The Dongping deposit is the largest alkalic-hosted gold deposit in China containing>100 t of Au.This paper presents a new understanding for Dongping ore system,based on the previous studies.The mineralization origi...The Dongping deposit is the largest alkalic-hosted gold deposit in China containing>100 t of Au.This paper presents a new understanding for Dongping ore system,based on the previous studies.The mineralization originally occurred at 400-380 Ma,simultaneous with emplacement of the Shuiquangou alkaline complex,and was overprinted by the hydrothermal activity in the Yanshanian.Isotope compositions of ores indicate metals of the deposit are mainly provided by the Shuiquangou complex.Ore-forming fluids are characterized by increasing oxygen fugacity and decreasing sulfur fugacity,while tellurium fugacity increased in the Stage II-2 and decreased in Stage II-3.These systematic changes are closely related to the processes of mineral precipitation and fluid evolution.Sulfide precipitation from Stage Ⅰ to Stage Ⅱ was triggered by fluid boiling,which leads to the precipitation of Pb-Bi-Te,due to decrement of sulfur fugacity.Condensation of gas phase containing high concentration of H_2Te leads to precipitation of Te-Au-Ag minerals and native tellurium.Based on these hypotheses,this paper present a polyphase metallogenic model as follow.During the Devonian,fluids were released from alkaline magmas,which carried ore-forming materials form the surrounding rocks and precipitate the early ores.During the Jurassic-Cretaceous,fluorine-rich fluids exsolved from highly factionated Shangshuiquan granite,which extracted and concentrated Au from the Shuiquangou complex and the Sanggan Group metamorphic rocks,and finally formed the Dongping gold deposit.展开更多
In this paper, the Dongchuan type copper deposits are taken as an example to illustrate the application of GIS to the geo anomaly based delineation of mineral resources. The following eight steps are listed in this pa...In this paper, the Dongchuan type copper deposits are taken as an example to illustrate the application of GIS to the geo anomaly based delineation of mineral resources. The following eight steps are listed in this paper to delineate the permissive and preferable ore finding areas: (1) the analysis of favorable prospecting index using linear and planar geo anomalies; (2) the analysis of favorable prospecting index using combined anomalies; (3) the construction of a GIS based spatial model for mineral prognosis; (4) the delineation of the permissive ore finding area; (5) the determination of the synthetic anomalies and numerical range for the prediction of the favorable prospecting areas, and the determination of the weights of these two variables; (6) the superimposition of all the selected anomalies and the construction of the superimposition map; (7) the determination of unifying criterion of favorable prospective areas at various levels, and (8) the delineation of favorable prospective areas. Finally, this paper offers a detailed discussion of the results in the forecasting of Dongchuan type copper deposits.展开更多
基金financially supported by the project of the China Geological Survey(DD20230292,DD20242591)。
文摘The Dongping deposit is the largest alkalic-hosted gold deposit in China containing>100 t of Au.This paper presents a new understanding for Dongping ore system,based on the previous studies.The mineralization originally occurred at 400-380 Ma,simultaneous with emplacement of the Shuiquangou alkaline complex,and was overprinted by the hydrothermal activity in the Yanshanian.Isotope compositions of ores indicate metals of the deposit are mainly provided by the Shuiquangou complex.Ore-forming fluids are characterized by increasing oxygen fugacity and decreasing sulfur fugacity,while tellurium fugacity increased in the Stage II-2 and decreased in Stage II-3.These systematic changes are closely related to the processes of mineral precipitation and fluid evolution.Sulfide precipitation from Stage Ⅰ to Stage Ⅱ was triggered by fluid boiling,which leads to the precipitation of Pb-Bi-Te,due to decrement of sulfur fugacity.Condensation of gas phase containing high concentration of H_2Te leads to precipitation of Te-Au-Ag minerals and native tellurium.Based on these hypotheses,this paper present a polyphase metallogenic model as follow.During the Devonian,fluids were released from alkaline magmas,which carried ore-forming materials form the surrounding rocks and precipitate the early ores.During the Jurassic-Cretaceous,fluorine-rich fluids exsolved from highly factionated Shangshuiquan granite,which extracted and concentrated Au from the Shuiquangou complex and the Sanggan Group metamorphic rocks,and finally formed the Dongping gold deposit.
文摘In this paper, the Dongchuan type copper deposits are taken as an example to illustrate the application of GIS to the geo anomaly based delineation of mineral resources. The following eight steps are listed in this paper to delineate the permissive and preferable ore finding areas: (1) the analysis of favorable prospecting index using linear and planar geo anomalies; (2) the analysis of favorable prospecting index using combined anomalies; (3) the construction of a GIS based spatial model for mineral prognosis; (4) the delineation of the permissive ore finding area; (5) the determination of the synthetic anomalies and numerical range for the prediction of the favorable prospecting areas, and the determination of the weights of these two variables; (6) the superimposition of all the selected anomalies and the construction of the superimposition map; (7) the determination of unifying criterion of favorable prospective areas at various levels, and (8) the delineation of favorable prospective areas. Finally, this paper offers a detailed discussion of the results in the forecasting of Dongchuan type copper deposits.
