The Eastern Desert of Egypt suffered a protracted period of deformation triggered by cratonization of the new juvenile crust known as the Arabian Nubian Shield(ANS),which has been proposed for potential gold discoveri...The Eastern Desert of Egypt suffered a protracted period of deformation triggered by cratonization of the new juvenile crust known as the Arabian Nubian Shield(ANS),which has been proposed for potential gold discoveries associated with the corresponding tectonic event.The Fatira area,on the border of Egypt’s Northern and Central Eastern Deserts,is covered with metavolcanic rocks twisted by a dextral relocation of the Fatira Shear Zone(FSZ)relative to the Barud magmatic body.The recent study evaluated many deformed post-orogenic granitic intrusions and felsite dikes associated with promising mineralization localities,notably orogenic gold deposits.The combination of various field observations and remote sensing data,followed by the analysis of aeromagnetic enhanced maps,allowed the differentiation of distinct lithologies,structural features,and hydrothermal alterations in the study area.Additionally,the integrated results obtained from the different interpretation techniques are utilized to identify and confirm the previously supposed mineralized localities in the Fatira and Abu Zawal areas and predict other matched localities.The final ASTER,Sentinel 2 hydrothermal alteration,and orientation entropy heat maps demonstrate the association between these mineralized regions and major structures related to the FSZ late stage of deformation rather than other structures studied throughout the area of interest.展开更多
The Damoshan deposit is a small B-F-Sn Bi exoskarn deposit and contains a distinctive mineral assemblage comprising andradite,vesuvianite,calcite,diopside,magnetite,hematite,nordenskioldine,cassiterite,varlamoffite,sc...The Damoshan deposit is a small B-F-Sn Bi exoskarn deposit and contains a distinctive mineral assemblage comprising andradite,vesuvianite,calcite,diopside,magnetite,hematite,nordenskioldine,cassiterite,varlamoffite,schenfliesite,native bismuth,eulytite,bismite and bismuthite,in which the occurrence of eulytite is the first reported in China.Textures of the mineral paragenses show that andradite,vesuvianite and diopside were the earliest phases formed during metasomatism,i.e.,the skarn forming stage.Then nordenskioldine,magnetite and native bismuth,perhaps together with eulytite,were precipitated at the stage of retrograde alteration.The minerals varlamoffite,schoenfliesite,hematite ,bismite and bismuthite were probably the product of supergene alteration.The minerals were analyzed by means of electron microprobe.The data on the ,coexisting phases and their compositons show that during the metasomatism reduced F-and Sn-rich primary mineralizing solutions reacted with highly oxidized carbonated of the Gejie Formation,producing a high Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(andradite skarn)in the outer zone of the skarn body in which andradite is extremely tin-bearing up to 5.14 wt% SnO2),In the retrograde alteration stage ,B-rich,but F-and Si-deficient mineralizing solutions replaced the tin-bearing andradite,forming an association of nordenskioldine and magnetite,No sulphides were deposited at this stage because of the oxidization ambient conditions in the andradite skarn.In the spergene oxidation zone,the nordenskioldine was dissolved into varlmoffite and calcite,the native bismuth was transformed into bismite or bismuthite ,and the magnetite was altered into hematite under the action of the CO2-rich supergene solutions.展开更多
As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hoste...As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hosted in aeschynite-(Ce) and(Nd),but with subsidiary amounts of pyrochlore,fergusonite-(Ce),fersmite and columbite.Here we report on the paragenetic and textural setting of aeschynite,pyrochlore and fergusonite in the main ore bodies and in a carbonatite dyke.Niobium in a carbonatite sample is hosted in a phase tentatively(due to significant Ca,Mn and Ti contents) identified as fergusonite-(Ce).Aeschynite occurs overgrowing foliation in banded ores,in fractures and vugs in aegirine-rich rocks and in calcite veins.The composition in all settings is similar,but some examples in banded ores develop significant zonation in Y,Th and the REE,inferred to relate to buffering of halogen acid species to low levels by dissolution and fluoritisation of calcite,and the preferential precipitation of LREE from solution due to lower mineral solubility products compared to the HREE.Although lower in total concentration the ratios of REE in pyrochlore are similar to those of aeschynite and suggest the same metal source.The crystallisation of pyrochlore probably relates to growth in paragenetic settings where carbonates had already been eliminated and hence the buffering of F-species activities in the hydrothermal fluid was reduced.Both aeschynite and pyrochlore show evidence of alteration.Primary alteration of aeschynite resulted in leaching of A-site cations(Ca,REE,Th) and Nb,addition of Fe,and ultimately replacement by Ba-Ti phases(baotite and bafertisite).Secondary,metamictisation enhanced,possibly supergene alteration of pyrochlore resulted in hydration,leaching of A-site cations leading to the development of lattice vacancies and increases in Si.The presence of hydrothermal Nb resources at Bayan Obo suggests there may be potential for further Nb discoveries in the area,whilst the trends in element mobility during alteration have significant implications for the utility of A-B oxides as components of materials for immobilisation of radionuclides.展开更多
