Durable aggregates are essential for the stability and longevity of construction projects,and the Los Angeles Abrasion(LAA)value is a widely used indicator of aggregate durability.However,direct LAA testing is time-co...Durable aggregates are essential for the stability and longevity of construction projects,and the Los Angeles Abrasion(LAA)value is a widely used indicator of aggregate durability.However,direct LAA testing is time-consuming,costly,and requires specialized facilities.This study introduces a novel and efficient alternative by developing two hybrid machine learning models Artificial Neural Network integrated with Particle Swarm Optimization(ANN-PSO)and Artificial Neural Network combined with Teaching-Learning-Based Optimization(ANN-TLBO)for the first time to predict LAA values from petrographic characteristics of carbonate rocks.A total of 160 rock samples from 10 geological formations in Pakistan’s Salt Range were analyzed through petrographic examination and LAA testing.The predictive performance of the proposed models was compared with established techniques,including Multiple Linear Regression,Random Forest,Adaptive Boosting,Gradient Boosting,K-Nearest Neighbors,and Multilayer Perceptron.Results demonstrate that ANN-PSO significantly outperformed all other approaches,achieving an R^(2)of 0.9982,RMSE of 0.209,MAE of 0.159,and MAPE of 0.009.Model robustness was validated using Taylor plots,REC curves,and an external dataset.Sensitivity analysis identified quartz,calcite,and feldspar as the most influential factors affecting LAA prediction.The findings confirm that the ANN-PSO and ANN-TLBO models provide highly accurate,cost-effective,and practical alternatives to traditional LAA testing.This innovative approach advances rock mechanics and material assessment,offering engineers and geologists enhanced tools for aggregate selection and durability evaluation in infrastructure projects.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
Petrographic, physical, and mechanical assessment investigation of NikanaiGhar limestone aggregate exposed in the Lower Dir area of Malakand Division, Pakistan, were conducted to evaluate and investigate its potential...Petrographic, physical, and mechanical assessment investigation of NikanaiGhar limestone aggregate exposed in the Lower Dir area of Malakand Division, Pakistan, were conducted to evaluate and investigate its potential for use as a construction material for engineering projects. Different geotechnical tests and petrographic analyses were performed to evaluate its potential for construction purposes. Geotechnical tests include unconfined compressive strength, ultimate tensile strength test, specific gravity, share strength, porosity, and water absorption. The evaluated physical attributes were compared to standard specifications to determine their suitability as a construction material. Petrographic investigation indicates mainly two types of stones. Stylolitic spar stone and Spar stone are metamorphosed equivalent limestones and are not prone to alkali-silica reactivity. Mutual relationships between physical parameters have been described by simple regression analysis. Significant direct correlation of specific gravity with ultimate tensile strength and uniaxial compressive strength was noted. However, negative trends of Porosity with ultimate tensile strength and uniaxial compressive strength were observed which is in accordance with standard. The analysis revealed that the limestones of NikanaiGhar Formation fall within the standard specification limits and can be used as aggregates for the indigenous construction industry.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
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
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
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
The Bethampudi layered anorthosite complex at the border zone of Archaean supracrustal rocks of Khammam district, Eastern Ghats shows normal stratification predominantly in the form of rhythmic layering and often exhi...The Bethampudi layered anorthosite complex at the border zone of Archaean supracrustal rocks of Khammam district, Eastern Ghats shows normal stratification predominantly in the form of rhythmic layering and often exhibits of zebra layering. Graded bedding and cumulate structures are also noticed. The rocks of the study area are classified based on petrography into anorthositic rocks, gabbroic rocks and ultramafic rocks and amphibolites. The field relations and major element composition suggest that these anorthosite rocks are of calc-alkaline in nature and petrogenitically related to the gabbroic rocks by the fractional crystallization at ℃.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
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
The characterization of carbonated rocks of Mintom allowed identifying three features (massive limestone, banded limestone and dolomite). Samples taken in these features were subjected to the physico-chemical analyses...The characterization of carbonated rocks of Mintom allowed identifying three features (massive limestone, banded limestone and dolomite). Samples taken in these features were subjected to the physico-chemical analyses and to the mechanical tests. The results obtained show a convergence in the mineralogical composition in particular in the calcareous features (smectite, micas and calcite);the dolomite feature being mainly constituted by dolomite associated with the smectite. The chemical composition allows finding contents raised in CaO, in all the samples. However, in the dolomite and the banded limestone, the concentrations in MgO and in SiO<sub>2</sub> are also important. The mechanical properties showed a good compression resistance for the massive limestone and the dolomite, the mechanical behavior of the banded limestone being low. The exploitation of these results allows recommending carbonated rocks of Mintom in the production of the clinker, agricultural amendments and in the constructions of the civil engineering.展开更多
