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
1.Objectives The Tiechang tin deposit is located in the northern part of the Baoshan Terrane of the Sanjiang Tethys Orogeny in western Yunnan Province of China.Tiechang tin deposit mainly occurs in the migmatite accom...1.Objectives The Tiechang tin deposit is located in the northern part of the Baoshan Terrane of the Sanjiang Tethys Orogeny in western Yunnan Province of China.Tiechang tin deposit mainly occurs in the migmatite accompany with the structural fracture zone,and only a few of them occur in the internal contact zone between metamorphic rock and migmatite or in the interlayer fracture zone in metamorphic rock(Fig.1;Lei YA et al.,2013).Different from most tin deposits(such as Lailishan deposit at 47 Ma;Xiaolonghe deposit at 71 Ma;Tieyaoshan deposit at 119 Ma;Chen XC et al.,2014)in western Yunnan,the mineralization of Tiechang tin deposit occured in Oligocene.Therefore,the metallogenic chronology of tin deposits in western Yunnan needs to be further improved.In this paper,the authors use the cassiterite U-Pb LA-ICP-MS method to determine the metallogenic age of the Tiechang tin deposit.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.
基金supported by the National Key Research and Development Program of China(2018YFC0603704)project of the China Geological Survey(DD20190166,DD20190159).
文摘1.Objectives The Tiechang tin deposit is located in the northern part of the Baoshan Terrane of the Sanjiang Tethys Orogeny in western Yunnan Province of China.Tiechang tin deposit mainly occurs in the migmatite accompany with the structural fracture zone,and only a few of them occur in the internal contact zone between metamorphic rock and migmatite or in the interlayer fracture zone in metamorphic rock(Fig.1;Lei YA et al.,2013).Different from most tin deposits(such as Lailishan deposit at 47 Ma;Xiaolonghe deposit at 71 Ma;Tieyaoshan deposit at 119 Ma;Chen XC et al.,2014)in western Yunnan,the mineralization of Tiechang tin deposit occured in Oligocene.Therefore,the metallogenic chronology of tin deposits in western Yunnan needs to be further improved.In this paper,the authors use the cassiterite U-Pb LA-ICP-MS method to determine the metallogenic age of the Tiechang tin deposit.