The capabilities and opportunities of the application of automated mineralogy for the characterization of lithium-bearing zinnwaldite-micas are critically assessed. Samples of a crushed greisen-type ore comprising mos...The capabilities and opportunities of the application of automated mineralogy for the characterization of lithium-bearing zinnwaldite-micas are critically assessed. Samples of a crushed greisen-type ore comprising mostly of quartz, topaz and zinnwaldite (Li-rich mica) were exposed to further comminution by cone crusher and high voltage pulse power fragmentation. Product properties were analyzed by using a Mineral Liberation Analyser (MLA) and the obtained mineralogical and mineral processing relevant parameters were carefully evaluated with special focus on the characteristics of zinnwaldite. The results illustrate that both samples contain a significant quantity of very fine particles that are products of comminution. The modal mineralogy in the different sieve fractions is characterized by the accumulation of minerals of low hardness in the finest fraction and the enrichment of topaz, having a high hardness, in the somewhat larger fractions. Based on the results of mineral association data for zinnwaldite, a displacement of the muscovite-quartz ratio, in comparison to the results of modal mineralogy, was observed by indicating good quartz-zinnwaldite boundary breakage and weak muscovite-zinnwaldite breakage. Liberation as well as mineral grade recovery curves indicate that fraction 1000 to +500 μm is most suitable for beneficiation. The results of this study demonstrate that SEM-based image analysis, such as MLA, can effectively be used to investigate and evaluate phyllosilicate minerals in a fast and precise way. It is shown that the results of MLA investigations, such as modal mineralogy, are in good agreement with other analytical methods such as quantitative X-ray powder diffraction.展开更多
In the early 1990 s, the Foundation for Science and Technology of Rio Grande do Sul State(CIENTEC)developed a pioneering study in Brazil, related to the simultaneous mining of multiple coal seams.One of the activities...In the early 1990 s, the Foundation for Science and Technology of Rio Grande do Sul State(CIENTEC)developed a pioneering study in Brazil, related to the simultaneous mining of multiple coal seams.One of the activities included detailed studies on the geomechanical characterization of materials present in the Irapua coal seam, under exploitation in the A-Sangao Mine, located near the city of Criciuma-SC,within the South-Catarinense coalfield. The goal of the laboratory tests was to define the behavior of the uniaxial compressive strength of the Irapua coal seam and establish a first approximation for the in situ strength value of this coal seam, since existing knowledge is solely based on practical mining experience over the years. Large samples of the coal seam were collected, using special techniques to maintain the integrity of the material, and a set of 56 uniaxial compression tests in cubic specimens, with side length ranging from 4.5 to 31 cm, were conducted in laboratory. This paper describes the experimental techniques used in the assays, and also presents the uniaxial compression strength results obtained.Moreover, important aspects of this type of study are considered, highlighting the size effect for the carbonaceous bed and the estimation of in situ strength values for the Irapua coal seam.展开更多
The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It...The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) A; b=12.3109(2) A; c=3.03712 (7) A; and V=345.91(1) A3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-AI3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.4sFe2+o.46Fe3+o.osMno.o2)2.o1 (Fe3+o.94Fe2+0.04Al0.02)1.00B1.00Os composition. The formation temperature was estimated to be about 500- 600C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.展开更多
Dating of fracture-filling calcitewith U-Pb geochronology is becoming a rapidly adopted technique for determining the absolute timing of brittle deformation in the upper crust.Slickenfibre calcite is a desirable targe...Dating of fracture-filling calcitewith U-Pb geochronology is becoming a rapidly adopted technique for determining the absolute timing of brittle deformation in the upper crust.Slickenfibre calcite is a desirable target,as it precipitates between individual fault slip displacement events,and provides additional kinematic information.Here we present a case study of slickenfibres formed on the Očkov thrust in the Lower Palaezoic Prague Basin,Bohemian Massif,utilising a combination of petrographic and in situ methods.We demonstrate that slickenfibre external textures can be preserved,whilst internally primary textures are removed by