Diagenetic-metallogenic ages of pyritic cherts formed by the syn-sedimentation of hydrothermal vent and ages of the Jinchang Rock Formation in the Mojiang large nickel-gold deposit in the Ailaoshan gold metallogenic b...Diagenetic-metallogenic ages of pyritic cherts formed by the syn-sedimentation of hydrothermal vent and ages of the Jinchang Rock Formation in the Mojiang large nickel-gold deposit in the Ailaoshan gold metallogenic belt have been discussed on the basis of chronology of isotopic geochemistry. Nickel-gold-bearing pyritic cherts in the mining were formed by syn-sedimentation of hydrothermal vent in the Late Devonian, i.e. age by Sm-Nd isochronal method (t) = (358±8.6) (2σ) Ma and age by Rb-Sr isochronal method (t) = (354.7±0.72) (2σ) Ma. On the other hand, deep-water cherts from the Jinchang Rock Formation of the Upper Devonian in the area were initiated at the same time; that is, age by Sm-Nd isochronal method (t) = (359(+21) (2(7) Ma and age by Rb-Sr isochronal method (t) = (358.02±0.30) (2σ) Ma.展开更多
Geological and geochemical characteristics of cherts of the low\|middle parts of the Jinchang Formation indicate that cherts are associated with hydrothermal sedimentation, but the middle\|upper parts of the Jinchang ...Geological and geochemical characteristics of cherts of the low\|middle parts of the Jinchang Formation indicate that cherts are associated with hydrothermal sedimentation, but the middle\|upper parts of the Jinchang Formation are mixed with normal sediments. The cherts are characterized by high Fe, As, Sb, Bi and Ga, low Al and total REE, negative Ce anomaly and HREE enrichment. Their \{δ\{\}\+\{18\}O\} values show that the forming temperatures of the cherts range from 128 ℃ to 146 ℃.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grants No. 49925309)the State Key Project of Fundamental Research Planning (Grants No. 1999043200) and the Yunnan Province-Chinese Academy of Sciences Corporation Project (G
文摘Diagenetic-metallogenic ages of pyritic cherts formed by the syn-sedimentation of hydrothermal vent and ages of the Jinchang Rock Formation in the Mojiang large nickel-gold deposit in the Ailaoshan gold metallogenic belt have been discussed on the basis of chronology of isotopic geochemistry. Nickel-gold-bearing pyritic cherts in the mining were formed by syn-sedimentation of hydrothermal vent in the Late Devonian, i.e. age by Sm-Nd isochronal method (t) = (358±8.6) (2σ) Ma and age by Rb-Sr isochronal method (t) = (354.7±0.72) (2σ) Ma. On the other hand, deep-water cherts from the Jinchang Rock Formation of the Upper Devonian in the area were initiated at the same time; that is, age by Sm-Nd isochronal method (t) = (359(+21) (2(7) Ma and age by Rb-Sr isochronal method (t) = (358.02±0.30) (2σ) Ma.
文摘Geological and geochemical characteristics of cherts of the low\|middle parts of the Jinchang Formation indicate that cherts are associated with hydrothermal sedimentation, but the middle\|upper parts of the Jinchang Formation are mixed with normal sediments. The cherts are characterized by high Fe, As, Sb, Bi and Ga, low Al and total REE, negative Ce anomaly and HREE enrichment. Their \{δ\{\}\+\{18\}O\} values show that the forming temperatures of the cherts range from 128 ℃ to 146 ℃.