The geology of the Zango-Daji area was investigated petrographically and geochemically to determine the study area’s rock types and mineralization potential.The study area is underlain by rocks of the basement comple...The geology of the Zango-Daji area was investigated petrographically and geochemically to determine the study area’s rock types and mineralization potential.The study area is underlain by rocks of the basement complex characterized by hilly and undulating rocks,which include granitic gneiss,migmatite gneiss,biotite hornblende granite gneiss,and pegmatites.Observation from the field shows that the study area is dominantly underlain by granitic gneiss.The granitic gneiss is dark grey,medium-coarse-grained,and characterized by weak foliation defined by the alignment of a streak of light and dark coloured minerals.They are widespread in the area constituting about 70%of rock types found in the study area.The average modal percentage of minerals in the rocks from petrographic studies shows that granitic gneiss had quartz 45%,plagioclase 10%,microcline 20%,hornblende 2%,biotite 10%,muscovite 5%,kyanite 8%and other minerals 5%.Also,the pegmatite of the study area has no evidence of mineralization;it contains minerals like quartz,feldspars(microcline and orthoclase),and micas(mostly muscovite).Geochemical analysis of the granitic gneiss of the study area shows that silica is by far the most abundant with a value of 53.5%,Na_(2)O value of 32.5%,Al_(2)O_(3),and k_(2)O of 6.1%and 4.0%,respectively.CaO value of 2.630%accounts for plagioclase feldspar in the granitic gneiss.The QAP diagram was used to determine the petrogenesis of the granitic gneiss.The plot shows the parent rock was a monzogranite with a low percentage of plagioclase in a thin section with a high percentage of quartz and alkali feldspar.The pegmatites of the study area are barren,as confirmed by the XRD result.展开更多
This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron mi...This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron microscopy,high-pressure mercury intrusion,and petrophysical testing to systematically evaluate reservoir petrographic features and pore structures.Results reveal that Benxi Formation sandstones predominantly comprise quartz sandstones,lithic quartz sandstones,and lithic sandstones,characterized by high quartz content,widespread volcanic lithic fragments,moderately well-sorted grains,and complex cement types.Pore types are dominated by residual intergranular and dissolution pores,with minor intracrystalline pores and fractures;overall porosity ranges from 0.17%to 9.07%(average 4.74%),and permeability from 0.01 to 6.05 mD,classifying them as ultra-low porosity and tight reservoirs.High-pressure mercury intrusion indicates microfine throats as the primary structure,divisible into four distinct types.Diagenetically,compaction and cementation are the main drivers of primary pore loss and reservoir tightening,whereas late-stage dissolution partially ameliorates pore networks.Overall,Benxi Formation sandstone reservoirs exhibit pervasive densification but localized favorable pore assemblages and connectivity,facilitating hydrocarbon migration and accumulation.These findings advance understanding of Upper Paleozoic tight sandstone reservoir characteristics and aid in predicting sweet spots.展开更多
The sand intervals of the Early Cretaceous Lower Goru Formation are a conventional reservoir,generally distributed in the Middle and Lower Indus Basin of Pakistan.Lithostratigraphically formation is classified into tw...The sand intervals of the Early Cretaceous Lower Goru Formation are a conventional reservoir,generally distributed in the Middle and Lower Indus Basin of Pakistan.Lithostratigraphically formation is classified into two parts;the upper parts are predominantly composed of shale,siltstone,and thin layers of alternate shale and sandstone,while the lower parts are composed of sandstone with interlayering of shale and limestone.The sandstone of the Lower Goru Formation has been further divided into A,B,C,and D sand intervals based on reservoir quality.Detailed depositional facies and reservoir characteristics are essential for the evaluation of hydrocarbon exploration and development.This paper aims to evaluate the depositional environment and reservoir characterization of the siliciclastic reservoir of the Early Cretaceous Lower Goru Formation by integrating the gamma-ray log patterns and petrographic analysis and scanning electron microscopic(SEM)analysis.Petrographic characterization of the sand intervals and Gamma-ray log signatures were used for the interpretation of the depositional environment of the reservoir intervals.Petrographic analysis reveals that the sandstone of the Lower Goru Formation is fine-to medium-grained,well-sorted,arkose or feldspathic arenite.Primary intergranular macroporosity,secondary intragranular macropores,and Intercrystalline micropores were identified within the sandstone by the SEM analysis.The diagenetic analysis suggests that the sandstone possesses high porosity,low permeability,and has undergone significant alterations such as compaction,quartz cementation,feldspar dissolution,and clay minerals alteration.Five electrofacies are interpreted based on gamma-ray log patterns including(1)funnel shape(FA);(2)bell shape(FB);(3)cylindrical shape(FC);(4)bow shape(FD);and(5)serrated shape(FE)patterns.The interpreted facies results reveal shoreface environment for A-sand,Tidal flat for B-sand,mixed tidal flat for C sand,Tide dominated mixed for D-sand,and transgressive shelf for Esand.The present study will be helpful for the assessment of the reservoir quality of the Early Cretaceous Lower Goru Formation for further exploration and development in the Indus Basin of Pakistan.展开更多
