The garnet muscovite granitic pegmatite of Um Solimate,in southern Egypt,represents a promising asset for strategic and economic metals,especially Bi-Ni-Ag-Nb-Ta as well as U and Th.The ore bodies occur as large masse...The garnet muscovite granitic pegmatite of Um Solimate,in southern Egypt,represents a promising asset for strategic and economic metals,especially Bi-Ni-Ag-Nb-Ta as well as U and Th.The ore bodies occur as large masses,pockets and/or veins of very coarse-grained pegmatites,which consist mainly of K-feldspar,quartz and albite with subordinate muscovite,garnet,and biotite.Radiometric data revealed that e U-and e Th-contents of the pegmatites reach up to 39 ppm and 82 ppm,respectively.The studied pegmatites are enriched in primary U and Th minerals(uraninite,coffinite,thorianite and uranothorite)as well as Hf-rich zircon and monazite,which give rise to anomalous radioactive zones.Niobium-tantalium-bearing minerals(i.e.ferrocolumbite,microlite and uranopyrochlore),xenotime,barite,galena,fluorite,and apatite are ubiquitous,and,consequently,the studied pegmatites belong tothe Niobium-Yttrium-Fluorine-type(NYF)family.The noble metal mineralization includes argentite(Ag_(2)S),native Ni and Bi as well as bismite and bismoclite.In addition,beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic bodies.The observed compositional variations of Ta/(Ta+Nb)and Mn/(Mn+Fe)ratios in columbite(0.08-0.45 and 0.11-0.57,respectively)and Hf contents in zircon(3.54-6.46 wt%)may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.展开更多
Um Solimate emerald deposit is a unique example for the well-known beryl-related schist type.Where,the Be-mineralization is restricted to NNE-trending quartz veins/lenses and as disseminated emerald grains within the ...Um Solimate emerald deposit is a unique example for the well-known beryl-related schist type.Where,the Be-mineralization is restricted to NNE-trending quartz veins/lenses and as disseminated emerald grains within the altered-metasomatic zones of phlogopite-and graphite-schists.The study of fluid inclusions for the mineralized quartz vein revealed three major groups:(i)aqueous(H_(2)O-NaCl),(ii)aqueous-carbonic(H_(2)O-CO_(2)-[CH_(4)]-NaCl),and(iii)aqueous-hydrocarbonic(H_(2)O-CH_(4))FIs.They have been further classified into five types(namely:types 1,2,3,4 and 5)according to number of phases at the room temperature(20℃)as well as microthermometric measurements.Based upon the study of fluid inclusions,the initial-ore forming fluid was supposed to be of magmatic nature,characterized by a relatively high temperature of homogenization(T_(h,tot):269–485℃)and higher salinity(8.4 wt.%–9.6 wt.%NaCl equiv.),followed by development of aqueous-carbonic inclusions at lower temperature(T_(h,tot):241–355℃)and lower salinity(3.3 wt.%–4.9 wt.%NaCl equiv.)through metamorphic dehydration/decarbonation.Methane-rich FIs were suggested to be formed as a result of local re-equilibration of graphite in reduced environment at the contact aureole of the felsic intrusion.The P-T conditions of ore formation were estimated as modal temperature between(330–370℃)and fluid pressures of about 200 MPa,corresponding to an estimated depth ranges from 7 to 10 km.The formation of emerald is closely associated with multiple events through the ore evolution,the deposition is ascribed to destabilization process of continuous metasomatic interactions and elemental substitutions between felsic-derived Be-bearing fluids with the adjacent mafic-ultramafic rocks at the zone of mineralization.展开更多
Many environmental variables are frequently used to predict values of soil in locations where they are not measured. Digital soil mapping (DSM) has a long-standing convention to describe soils as a function of climate...Many environmental variables are frequently used to predict values of soil in locations where they are not measured. Digital soil mapping (DSM) has a long-standing convention to describe soils as a function of climate, organisms, topography, parent material, time and space. It is obvious that terrain, climate, parent material and organisms are used frequently in the prediction of soil properties while time and space factors are rarely used. Time is the indirect factor for the formation and development of soil. Moreover, it is very useful to explicit and implicit estimates of soil age for DSM. However, it is often difficult to obtain time factor. In the absence of explicit soil age data, geomorphologic data are commonly related to soil relative age. Consequently, this study adopts the geomorphologic types (genesis type of geomorphology) as surrogate to the time factor and analyzes its effect on DSM. To examine this idea, we selected the Ili region of northwestern China as the study area. This paper uses geomorphologic data from a new digital geomorphology map as the implicit soil age in predictive soil mapping. For this study, Soil-landscape inference model (SoLIM) was used to predict soil properties based on the individual representation of each sample. This model applies the terrain (topography), climate, parent material (geology) and time (geomorphologic type) to predict soil values in the study area where they are not measured. And the independent sample validation method was used to estimate the precision of results. The validation result shows that the use of geomorphologic data as surrogate to the time factor in the individual representation leads to a considerable and significant increase in the accuracy of results. In other words, implicit estimates of soil age by genesis type of geomorphology are very useful for DSM. This increase was due to the high purity of the geomorphologic data. This means that the geomorphologic variable, if used, can improve the quality of DSM. Predicted value through the proposed approach comes closer to the real value.展开更多
