The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,...The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,Shaziling and Xishan)yielded similar ages of approximately 153 Ma,indicating indistinguishable ages within error.Three plutons except the Shaziling pluton,have consistentε_(Nd)(t)(-7.8 to-5.8)andε_(Hf)(t)(-9.1 to-2.2)values,which are similar to those of the lower crustal granulitic metasedimentary and meta-igneous rocks in South China.Compared to other three plutons,the Shaziling pluton has consistentε_(Nd)(t)(-7.4 to-6.8)andε_(Hf)(t)(-7.5 to-4.7)values and shows similar source,but the Shaziling mafic microgranular enclaves(MMEs)show variableε_(Hf)(t)(-14.2 to 4.8)values,indicating a remarkable mantle magma injection of the Shaziling pluton.Zircon Ce/Sm-Yb/Gd,whole-rock CaO-P_(2)O_(5)and CaO-TiO_(2)linear trends reveal that from the Xishan to the Shaziling and from the Jinjiling to the Pangxiemu granites,they experienced apatite and titanite fractionation,respectively.Zircon Th,U,Nb,Ta,Hf,Ti,Y,P and rare earth element(REE)contents and whole-rock Sr,Ba and Rb contents also show that the Shaziling,Xishan,Jinjiling and Pangxiemu granites followed a discontinuous evolutionary series,but the Pangxiemu granites exhibit highly evolved nature.Four main controlling factors of W-Sn and rare metal mineralization in granitic rocks were discussed,and we found that the mineralization in Jiuyishan granitic complex was mainly controlled by the fractionation degree and crystallization temperature,but were rarely affected by oxygen fugacity and mantle material input.The Pangxiemu granites show particularly higher Rb and Ta contents than the other three plutons,implying that the ore deposits developed in the Jiuyishan Complex were directly related to the most evolved Pangxiemu pluton,with the occurrence of Rb and Ta as the most likely rare metal mineralization in the Jiuyishan District.A crystal mush model is proposed to interpret the petrogenetic and mineralizing processes of the Jiuyishan granitic complex.展开更多
The Baïbokoum-Touboro-Ngaoundaye area is located in the Adamoua-Yade domain of the Pan-African Fold Belt in Central Africa. The present work concerns the petrographic and geochemical study. The study area is ...The Baïbokoum-Touboro-Ngaoundaye area is located in the Adamoua-Yade domain of the Pan-African Fold Belt in Central Africa. The present work concerns the petrographic and geochemical study. The study area is made up of plutonic rocks including two amphibole granites, four biotite and muscovite granites, two syenites and one monzonite sample. These rocks have a granular porphyroid texture, with a mylonitic tendency. The primary paragenesis consists of Opx + Cpx + Amp + Bt + Pl + Or + Mic + Qtz + Ap + Sph + Zr and the secondary paragenesis consisting of Ch + Op. Plutonic rocks are shoshonitic to calc-alkaline with a strong potassic affinity. The REE profiles of these rocks show a negative anomaly of Eu in the granites and no Eu anomaly in syenites and monzonite (syeno-diorite). Multielement spectra of plutonic rocks present a negative anomaly in Nb-Ta and Ti. Fractional crystallization is the process that made these rocks of study area. These rocks are placed in a subduction to syn-collisional (VAG + Syn-COLG) and of intraplate granitoids (WPG) environment.展开更多
A highly-fractionated garnet-bearing muscovite granite represents the marginal granitic facies of the Abu-Diab multiphase pluton in the Central Eastern Desert of Egypt. New electron microprobe analyses(EMPA) and laser...A highly-fractionated garnet-bearing muscovite granite represents the marginal granitic facies of the Abu-Diab multiphase pluton in the Central Eastern Desert of Egypt. New electron microprobe analyses(EMPA) and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) data from garnets are reported, in order to constrain their origin and genesis. Garnet in the Abu-Diab host granite is euhedral to subhedral, generally homogeneous and, in rare cases, it shows weak zonation. The garnet contains appreciable amounts of MnO and FeO, with lesser amounts of MgO and CaO, yielding an end-member formula of Sps61–72Alm25–35Prp1–4Adr0–1. Moreover, it is depleted in large ion lithophile elements(LILE) with lower values of Ba, Nb and Sr relative to the primitive mantle. Additionally, it contains high concentrations of HREE and Y and their REE pattern shows strong negative Eu anomalies. The garnet was crystallized under relatively low temperature(646°C–591°C) and pressure(< 3 kbar) conditions. The textural and chemical features indicate that the garnet is magmatic in origin and is chemically similar to that from highly-fractionated A-type granite. It was probably formed at the expense of biotite in a highly-evolved MnO-rich magma and/or by hydroxyl complexing of Mn during the ascending fluid phases.展开更多