文摘Durable aggregates are essential for the stability and longevity of construction projects,and the Los Angeles Abrasion(LAA)value is a widely used indicator of aggregate durability.However,direct LAA testing is time-consuming,costly,and requires specialized facilities.This study introduces a novel and efficient alternative by developing two hybrid machine learning models Artificial Neural Network integrated with Particle Swarm Optimization(ANN-PSO)and Artificial Neural Network combined with Teaching-Learning-Based Optimization(ANN-TLBO)for the first time to predict LAA values from petrographic characteristics of carbonate rocks.A total of 160 rock samples from 10 geological formations in Pakistan’s Salt Range were analyzed through petrographic examination and LAA testing.The predictive performance of the proposed models was compared with established techniques,including Multiple Linear Regression,Random Forest,Adaptive Boosting,Gradient Boosting,K-Nearest Neighbors,and Multilayer Perceptron.Results demonstrate that ANN-PSO significantly outperformed all other approaches,achieving an R^(2)of 0.9982,RMSE of 0.209,MAE of 0.159,and MAPE of 0.009.Model robustness was validated using Taylor plots,REC curves,and an external dataset.Sensitivity analysis identified quartz,calcite,and feldspar as the most influential factors affecting LAA prediction.The findings confirm that the ANN-PSO and ANN-TLBO models provide highly accurate,cost-effective,and practical alternatives to traditional LAA testing.This innovative approach advances rock mechanics and material assessment,offering engineers and geologists enhanced tools for aggregate selection and durability evaluation in infrastructure projects.
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.
文摘Petrographic, physical, and mechanical assessment investigation of NikanaiGhar limestone aggregate exposed in the Lower Dir area of Malakand Division, Pakistan, were conducted to evaluate and investigate its potential for use as a construction material for engineering projects. Different geotechnical tests and petrographic analyses were performed to evaluate its potential for construction purposes. Geotechnical tests include unconfined compressive strength, ultimate tensile strength test, specific gravity, share strength, porosity, and water absorption. The evaluated physical attributes were compared to standard specifications to determine their suitability as a construction material. Petrographic investigation indicates mainly two types of stones. Stylolitic spar stone and Spar stone are metamorphosed equivalent limestones and are not prone to alkali-silica reactivity. Mutual relationships between physical parameters have been described by simple regression analysis. Significant direct correlation of specific gravity with ultimate tensile strength and uniaxial compressive strength was noted. However, negative trends of Porosity with ultimate tensile strength and uniaxial compressive strength were observed which is in accordance with standard. The analysis revealed that the limestones of NikanaiGhar Formation fall within the standard specification limits and can be used as aggregates for the indigenous construction industry.
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.
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.
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The Bethampudi layered anorthosite complex at the border zone of Archaean supracrustal rocks of Khammam district, Eastern Ghats shows normal stratification predominantly in the form of rhythmic layering and often exhibits of zebra layering. Graded bedding and cumulate structures are also noticed. The rocks of the study area are classified based on petrography into anorthositic rocks, gabbroic rocks and ultramafic rocks and amphibolites. The field relations and major element composition suggest that these anorthosite rocks are of calc-alkaline in nature and petrogenitically related to the gabbroic rocks by the fractional crystallization at ℃.
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.
文摘The characterization of carbonated rocks of Mintom allowed identifying three features (massive limestone, banded limestone and dolomite). Samples taken in these features were subjected to the physico-chemical analyses and to the mechanical tests. The results obtained show a convergence in the mineralogical composition in particular in the calcareous features (smectite, micas and calcite);the dolomite feature being mainly constituted by dolomite associated with the smectite. The chemical composition allows finding contents raised in CaO, in all the samples. However, in the dolomite and the banded limestone, the concentrations in MgO and in SiO<sub>2</sub> are also important. The mechanical properties showed a good compression resistance for the massive limestone and the dolomite, the mechanical behavior of the banded limestone being low. The exploitation of these results allows recommending carbonated rocks of Mintom in the production of the clinker, agricultural amendments and in the constructions of the civil engineering.
