The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a hi...The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a high-grade w(MnO)=8.92% to 18.76%) manganese deposit with low-phosphorus w(P2O5)=0.08% to 0.16%) content. It also has a low total REEs contents(with an average of 101.3×10-6), and has inconspicuous Ce(0.81 to 1.29) and Eu(1.00 to 1.25) anomalies. lg(Ce/Ce*) values are from-0.02 to 0.11. The ores have high SiO2/Al2O3 and Al/(Al + Fe + Mn) ratios. In figures of Fe–Mn–[(Ni+Cu+Co)×10] and lgU–lgTh, all samples show that hydrothermal exhalative fluids played an important role during mineralisation. The δ13CPDB and δ18OSMOW values of eight ore samples are from-20.7‰ to-8.2‰(with an average of-12.4‰) and from 14.3‰ to 18.7‰(with an average of 17.0‰), respectively. These carbon and oxygen isotopic features indicate that hydrothermal fluids derived from deep earth are participation in the metallogenic process, which is also supported by high paleo-seawater temperatures varying from 47.08 to 73.98 °C. Therefore, the geological and geochemical evidences show that the Qujiashan deposit formed from submarine exhalative hydrothermal sedimentation.展开更多
The Wadi Bayhan mafic-uhramafic intrusions associated with magmatic PGE-bearing Cu-Ni sulphide deposit are located in the south margin of the Arabian-Nubian Shield, SW Yemen. The intrusions consist of du- nite, olivin...The Wadi Bayhan mafic-uhramafic intrusions associated with magmatic PGE-bearing Cu-Ni sulphide deposit are located in the south margin of the Arabian-Nubian Shield, SW Yemen. The intrusions consist of du- nite, olivine-pyroxenite, lherzolite, hornblendite, gabbro and gabbronorite. The dunite and lherzolite are the main host rock for the Cu-Ni ores. The new data of the chemical compositions of the rocks have SiO2 （50% - 53.6% ）, AI203 （0-32%） and MgO （4%-28%）, and relatively low TiO2 （0-3.2%） and K2 0 ＋ Na20 （0. 04% - 5.2% ）. The geochemical characteristics indicate that the parental magma is high-magnesium tholeiitic. Sulfur had reached saturation and immiscible sulfides droplets segregated from silicate magmas before their emplacement.展开更多
基金Project(41663006)supported by the National Natural Science Foundation of ChinaProject(1212011220725)supported by the Geological Survey Project of the China Geological Survey
文摘The Qujiashan manganese deposit is located in the Longmen-Daba fold belt along the northern margin of the Yangtze Block. The layered ore bodies are distributed within the purple-red calcareous shale. Qujiashan is a high-grade w(MnO)=8.92% to 18.76%) manganese deposit with low-phosphorus w(P2O5)=0.08% to 0.16%) content. It also has a low total REEs contents(with an average of 101.3×10-6), and has inconspicuous Ce(0.81 to 1.29) and Eu(1.00 to 1.25) anomalies. lg(Ce/Ce*) values are from-0.02 to 0.11. The ores have high SiO2/Al2O3 and Al/(Al + Fe + Mn) ratios. In figures of Fe–Mn–[(Ni+Cu+Co)×10] and lgU–lgTh, all samples show that hydrothermal exhalative fluids played an important role during mineralisation. The δ13CPDB and δ18OSMOW values of eight ore samples are from-20.7‰ to-8.2‰(with an average of-12.4‰) and from 14.3‰ to 18.7‰(with an average of 17.0‰), respectively. These carbon and oxygen isotopic features indicate that hydrothermal fluids derived from deep earth are participation in the metallogenic process, which is also supported by high paleo-seawater temperatures varying from 47.08 to 73.98 °C. Therefore, the geological and geochemical evidences show that the Qujiashan deposit formed from submarine exhalative hydrothermal sedimentation.
文摘The Wadi Bayhan mafic-uhramafic intrusions associated with magmatic PGE-bearing Cu-Ni sulphide deposit are located in the south margin of the Arabian-Nubian Shield, SW Yemen. The intrusions consist of du- nite, olivine-pyroxenite, lherzolite, hornblendite, gabbro and gabbronorite. The dunite and lherzolite are the main host rock for the Cu-Ni ores. The new data of the chemical compositions of the rocks have SiO2 （50% - 53.6% ）, AI203 （0-32%） and MgO （4%-28%）, and relatively low TiO2 （0-3.2%） and K2 0 ＋ Na20 （0. 04% - 5.2% ）. The geochemical characteristics indicate that the parental magma is high-magnesium tholeiitic. Sulfur had reached saturation and immiscible sulfides droplets segregated from silicate magmas before their emplacement.