The rare metals of Abu Dabbab area in the Central Eastern Desert of Egypt have been investigated for their mineralogy and conditions of precipitation using combination of EMPA and fluid inclusions studies,in order to ...The rare metals of Abu Dabbab area in the Central Eastern Desert of Egypt have been investigated for their mineralogy and conditions of precipitation using combination of EMPA and fluid inclusions studies,in order to delineate the source,mechanism of formation and evolutionary model for these economic metals.The(Ta-Nb-Sn)-bearing minerals at the Abu Dabbab area include columbite group minerals(CGMs),wodginite and cassiterite.In both granitic intrusion and its enclosed quartz veins,most of zoned CGMs and cassiterite grains are commonly characterized by a well-developed twostage texture.Hence,columbite-(Mn)(CGM-Ⅰ)represents the early formed phase of CGMs that is characterized by high Mn#values(0.64-0.92)with quite low Ta#values(0.13-0.49).It was invaded by Ta-rich phases including tantalite-(Mn)(CGM-Ⅱ;Ta#=0.13-0.49)and wodginite,which contain high Ta_(2)O_(5)and SnO_(2)(17.91 wt.%).In regard to cassiterite,there are distinct compositional differences between the early-phase cassiterite(Cst-Ⅰ)and the late-phase one(Cst-Ⅱ),where the latter is enriched in Ta_(2)O_(5),Nb_(2)O_(5)and FeO.The chemistry and textural criteria of the early stage CGM-Ⅰand Cst-Ⅰ,all are indicative of magmatic origin.While,the latter CGM-Ⅱ,wodginite and Cst-Ⅱwere influenced by the late magmatic Ta-rich fluids.Fluid inclusions microthermometry shows criteria of phase separation represented by both boiling and fluid immiscibility.The initial fluid was supposed to be of magmatic origin(magmatic CH4),that was consequently influenced by fluid mixing/dilution with post-hydrothermal/meteoric water with respect to the decompression process during uplift.Isochore construction gave rise to an estimate P-T conditions(T=330-370℃,P=22-50 MPa).The fluid inclusions’microthermometry supports a transition between magmatic and late to post-hydrothermal activities in addition to surface-derived fluid(meteoric fluid?)in a part as main source for the polymetallic deposits.展开更多
基金financially supported by the Provincial Natural Science Foundation of Hunan(Nos.2019JJ50831,2023JJ30505 and 2023JJ40541)the China Postdoctoral Science Foundation(Nos.2017M622597 and 2021M690591)+2 种基金the Open Research Fund Program of Fundamental Science on Radioactive Geology and Exploration Technology Laboratory(East China University of Technology)(No.2022RGET04)the National Foreign Expert Project(No.G2022029012L)the National Nature Science Foundation of China(No.41002022)。
文摘The Jiuyishan granitic complex,located in the Nanling Range,South China,is composed of five granitic plutons(Xuehuading,Jinjiling,Pangxiemu,Shaziling and Xishan).Zircon U-Pb dating of four plutons(Jinjiling,Pangxiemu,Shaziling and Xishan)yielded similar ages of approximately 153 Ma,indicating indistinguishable ages within error.Three plutons except the Shaziling pluton,have consistentε_(Nd)(t)(-7.8 to-5.8)andε_(Hf)(t)(-9.1 to-2.2)values,which are similar to those of the lower crustal granulitic metasedimentary and meta-igneous rocks in South China.Compared to other three plutons,the Shaziling pluton has consistentε_(Nd)(t)(-7.4 to-6.8)andε_(Hf)(t)(-7.5 to-4.7)values and shows similar source,but the Shaziling mafic microgranular enclaves(MMEs)show variableε_(Hf)(t)(-14.2 to 4.8)values,indicating a remarkable mantle magma injection of the Shaziling pluton.Zircon Ce/Sm-Yb/Gd,whole-rock CaO-P_(2)O_(5)and CaO-TiO_(2)linear trends reveal that from the Xishan to the Shaziling and from the Jinjiling to the Pangxiemu granites,they experienced apatite and titanite fractionation,respectively.Zircon Th,U,Nb,Ta,Hf,Ti,Y,P and rare earth element(REE)contents and whole-rock Sr,Ba and Rb contents also show that the Shaziling,Xishan,Jinjiling and Pangxiemu granites followed a discontinuous evolutionary series,but the Pangxiemu granites exhibit highly evolved nature.Four main controlling factors of W-Sn and rare metal mineralization in granitic rocks were discussed,and we found that the mineralization in Jiuyishan granitic complex was mainly controlled by the fractionation degree and crystallization temperature,but were rarely affected by oxygen fugacity and mantle material input.The Pangxiemu granites show particularly higher Rb and Ta contents than the other three plutons,implying that the ore deposits developed in the Jiuyishan Complex were directly related to the most evolved Pangxiemu pluton,with the occurrence of Rb and Ta as the most likely rare metal mineralization in the Jiuyishan District.A crystal mush model is proposed to interpret the petrogenetic and mineralizing processes of the Jiuyishan granitic complex.