文摘The garnet muscovite granitic pegmatite of Um Solimate,in southern Egypt,represents a promising asset for strategic and economic metals,especially Bi-Ni-Ag-Nb-Ta as well as U and Th.The ore bodies occur as large masses,pockets and/or veins of very coarse-grained pegmatites,which consist mainly of K-feldspar,quartz and albite with subordinate muscovite,garnet,and biotite.Radiometric data revealed that e U-and e Th-contents of the pegmatites reach up to 39 ppm and 82 ppm,respectively.The studied pegmatites are enriched in primary U and Th minerals(uraninite,coffinite,thorianite and uranothorite)as well as Hf-rich zircon and monazite,which give rise to anomalous radioactive zones.Niobium-tantalium-bearing minerals(i.e.ferrocolumbite,microlite and uranopyrochlore),xenotime,barite,galena,fluorite,and apatite are ubiquitous,and,consequently,the studied pegmatites belong tothe Niobium-Yttrium-Fluorine-type(NYF)family.The noble metal mineralization includes argentite(Ag_(2)S),native Ni and Bi as well as bismite and bismoclite.In addition,beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic bodies.The observed compositional variations of Ta/(Ta+Nb)and Mn/(Mn+Fe)ratios in columbite(0.08-0.45 and 0.11-0.57,respectively)and Hf contents in zircon(3.54-6.46 wt%)may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.
基金conducted through post-doctoral fellowship scheme granted by “TüB?TAK 2221 ” fellowship in Turkey
文摘Um Solimate emerald deposit is a unique example for the well-known beryl-related schist type.Where,the Be-mineralization is restricted to NNE-trending quartz veins/lenses and as disseminated emerald grains within the altered-metasomatic zones of phlogopite-and graphite-schists.The study of fluid inclusions for the mineralized quartz vein revealed three major groups:(i)aqueous(H_(2)O-NaCl),(ii)aqueous-carbonic(H_(2)O-CO_(2)-[CH_(4)]-NaCl),and(iii)aqueous-hydrocarbonic(H_(2)O-CH_(4))FIs.They have been further classified into five types(namely:types 1,2,3,4 and 5)according to number of phases at the room temperature(20℃)as well as microthermometric measurements.Based upon the study of fluid inclusions,the initial-ore forming fluid was supposed to be of magmatic nature,characterized by a relatively high temperature of homogenization(T_(h,tot):269–485℃)and higher salinity(8.4 wt.%–9.6 wt.%NaCl equiv.),followed by development of aqueous-carbonic inclusions at lower temperature(T_(h,tot):241–355℃)and lower salinity(3.3 wt.%–4.9 wt.%NaCl equiv.)through metamorphic dehydration/decarbonation.Methane-rich FIs were suggested to be formed as a result of local re-equilibration of graphite in reduced environment at the contact aureole of the felsic intrusion.The P-T conditions of ore formation were estimated as modal temperature between(330–370℃)and fluid pressures of about 200 MPa,corresponding to an estimated depth ranges from 7 to 10 km.The formation of emerald is closely associated with multiple events through the ore evolution,the deposition is ascribed to destabilization process of continuous metasomatic interactions and elemental substitutions between felsic-derived Be-bearing fluids with the adjacent mafic-ultramafic rocks at the zone of mineralization.
文摘Many environmental variables are frequently used to predict values of soil in locations where they are not measured. Digital soil mapping (DSM) has a long-standing convention to describe soils as a function of climate, organisms, topography, parent material, time and space. It is obvious that terrain, climate, parent material and organisms are used frequently in the prediction of soil properties while time and space factors are rarely used. Time is the indirect factor for the formation and development of soil. Moreover, it is very useful to explicit and implicit estimates of soil age for DSM. However, it is often difficult to obtain time factor. In the absence of explicit soil age data, geomorphologic data are commonly related to soil relative age. Consequently, this study adopts the geomorphologic types (genesis type of geomorphology) as surrogate to the time factor and analyzes its effect on DSM. To examine this idea, we selected the Ili region of northwestern China as the study area. This paper uses geomorphologic data from a new digital geomorphology map as the implicit soil age in predictive soil mapping. For this study, Soil-landscape inference model (SoLIM) was used to predict soil properties based on the individual representation of each sample. This model applies the terrain (topography), climate, parent material (geology) and time (geomorphologic type) to predict soil values in the study area where they are not measured. And the independent sample validation method was used to estimate the precision of results. The validation result shows that the use of geomorphologic data as surrogate to the time factor in the individual representation leads to a considerable and significant increase in the accuracy of results. In other words, implicit estimates of soil age by genesis type of geomorphology are very useful for DSM. This increase was due to the high purity of the geomorphologic data. This means that the geomorphologic variable, if used, can improve the quality of DSM. Predicted value through the proposed approach comes closer to the real value.