fluid infiltration and recrystallization,leading to variable U and Pb mobilisation.One slickenfibre yielded a date of ca.250 Ma,which we interpret as recording fault slip along the Očkov thrust.Another cross-cutting slickenfibre yielded more scattered U-Pb data,with an imprecise apparent age around ca.95 Ma.This slickenfibre is recrystallised,destroying the primary textures,and exhibits element mobility.The meaning of this younger apparent age is therefore questionable;whereas it likely reflects Cretaceous U and Pb mobility assisted by fluid-flow along the fault plane,it may not reflect a period of fault slip.Our results demonstrate that slickenfibre-based U-Pb dates do not unequivocally relate to fault motion,and that petrographic and elemental analyses are important requirements for interpreting calcite U-Pb data.展开更多
Carbon capture and storage(CCS)has been proposed as a potential technology to mitigate climate change.However,there is currently a huge gap between the current global deployment of this technology and that which will ...Carbon capture and storage(CCS)has been proposed as a potential technology to mitigate climate change.However,there is currently a huge gap between the current global deployment of this technology and that which will be ultimately required.Whilst CO2 can be captured at any geographic location,storage of CO2 will be constrained by the geological storage potential in the area the CO2 is captured.The geological storage potential can be evaluated at a very high level according to the tectonic setting of the target area.To date,CCS deployment has been restricted to more favourable tectonic settings,such as extensional passive margin and post-rift basins and compressional foreland basins.However,to reach the adequate level of deployment,the potential for CCS of regions in different tectonic settings needs to be explored and assessed worldwide.Surprisingly,the potential of compressional basins for carbon storage has not been universally evaluated according to the global and regional carbon emission distribution.Here,we present an integrated source-to-sink analysis tool that combines comprehensive,open-access information on basin distribution,hydrocarbon resources and CO2 emissions based on geographical information systems(GIS).Compressional settings host some of the most significant hydrocarbon-bearing basins and 36% of inland CO2 emissions but,to date,large-scale CCS facilities in compressional basins are concentrated in North America and the Middle East only.Our source-to-sink tool allows identifying five high-priority regions for prospective CCS development in compressional basins:North America,north-western South America,south-eastern Europe,the western Middle East and western China.We present a study of the characteristics of these areas in terms of CO2 emissions and CO2 storage potential.Additionally,we conduct a detailed case-study analysis of the Sichuan Basin(China),one of the compressional basins with the greatest CO2 storage potential.Our results indicate that compressional basins will have to play a critical role in the future of CCS if this technology is to be implemented worldwide.展开更多
This study focuses on the geochemistry of trace elements and parameters of coal quality of bituminous coal belonging to the upper Triassic-lower Jurassic era, collected from the Galandrud region in Central Alborz, nor...This study focuses on the geochemistry of trace elements and parameters of coal quality of bituminous coal belonging to the upper Triassic-lower Jurassic era, collected from the Galandrud region in Central Alborz, northern Iran. Galandrud coal on an air-dried basis are characterized by broad variation in the amount of ash (ranging from 6.49g to 12.73%), a high content of volatile matter (33,32-37.45%) and high gross calorific values (7430-8880 kcal/kg). The mineral matter of the coal samples studied is made up of dolomite (〉909g), quartz, sphalerite, galena, pyrite and clay minerals. Major elements are positively cor- related with ash content suggesting an association with inorganic constituents. Based on statistical anal- yses, concentrations of trace elements such as Co (51.3 ×10^-6-152.9× 10^-6), Ba (368× 10^-6-3297.4×10^-6), Cr (65.5 ×10^-6-194.2 × 10^-6), Mo (5.6 × 10^-6-18.2× 10^-6), Hi (72.9 × 10^-6-152.9 × 10^-6) and V (245.5 × 10^-6-520 ×10^-6) are higher than world coal averages. However, low concentration of some vol- atile elements such as As, Hg and U are present in low concentrations of the various types of coal studied.展开更多