文摘The geology of the Zango-Daji area was investigated petrographically and geochemically to determine the study area’s rock types and mineralization potential.The study area is underlain by rocks of the basement complex characterized by hilly and undulating rocks,which include granitic gneiss,migmatite gneiss,biotite hornblende granite gneiss,and pegmatites.Observation from the field shows that the study area is dominantly underlain by granitic gneiss.The granitic gneiss is dark grey,medium-coarse-grained,and characterized by weak foliation defined by the alignment of a streak of light and dark coloured minerals.They are widespread in the area constituting about 70%of rock types found in the study area.The average modal percentage of minerals in the rocks from petrographic studies shows that granitic gneiss had quartz 45%,plagioclase 10%,microcline 20%,hornblende 2%,biotite 10%,muscovite 5%,kyanite 8%and other minerals 5%.Also,the pegmatite of the study area has no evidence of mineralization;it contains minerals like quartz,feldspars(microcline and orthoclase),and micas(mostly muscovite).Geochemical analysis of the granitic gneiss of the study area shows that silica is by far the most abundant with a value of 53.5%,Na_(2)O value of 32.5%,Al_(2)O_(3),and k_(2)O of 6.1%and 4.0%,respectively.CaO value of 2.630%accounts for plagioclase feldspar in the granitic gneiss.The QAP diagram was used to determine the petrogenesis of the granitic gneiss.The plot shows the parent rock was a monzogranite with a low percentage of plagioclase in a thin section with a high percentage of quartz and alkali feldspar.The pegmatites of the study area are barren,as confirmed by the XRD result.
文摘This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron microscopy,high-pressure mercury intrusion,and petrophysical testing to systematically evaluate reservoir petrographic features and pore structures.Results reveal that Benxi Formation sandstones predominantly comprise quartz sandstones,lithic quartz sandstones,and lithic sandstones,characterized by high quartz content,widespread volcanic lithic fragments,moderately well-sorted grains,and complex cement types.Pore types are dominated by residual intergranular and dissolution pores,with minor intracrystalline pores and fractures;overall porosity ranges from 0.17%to 9.07%(average 4.74%),and permeability from 0.01 to 6.05 mD,classifying them as ultra-low porosity and tight reservoirs.High-pressure mercury intrusion indicates microfine throats as the primary structure,divisible into four distinct types.Diagenetically,compaction and cementation are the main drivers of primary pore loss and reservoir tightening,whereas late-stage dissolution partially ameliorates pore networks.Overall,Benxi Formation sandstone reservoirs exhibit pervasive densification but localized favorable pore assemblages and connectivity,facilitating hydrocarbon migration and accumulation.These findings advance understanding of Upper Paleozoic tight sandstone reservoir characteristics and aid in predicting sweet spots.
基金the National Natural Science Foundation of China(grant No:41390451).
文摘The sand intervals of the Early Cretaceous Lower Goru Formation are a conventional reservoir,generally distributed in the Middle and Lower Indus Basin of Pakistan.Lithostratigraphically formation is classified into two parts;the upper parts are predominantly composed of shale,siltstone,and thin layers of alternate shale and sandstone,while the lower parts are composed of sandstone with interlayering of shale and limestone.The sandstone of the Lower Goru Formation has been further divided into A,B,C,and D sand intervals based on reservoir quality.Detailed depositional facies and reservoir characteristics are essential for the evaluation of hydrocarbon exploration and development.This paper aims to evaluate the depositional environment and reservoir characterization of the siliciclastic reservoir of the Early Cretaceous Lower Goru Formation by integrating the gamma-ray log patterns and petrographic analysis and scanning electron microscopic(SEM)analysis.Petrographic characterization of the sand intervals and Gamma-ray log signatures were used for the interpretation of the depositional environment of the reservoir intervals.Petrographic analysis reveals that the sandstone of the Lower Goru Formation is fine-to medium-grained,well-sorted,arkose or feldspathic arenite.Primary intergranular macroporosity,secondary intragranular macropores,and Intercrystalline micropores were identified within the sandstone by the SEM analysis.The diagenetic analysis suggests that the sandstone possesses high porosity,low permeability,and has undergone significant alterations such as compaction,quartz cementation,feldspar dissolution,and clay minerals alteration.Five electrofacies are interpreted based on gamma-ray log patterns including(1)funnel shape(FA);(2)bell shape(FB);(3)cylindrical shape(FC);(4)bow shape(FD);and(5)serrated shape(FE)patterns.The interpreted facies results reveal shoreface environment for A-sand,Tidal flat for B-sand,mixed tidal flat for C sand,Tide dominated mixed for D-sand,and transgressive shelf for Esand.The present study will be helpful for the assessment of the reservoir quality of the Early Cretaceous Lower Goru Formation for further exploration and development in the Indus Basin of Pakistan.
