The composition of the unweathered reference samples was collected from the Tertiary volcanic complexes of Northeastern New South Wales and Southeastern Queensland. ICP-AES （inductively coupled plasma-atomic emission spectroscopy） was used to determine the chemical composition of the weathered samples. The quantitative enrichment of silica was provided by performing MBC using zircon as the immobile trace element. The petrographic analyses results indicated that the tephra was subjected to chemical weathering in a meteoric regime, as represented by minerals observed in the weathered tephra. The silica enrichment by MBC involving zircon resulted in 40.11%, which is indicative of chemical weathering, and was additionally supported by the presence of chert lenses in the volcanic horizon, indicating the enrichment of silica as a result of chemical weathering.
文摘This paper presents the results of petrographic study of sedimentary iron ore from surface strata of the Shendi-Atbara Basin,River Nile State,Sudan.The aims of this study are to investigate the geological behavior and geological conditions affecting precipitation of sedimentary iron ore.The methodologies have been used to realize the objectives of this study include field work,office work and laboratory work including thin sections and polished sections analysis.According to field observation sedimentary iron ore can broadly be considered as occurring in three major classes:Ferribands iron,ferricrete iron and oolitic iron ores.The modes of occurrence of iron ore were described at the outcrops and vertical sedimentary profiles revealed that the iron occurred in the study area at different types in stratigraphic sequence such as cap,bedded and interbedded conformable with Shendi Formation.Petrographic study of iron ore in collected samples using polarized microscope and ore microscope includes study of the textures and structures of ores to obtain ore history.The main types of textures and structures in studied samples are oolitic,granular,lamellar and bands.According to these results the origin of iron ore is formed by chemical precipitation during chemical weathering of surrounding areas in continental lacustrine environment.The iron ore in study area is potential for future mining works and steel industry.
文摘Zatua Hills are located at Haut Uélé Province of Democratic Republic of Congo (DRC), between northern Bafwasende and southern Paulis (Isiro) Squarred Degrees. Belonging to greenstone belt of Ngayu, that area is identified by the high elevated zone which is remained the witness of stable zone, not affected by the ancienst erosion process. Zatua Hills are in the superior Kibalian formation dated to Neoarchaen, hosted in Upper Congo Granites Massifs of DRC covering a large central zone of NE of DRC, and consisting to dolerite, phyllade, clay rich sediment, poor Banded Iron Formations (BIFs), enriched BIFs, friable hematite, hard hematite, mineralized and unmineralized brechias. Magnetite, martite and hematite are associated to some secondary minerals such as goethite, gibbsite, kaolinite, strengite, variscite and others clay minerals present in BIFs. Petrographic analysis made from the samples collected in situ showed, as well as BIFs and iron ore associated, that magnetite was much abundant oxide mineral which is oxided to martite before to stabilize to hematite during the deposition time. Having about hundred meters of thickness, the rich iron ore of this area content, in the majority less deleterious elements which, are harmful in metallurgic process of iron. These secondary minerals were precipitated at various degrees in the leached cavities of rocks between martite and hematite aggregates to botryoidal texture and, are rich to Al, and are mainly consisting to gibbsite and solid solution series of variscite-strengite (AlPO<sub>4</sub>·2H<sub>2</sub>O and FePO<sub>4</sub>·2H<sub>2</sub>O). Low degree of metamorphism played when magnetite was converted to martite, with the presence of variscite and anatase like witnesses of this event in which, martite was crystalized to hematite.
文摘Most of the hinterland of the North China platform is devoid of Late Ordovician strata. The BaiyanhuaMountain section at Shetai Town is a standard section of the Upper Ordovician newly established in recentyears at the northernmost margin of the platform. This establishment directly involved the determination of thenorth boundary of the platform and the understanding of its evolutionary Listory. The area is quite differentfrom the binterland of the platform in Middle Ordovician rock types and sedimentary environments, with theformer characterized by frequent slope deposits and the latter consisting almost entirely of platform deposits.The present paper focuses on the petrographic features and sedimentary ervironments of the Middle-UpperOrdovician strata in the area, providing further theoretical support to the establishment of the section and fil-ling the gap in this respect.