Various metacarbonate and associated calc-silicate rocks form minor but genetically significant components of the lithological units in the Bohemian Massif of the Variscan orogen in Central Europe.These rocks vary in ...Various metacarbonate and associated calc-silicate rocks form minor but genetically significant components of the lithological units in the Bohemian Massif of the Variscan orogen in Central Europe.These rocks vary in terms of their lithostratigraphy,chemical composition and mineral assemblage(dolomite/calcite ratio,silicate abundance).Tourmaline is present in five paragenetic settings within the metacarbonate and calc-silicate units.TypeⅠcomprises individual,euhedral,prismatic grains and grain aggregates in a carbonate-dominant(calcite±dolomite)matrix poor in silicates.TypeⅡis characterized by euhedral to subhedral grains and coarse-to fine-grained aggregates in silicate-rich layers/nests within metacarbonate bodies whereas typeⅢoccurs as prismatic grains and aggregates at the contact zones between carbonate and associated silicate host rocks.TypeⅣis in veins crosscutting metacarbonate bodies,and typeⅣtourmaline occurs at the exocontacts of elbaite-subtype granitic pegmatite.Tourmaline from the different settings shows distinctive compositional features.Typical for typeⅠare Mg-rich compositions,with fluor-uvite>dravite>>magnesio-lucchesiite.Tourmalines from typeⅡsilicate-rich layers/nests are highly variable,corresponding to oxy-schorl,magnesio-foitite,Al-rich dravite and fluor-uvite.Typical for typeⅢtourmalines are Ca,Ti-bearing oxy-dravite compositions.The typeⅣveins feature dravite and fluor-uvite tourmaline compositions whereas typeⅤtourmaline is Li,F-rich dravite.Tourmaline is the only Bbearing phase in paragenetic typesⅠ-Ⅳ,where it is characterised by two principal ranges of B-isotope composition(δ^11B=-13‰to-9‰and-18‰to-14‰).These ranges correspond to regionally different units of the Moldanubian Zone.Thus,the Svratka Unit(Moldanubian Zone s.l.)contains only isotopically lighter tourmaline(δ^11B=-18‰to-14‰),whereas metacarbonates in the Poli?ka unit(Teplá-Barrandian Zone)and Olesnice unit(Moravicum of the Moravo-Silesian Zone)has exclusively isotopically heavier tourmaline(δ^11B=-9‰to-13‰).Tourmalines from metacarbonates in the Variegated Unit cover both ranges of isotope composition.The isotopically light end of the B isotope range may indicate the presence of continental evaporites within individual investigated areas.On the other hand,variations in the range of~8δ-units is consistent with the reported shift in B isotopic composition of metasedimentary rocks of the Bohemian Massif due to the prograde metamorphism from very-low grade to eclogite facies.In contrast to the metacarbonate-hosted settings,tourmaline of paragenetic type V from the exocontact of granitic pegmatites displays a significantly heavier range ofδ^11B(as low as-7.7‰to-0.6‰),which is attributed to partitioning of 10 B to cogenetic axinite and/or different B-signature of the source pegmatite containing tourmaline with heavyδ^11B signature.展开更多
Numerous investigations on submarine hydrothermal ore-forming occurrence have been actively carried out in the last two decades with significant results.The Ag and Au enrichments in the sulfides from black smokers ofh...Numerous investigations on submarine hydrothermal ore-forming occurrence have been actively carried out in the last two decades with significant results.The Ag and Au enrichments in the sulfides from black smokers ofhydrothermal vent field Broken Spur(MAR) aroused our interest to study their mineral hosting forms.Samples were collected from seven hydrothermal chimneys within Broken Spur in the British-Russian BRAVEX(1994) and展开更多
In the last couple of years the Museum developed a project financed by the National Agency for Culture and Technology in partnership with four schools from Lisbon.The guidelines of this project were the climate change...In the last couple of years the Museum developed a project financed by the National Agency for Culture and Technology in partnership with four schools from Lisbon.The guidelines of this project were the climate change and its influence on human lives in our society and on other living beings."Changing climate, changing lives",our project,evolved 8 months work of about 150 high school grade students,in which展开更多
基金The Egyptian ministry for higher educationthe Stipendium Hungaricum scholarship are thanked for funding the first and third authors under the joint executive program between Hungary and Egypt。
文摘The Eastern Desert of Egypt suffered a protracted period of deformation triggered by cratonization of the new juvenile crust known as the Arabian Nubian Shield(ANS),which has been proposed for potential gold discoveries associated with the corresponding tectonic event.The Fatira area,on the border of Egypt’s Northern and Central Eastern Deserts,is covered with metavolcanic rocks twisted by a dextral relocation of the Fatira Shear Zone(FSZ)relative to the Barud magmatic body.The recent study evaluated many deformed post-orogenic granitic intrusions and felsite dikes associated with promising mineralization localities,notably orogenic gold deposits.The combination of various field observations and remote sensing data,followed by the analysis of aeromagnetic enhanced maps,allowed the differentiation of distinct lithologies,structural features,and hydrothermal alterations in the study area.Additionally,the integrated results obtained from the different interpretation techniques are utilized to identify and confirm the previously supposed mineralized localities in the Fatira and Abu Zawal areas and predict other matched localities.The final ASTER,Sentinel 2 hydrothermal alteration,and orientation entropy heat maps demonstrate the association between these mineralized regions and major structures related to the FSZ late stage of deformation rather than other structures studied throughout the area of interest.