文摘The Baïbokoum-Touboro-Ngaoundaye area is located in the Adamoua-Yade domain of the Pan-African Fold Belt in Central Africa. The present work concerns the petrographic and geochemical study. The study area is made up of plutonic rocks including two amphibole granites, four biotite and muscovite granites, two syenites and one monzonite sample. These rocks have a granular porphyroid texture, with a mylonitic tendency. The primary paragenesis consists of Opx + Cpx + Amp + Bt + Pl + Or + Mic + Qtz + Ap + Sph + Zr and the secondary paragenesis consisting of Ch + Op. Plutonic rocks are shoshonitic to calc-alkaline with a strong potassic affinity. The REE profiles of these rocks show a negative anomaly of Eu in the granites and no Eu anomaly in syenites and monzonite (syeno-diorite). Multielement spectra of plutonic rocks present a negative anomaly in Nb-Ta and Ti. Fractional crystallization is the process that made these rocks of study area. These rocks are placed in a subduction to syn-collisional (VAG + Syn-COLG) and of intraplate granitoids (WPG) environment.
文摘A highly-fractionated garnet-bearing muscovite granite represents the marginal granitic facies of the Abu-Diab multiphase pluton in the Central Eastern Desert of Egypt. New electron microprobe analyses(EMPA) and laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) data from garnets are reported, in order to constrain their origin and genesis. Garnet in the Abu-Diab host granite is euhedral to subhedral, generally homogeneous and, in rare cases, it shows weak zonation. The garnet contains appreciable amounts of MnO and FeO, with lesser amounts of MgO and CaO, yielding an end-member formula of Sps61–72Alm25–35Prp1–4Adr0–1. Moreover, it is depleted in large ion lithophile elements(LILE) with lower values of Ba, Nb and Sr relative to the primitive mantle. Additionally, it contains high concentrations of HREE and Y and their REE pattern shows strong negative Eu anomalies. The garnet was crystallized under relatively low temperature(646°C–591°C) and pressure(< 3 kbar) conditions. The textural and chemical features indicate that the garnet is magmatic in origin and is chemically similar to that from highly-fractionated A-type granite. It was probably formed at the expense of biotite in a highly-evolved MnO-rich magma and/or by hydroxyl complexing of Mn during the ascending fluid phases.
基金Ministry of Higher Education of Egypt for supporting his research stay at University of Vienna(Austria)as a postdoctoral fellow。
文摘The rare metals of Abu Dabbab area in the Central Eastern Desert of Egypt have been investigated for their mineralogy and conditions of precipitation using combination of EMPA and fluid inclusions studies,in order to delineate the source,mechanism of formation and evolutionary model for these economic metals.The(Ta-Nb-Sn)-bearing minerals at the Abu Dabbab area include columbite group minerals(CGMs),wodginite and cassiterite.In both granitic intrusion and its enclosed quartz veins,most of zoned CGMs and cassiterite grains are commonly characterized by a well-developed twostage texture.Hence,columbite-(Mn)(CGM-Ⅰ)represents the early formed phase of CGMs that is characterized by high Mn#values(0.64-0.92)with quite low Ta#values(0.13-0.49).It was invaded by Ta-rich phases including tantalite-(Mn)(CGM-Ⅱ;Ta#=0.13-0.49)and wodginite,which contain high Ta_(2)O_(5)and SnO_(2)(17.91 wt.%).In regard to cassiterite,there are distinct compositional differences between the early-phase cassiterite(Cst-Ⅰ)and the late-phase one(Cst-Ⅱ),where the latter is enriched in Ta_(2)O_(5),Nb_(2)O_(5)and FeO.The chemistry and textural criteria of the early stage CGM-Ⅰand Cst-Ⅰ,all are indicative of magmatic origin.While,the latter CGM-Ⅱ,wodginite and Cst-Ⅱwere influenced by the late magmatic Ta-rich fluids.Fluid inclusions microthermometry shows criteria of phase separation represented by both boiling and fluid immiscibility.The initial fluid was supposed to be of magmatic origin(magmatic CH4),that was consequently influenced by fluid mixing/dilution with post-hydrothermal/meteoric water with respect to the decompression process during uplift.Isochore construction gave rise to an estimate P-T conditions(T=330-370℃,P=22-50 MPa).The fluid inclusions’microthermometry supports a transition between magmatic and late to post-hydrothermal activities in addition to surface-derived fluid(meteoric fluid?)in a part as main source for the polymetallic deposits.
