Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tong...Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tongren in Guizhou Province, Shan- grao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province contained high REE contents in phos- phorites, especially those from Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province. Among them, the highest REE contents reached up to 1361.59×10^-6 and P205 contents up to 29.45%. In contrast, phosphorites from Kaiyang, Qingzhen and Zhenyuan in Guizhou Province had relatively low total REE con- tents and low P205 contents, with the lowest total REE content of 53.19× 10^-6, and the lowest P205 content of 0.07%. REE contents exhibited a positive correlation with phosphorous contents, indicating a close genetic relationship between REE and phosphorous ele- ment. The main reason was the difference of the sedimentary environments and the contents of phosphorous and REE in deep water mass formed in upwelling currents, at an upper slope facies （Slu） in reducing condition due to relatively closed sedimentary environ- ment. It was very difficult for the upswelling phosphorous and REE to deposit, massive phosphorous deposits were hard to be formed. At a deep water ramp facies （DRa） in the ascending process of currents, phosphorus and REE underwent differentiation rather than sedimentation. Consequently, the contents of P205 sediments and REE were low. At a shallow water ramp facies （including shoals and tidal flats） （SRa）, with active seawater circulation and phosphatic supplement, sunny weather, high nutrition and rapid growth of algae, were benefitial for the physical enrichment of carbonate sediments. Therefore, massive phosphorite deposits were easy to be tbrmed with abundant REE minerals, and finally turned into high REE beating phosphorous deposits展开更多
The newly discovered Yangchongli gold deposit is a unique independent gold deposit in the Tongling ore-cluster region controlled by the tectonic alteration firstly discovered in the Lower Yangtze Metallogenic Belt （L...The newly discovered Yangchongli gold deposit is a unique independent gold deposit in the Tongling ore-cluster region controlled by the tectonic alteration firstly discovered in the Lower Yangtze Metallogenic Belt （LYMB）. The host magmatic rocks mainly consist of monzodiorite and K-feldspar granite. The LA-ICP-MS U-Pb zircons dating yielded weighted mean 206pb/23SU ages of 140.7 ± 1.8 Ma and 126.4 ±1.2 Ma for the monzodiorite and K-feldspar granite, respectively. Monzodiorites are enriched in Sr, Ba, Rb, and depleted in Y, Yb with high Sr/Y and La/Yb ratios, similar to the geochemical features of adakite, considered as products of differentiation of mafic magmas originating from lithospheric mantle melt/fluids caused by metasomatism during paleo-Pacific Plate subduction in the Mesozic. In contrast, the compositions of K-feldspar granites are A-type granites, indicating an extensional tectonic background. Gold ores hosted in the fracture zone occurred as quartz vein within cataclastic rock. Sulfur and lead isotopes from pyrites show crust-mantle mixing characteristics. Metal components from strata also took part in the gold mineralization, and resulted from two episodes of magmatism that were probably related to tectonic transition from a compressive to an extensional setting between 140-126 Ma, which led to the Mesozoic large-scale polymetallic mineralization events in eastern China.展开更多
基金Project supported by National Natural Science Foundation of China(50164001)the State Programs of Science and Technology Development funded by The Ministry of Science and Technology of China(2007BAB08B03)+3 种基金the Outstanding Scientific and Technological Talents Fund of Guizhou Province(2009008)the Graduates Innovation Fund of Guizhou University(2010009)the Youth Fund of Guizhou University(2009070)the Youth Fund of College of Resources and Environmental Engineering,Guizhou University(ZHY0901)
文摘Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tongren in Guizhou Province, Shan- grao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province contained high REE contents in phos- phorites, especially those from Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province. Among them, the highest REE contents reached up to 1361.59×10^-6 and P205 contents up to 29.45%. In contrast, phosphorites from Kaiyang, Qingzhen and Zhenyuan in Guizhou Province had relatively low total REE con- tents and low P205 contents, with the lowest total REE content of 53.19× 10^-6, and the lowest P205 content of 0.07%. REE contents exhibited a positive correlation with phosphorous contents, indicating a close genetic relationship between REE and phosphorous ele- ment. The main reason was the difference of the sedimentary environments and the contents of phosphorous and REE in deep water mass formed in upwelling currents, at an upper slope facies （Slu） in reducing condition due to relatively closed sedimentary environ- ment. It was very difficult for the upswelling phosphorous and REE to deposit, massive phosphorous deposits were hard to be formed. At a deep water ramp facies （DRa） in the ascending process of currents, phosphorus and REE underwent differentiation rather than sedimentation. Consequently, the contents of P205 sediments and REE were low. At a shallow water ramp facies （including shoals and tidal flats） （SRa）, with active seawater circulation and phosphatic supplement, sunny weather, high nutrition and rapid growth of algae, were benefitial for the physical enrichment of carbonate sediments. Therefore, massive phosphorite deposits were easy to be tbrmed with abundant REE minerals, and finally turned into high REE beating phosphorous deposits
基金supported by the DREAM project of MOST China (No.2016YFC0600404)the Natural Science Foundation of China (Grant Nos.41372087, 41673040)the Project of Geological Science and Technology of Anhui Province (2015-K-01)
文摘The newly discovered Yangchongli gold deposit is a unique independent gold deposit in the Tongling ore-cluster region controlled by the tectonic alteration firstly discovered in the Lower Yangtze Metallogenic Belt （LYMB）. The host magmatic rocks mainly consist of monzodiorite and K-feldspar granite. The LA-ICP-MS U-Pb zircons dating yielded weighted mean 206pb/23SU ages of 140.7 ± 1.8 Ma and 126.4 ±1.2 Ma for the monzodiorite and K-feldspar granite, respectively. Monzodiorites are enriched in Sr, Ba, Rb, and depleted in Y, Yb with high Sr/Y and La/Yb ratios, similar to the geochemical features of adakite, considered as products of differentiation of mafic magmas originating from lithospheric mantle melt/fluids caused by metasomatism during paleo-Pacific Plate subduction in the Mesozic. In contrast, the compositions of K-feldspar granites are A-type granites, indicating an extensional tectonic background. Gold ores hosted in the fracture zone occurred as quartz vein within cataclastic rock. Sulfur and lead isotopes from pyrites show crust-mantle mixing characteristics. Metal components from strata also took part in the gold mineralization, and resulted from two episodes of magmatism that were probably related to tectonic transition from a compressive to an extensional setting between 140-126 Ma, which led to the Mesozoic large-scale polymetallic mineralization events in eastern China.