文摘The Damoshan deposit is a small B-F-Sn Bi exoskarn deposit and contains a distinctive mineral assemblage comprising andradite,vesuvianite,calcite,diopside,magnetite,hematite,nordenskioldine,cassiterite,varlamoffite,schenfliesite,native bismuth,eulytite,bismite and bismuthite,in which the occurrence of eulytite is the first reported in China.Textures of the mineral paragenses show that andradite,vesuvianite and diopside were the earliest phases formed during metasomatism,i.e.,the skarn forming stage.Then nordenskioldine,magnetite and native bismuth,perhaps together with eulytite,were precipitated at the stage of retrograde alteration.The minerals varlamoffite,schoenfliesite,hematite ,bismite and bismuthite were probably the product of supergene alteration.The minerals were analyzed by means of electron microprobe.The data on the ,coexisting phases and their compositons show that during the metasomatism reduced F-and Sn-rich primary mineralizing solutions reacted with highly oxidized carbonated of the Gejie Formation,producing a high Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(vesuvianite-fluorite skarn)near the contact of granite,and a low Fe^2+/Fe^3+ skarn(andradite skarn)in the outer zone of the skarn body in which andradite is extremely tin-bearing up to 5.14 wt% SnO2),In the retrograde alteration stage ,B-rich,but F-and Si-deficient mineralizing solutions replaced the tin-bearing andradite,forming an association of nordenskioldine and magnetite,No sulphides were deposited at this stage because of the oxidization ambient conditions in the andradite skarn.In the spergene oxidation zone,the nordenskioldine was dissolved into varlmoffite and calcite,the native bismuth was transformed into bismite or bismuthite ,and the magnetite was altered into hematite under the action of the CO2-rich supergene solutions.
文摘As well as world class Fe and REE resources the Bayan Obo mineral deposits also hosts significant niobium resources(estimated as 2.2 Mt Nb with an average grade of 0.13 wt% Nb).Niobium in this study is primarily hosted in aeschynite-(Ce) and(Nd),but with subsidiary amounts of pyrochlore,fergusonite-(Ce),fersmite and columbite.Here we report on the paragenetic and textural setting of aeschynite,pyrochlore and fergusonite in the main ore bodies and in a carbonatite dyke.Niobium in a carbonatite sample is hosted in a phase tentatively(due to significant Ca,Mn and Ti contents) identified as fergusonite-(Ce).Aeschynite occurs overgrowing foliation in banded ores,in fractures and vugs in aegirine-rich rocks and in calcite veins.The composition in all settings is similar,but some examples in banded ores develop significant zonation in Y,Th and the REE,inferred to relate to buffering of halogen acid species to low levels by dissolution and fluoritisation of calcite,and the preferential precipitation of LREE from solution due to lower mineral solubility products compared to the HREE.Although lower in total concentration the ratios of REE in pyrochlore are similar to those of aeschynite and suggest the same metal source.The crystallisation of pyrochlore probably relates to growth in paragenetic settings where carbonates had already been eliminated and hence the buffering of F-species activities in the hydrothermal fluid was reduced.Both aeschynite and pyrochlore show evidence of alteration.Primary alteration of aeschynite resulted in leaching of A-site cations(Ca,REE,Th) and Nb,addition of Fe,and ultimately replacement by Ba-Ti phases(baotite and bafertisite).Secondary,metamictisation enhanced,possibly supergene alteration of pyrochlore resulted in hydration,leaching of A-site cations leading to the development of lattice vacancies and increases in Si.The presence of hydrothermal Nb resources at Bayan Obo suggests there may be potential for further Nb discoveries in the area,whilst the trends in element mobility during alteration have significant implications for the utility of A-B oxides as components of materials for immobilisation of radionuclides.
文摘The capabilities and opportunities of the application of automated mineralogy for the characterization of lithium-bearing zinnwaldite-micas are critically assessed. Samples of a crushed greisen-type ore comprising mostly of quartz, topaz and zinnwaldite (Li-rich mica) were exposed to further comminution by cone crusher and high voltage pulse power fragmentation. Product properties were analyzed by using a Mineral Liberation Analyser (MLA) and the obtained mineralogical and mineral processing relevant parameters were carefully evaluated with special focus on the characteristics of zinnwaldite. The results illustrate that both samples contain a significant quantity of very fine particles that are products of comminution. The modal mineralogy in the different sieve fractions is characterized by the accumulation of minerals of low hardness in the finest fraction and the enrichment of topaz, having a high hardness, in the somewhat larger fractions. Based on the results of mineral association data for zinnwaldite, a displacement of the muscovite-quartz ratio, in comparison to the results of modal mineralogy, was observed by indicating good quartz-zinnwaldite boundary breakage and weak muscovite-zinnwaldite breakage. Liberation as well as mineral grade recovery curves indicate that fraction 1000 to +500 μm is most suitable for beneficiation. The results of this study demonstrate that SEM-based image analysis, such as MLA, can effectively be used to investigate and evaluate phyllosilicate minerals in a fast and precise way. It is shown that the results of MLA investigations, such as modal mineralogy, are in good agreement with other analytical methods such as quantitative X-ray powder diffraction.
文摘In the early 1990 s, the Foundation for Science and Technology of Rio Grande do Sul State(CIENTEC)developed a pioneering study in Brazil, related to the simultaneous mining of multiple coal seams.One of the activities included detailed studies on the geomechanical characterization of materials present in the Irapua coal seam, under exploitation in the A-Sangao Mine, located near the city of Criciuma-SC,within the South-Catarinense coalfield. The goal of the laboratory tests was to define the behavior of the uniaxial compressive strength of the Irapua coal seam and establish a first approximation for the in situ strength value of this coal seam, since existing knowledge is solely based on practical mining experience over the years. Large samples of the coal seam were collected, using special techniques to maintain the integrity of the material, and a set of 56 uniaxial compression tests in cubic specimens, with side length ranging from 4.5 to 31 cm, were conducted in laboratory. This paper describes the experimental techniques used in the assays, and also presents the uniaxial compression strength results obtained.Moreover, important aspects of this type of study are considered, highlighting the size effect for the carbonaceous bed and the estimation of in situ strength values for the Irapua coal seam.
文摘The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) A; b=12.3109(2) A; c=3.03712 (7) A; and V=345.91(1) A3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-AI3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.4sFe2+o.46Fe3+o.osMno.o2)2.o1 (Fe3+o.94Fe2+0.04Al0.02)1.00B1.00Os composition. The formation temperature was estimated to be about 500- 600C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.
基金by the Czech Science Foundation through Grant No.16-11500S(to JiříŽák)by the Charles University through Centre for Geosphere Dynamics(UNCE/SCI/006)project PROGRES Q45.Wealso acknowledge financial support from theMinistry of Culture of the Czech Republic through project DKRVO 2019–2023/1.IV.b(National Museum,00023272).
文摘Dating of fracture-filling calcitewith U-Pb geochronology is becoming a rapidly adopted technique for determining the absolute timing of brittle deformation in the upper crust.Slickenfibre calcite is a desirable target,as it precipitates between individual fault slip displacement events,and provides additional kinematic information.Here we present a case study of slickenfibres formed on the Očkov thrust in the Lower Palaezoic Prague Basin,Bohemian Massif,utilising a combination of petrographic and in situ methods.We demonstrate that slickenfibre external textures can be preserved,whilst internally primary textures are removed by fluid infiltration and recrystallization,leading to variable U and Pb mobilisation.One slickenfibre yielded a date of ca.250 Ma,which we interpret as recording fault slip along the Očkov thrust.Another cross-cutting slickenfibre yielded more scattered U-Pb data,with an imprecise apparent age around ca.95 Ma.This slickenfibre is recrystallised,destroying the primary textures,and exhibits element mobility.The meaning of this younger apparent age is therefore questionable;whereas it likely reflects Cretaceous U and Pb mobility assisted by fluid-flow along the fault plane,it may not reflect a period of fault slip.Our results demonstrate that slickenfibre-based U-Pb dates do not unequivocally relate to fault motion,and that petrographic and elemental analyses are important requirements for interpreting calcite U-Pb data.
基金the framework of DGICYT Spanish Projects CGL2015-66335-C2-1-R and PGC2018-093903-B-C22Grup Consolidat de Recerca“Geologia Sedimentaria”(2017-SGR-824)+5 种基金funded by the China Scholarship Council(CSC)(201806450043)JA received funding by EIT Raw Materials–SIT4ME Project(17024)funded by MICINN(Juan de la Cierva fellowship-IJC2018-036074-I)funding by the AGAUR(Agencia de Gestio d’Ajuts Universitaris i de Recerca)of the Generalitat de Catalunya(“Beatriu de Pinos”fellowship 2017SGR-824)the Spanish Ministry of Science,Innovation and Universities(“Ramon y Cajal”fellowship RYC2018-026335-I)funded by the University of Strathclyde Faculty of Engineering。
文摘Carbon capture and storage(CCS)has been proposed as a potential technology to mitigate climate change.However,there is currently a huge gap between the current global deployment of this technology and that which will be ultimately required.Whilst CO2 can be captured at any geographic location,storage of CO2 will be constrained by the geological storage potential in the area the CO2 is captured.The geological storage potential can be evaluated at a very high level according to the tectonic setting of the target area.To date,CCS deployment has been restricted to more favourable tectonic settings,such as extensional passive margin and post-rift basins and compressional foreland basins.However,to reach the adequate level of deployment,the potential for CCS of regions in different tectonic settings needs to be explored and assessed worldwide.Surprisingly,the potential of compressional basins for carbon storage has not been universally evaluated according to the global and regional carbon emission distribution.Here,we present an integrated source-to-sink analysis tool that combines comprehensive,open-access information on basin distribution,hydrocarbon resources and CO2 emissions based on geographical information systems(GIS).Compressional settings host some of the most significant hydrocarbon-bearing basins and 36% of inland CO2 emissions but,to date,large-scale CCS facilities in compressional basins are concentrated in North America and the Middle East only.Our source-to-sink tool allows identifying five high-priority regions for prospective CCS development in compressional basins:North America,north-western South America,south-eastern Europe,the western Middle East and western China.We present a study of the characteristics of these areas in terms of CO2 emissions and CO2 storage potential.Additionally,we conduct a detailed case-study analysis of the Sichuan Basin(China),one of the compressional basins with the greatest CO2 storage potential.Our results indicate that compressional basins will have to play a critical role in the future of CCS if this technology is to be implemented worldwide.
基金supported by the Iranian Institute for Geological Surveys and Mineral Exploration
文摘This study focuses on the geochemistry of trace elements and parameters of coal quality of bituminous coal belonging to the upper Triassic-lower Jurassic era, collected from the Galandrud region in Central Alborz, northern Iran. Galandrud coal on an air-dried basis are characterized by broad variation in the amount of ash (ranging from 6.49g to 12.73%), a high content of volatile matter (33,32-37.45%) and high gross calorific values (7430-8880 kcal/kg). The mineral matter of the coal samples studied is made up of dolomite (〉909g), quartz, sphalerite, galena, pyrite and clay minerals. Major elements are positively cor- related with ash content suggesting an association with inorganic constituents. Based on statistical anal- yses, concentrations of trace elements such as Co (51.3 ×10^-6-152.9× 10^-6), Ba (368× 10^-6-3297.4×10^-6), Cr (65.5 ×10^-6-194.2 × 10^-6), Mo (5.6 × 10^-6-18.2× 10^-6), Hi (72.9 × 10^-6-152.9 × 10^-6) and V (245.5 × 10^-6-520 ×10^-6) are higher than world coal averages. However, low concentration of some vol- atile elements such as As, Hg and U are present in low concentrations of the various types of coal studied.
基金financially supported by the research project of the Czech Science Foundation(GA■R 17-17276S)“Tourmaline-an indicator of geological processes”supported by the institutional project RVO 67985831 of the Institute of Geology of the Czech Academy of Sciences,as well as by the Brno University of Technology project LO1408“Ad Ma S UP-Advanced Materials,Structures and Technologies”+1 种基金supported by the Ministry of Education,Youth and Sports CR under the“National Sustainability Programme I”financial support provided to the Moravian Museum by the Ministry of Culture of the Czech Republic as part of its long-term conceptual development programme for research institutions(ref.MK000094862)(S.H.)。
文摘Various metacarbonate and associated calc-silicate rocks form minor but genetically significant components of the lithological units in the Bohemian Massif of the Variscan orogen in Central Europe.These rocks vary in terms of their lithostratigraphy,chemical composition and mineral assemblage(dolomite/calcite ratio,silicate abundance).Tourmaline is present in five paragenetic settings within the metacarbonate and calc-silicate units.TypeⅠcomprises individual,euhedral,prismatic grains and grain aggregates in a carbonate-dominant(calcite±dolomite)matrix poor in silicates.TypeⅡis characterized by euhedral to subhedral grains and coarse-to fine-grained aggregates in silicate-rich layers/nests within metacarbonate bodies whereas typeⅢoccurs as prismatic grains and aggregates at the contact zones between carbonate and associated silicate host rocks.TypeⅣis in veins crosscutting metacarbonate bodies,and typeⅣtourmaline occurs at the exocontacts of elbaite-subtype granitic pegmatite.Tourmaline from the different settings shows distinctive compositional features.Typical for typeⅠare Mg-rich compositions,with fluor-uvite>dravite>>magnesio-lucchesiite.Tourmalines from typeⅡsilicate-rich layers/nests are highly variable,corresponding to oxy-schorl,magnesio-foitite,Al-rich dravite and fluor-uvite.Typical for typeⅢtourmalines are Ca,Ti-bearing oxy-dravite compositions.The typeⅣveins feature dravite and fluor-uvite tourmaline compositions whereas typeⅤtourmaline is Li,F-rich dravite.Tourmaline is the only Bbearing phase in paragenetic typesⅠ-Ⅳ,where it is characterised by two principal ranges of B-isotope composition(δ^11B=-13‰to-9‰and-18‰to-14‰).These ranges correspond to regionally different units of the Moldanubian Zone.Thus,the Svratka Unit(Moldanubian Zone s.l.)contains only isotopically lighter tourmaline(δ^11B=-18‰to-14‰),whereas metacarbonates in the Poli?ka unit(Teplá-Barrandian Zone)and Olesnice unit(Moravicum of the Moravo-Silesian Zone)has exclusively isotopically heavier tourmaline(δ^11B=-9‰to-13‰).Tourmalines from metacarbonates in the Variegated Unit cover both ranges of isotope composition.The isotopically light end of the B isotope range may indicate the presence of continental evaporites within individual investigated areas.On the other hand,variations in the range of~8δ-units is consistent with the reported shift in B isotopic composition of metasedimentary rocks of the Bohemian Massif due to the prograde metamorphism from very-low grade to eclogite facies.In contrast to the metacarbonate-hosted settings,tourmaline of paragenetic type V from the exocontact of granitic pegmatites displays a significantly heavier range ofδ^11B(as low as-7.7‰to-0.6‰),which is attributed to partitioning of 10 B to cogenetic axinite and/or different B-signature of the source pegmatite containing tourmaline with heavyδ^11B signature.
文摘Numerous investigations on submarine hydrothermal ore-forming occurrence have been actively carried out in the last two decades with significant results.The Ag and Au enrichments in the sulfides from black smokers ofhydrothermal vent field Broken Spur(MAR) aroused our interest to study their mineral hosting forms.Samples were collected from seven hydrothermal chimneys within Broken Spur in the British-Russian BRAVEX(1994) and
文摘In the last couple of years the Museum developed a project financed by the National Agency for Culture and Technology in partnership with four schools from Lisbon.The guidelines of this project were the climate change and its influence on human lives in our society and on other living beings."Changing climate, changing lives",our project,evolved 8 months work of about 150 high school grade students,in which