The samples of ductile-rheologic deformational augen granite from the Yunkai uplift area, western Guangdong province, were determined by the whole-rock Sm-Nd, Pb-Pb and Rb-Sr isotopic dating to have an Sm-Nd isochron ...The samples of ductile-rheologic deformational augen granite from the Yunkai uplift area, western Guangdong province, were determined by the whole-rock Sm-Nd, Pb-Pb and Rb-Sr isotopic dating to have an Sm-Nd isochron age of 1414±68 Ma, a Pb-Pb isochron age of 1388±90 Ma and a Rb-Sr isochron age of 490±36 Ma. The first two ages are interpreted as the formation age of this suite of granite and the last age represents the timing of the tectono-thermal event of Caledonian ductile-rheologic shear partial melting. It is indicated that in the study area not only an orogeny took place in the Caledonian, but also a more important tectono-magmatic activity occurred in the Meso-proterozoic there, which may be related to the subduction-collision between the Yangtze block and Cathaysia block.展开更多
The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located...The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located in the western part of Yunkai Area, with an abundance of Pubei batholiths. Zircon U–Pb geochronology of Pubei batholiths shows that crystallization age ranges from 251.9 ± 2.2 to 244.3 ± 1.8 Ma, thus belonging to Indosinian orogeny. Geochemistry and Sr isotopic compositions of the Pubei batholiths show that it is derived from the partial melting of large scale crustal melting during the stage of exhumation and uplifting of the lower-middle crust. In addition, strontium isotope of sphalerite from the Xinhua Pb–Zn–(Ag) deposit, has limited ranges in ^(87)Rb/^(86)Sr and ^(87)Sr/^(86)Sr, ranging from 0.4077 to 1.0449, and 0.718720 to 0.725245, respectively. The initial ^(87)Sr/^(86)Sr ratios of sphalerite ranges between 0.718720 and 0.725245, which is higher than that of upper continental crust and lower than that of the Pubei batholiths, illustrating the fluid might be derived from the mixing of Pubei pluton and upper continental crust.展开更多
There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo...There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo deposits. In this study, we obtained zircon U-Pb ages of the ore-bearing biotite granites and their mafic enclaves from 884-1 to 1104-1 Ma. Zircons from the granites show Hf isotopic compositions with negative C-Hf（t） values of -5.9 to -0.6 and calculated Hf model ages （TvM2） of 1.5-1.2 Ga; indicating that the Middle Proterozoic crustal materials may have provided an important source for the magmatic rocks in this district during the Late Yanshanian Period, whereas zircons from the mafic enclaves show positive era（t） values of 1.3 to 10.1 with younger Hf model ages （TDM2） of 0.5-1.1 Ga, suggesting a mantle component may have involved in the granitic magma generation. Sulfur isotope study of the sulfide minerals from the W-Mo deposits show a narrow 834S distribution with most data ranging from -4.2%0 to 5.2‰. In addition, this study reports the first Fe isotopic compositions of pyrite in the W-Mo deposits, which show a uniform distribution range with the values near zero （656Fe=0.16‰-0.58‰, average 0.35‰; 657Fe=0.02‰-0.54‰, average 0.48‰）. These data indicate that the ore-forming materials may come from the deep-sourced granitic magma, and the mineralizations show a close relationship with the granitic magmatism during the Late Yanshanian Period. Combining with previous results, we suggest that there is a widespread porphyry-skarn W-Mo mineralization in the Yunkai area during the Late Cretaceous （80-110 Ma）, which has a close relationship with the Late Yanshanian magmatism that may have formed during the rollback of the subducted Pacific Plate.展开更多
基金This study was financially supported by the NationalNatural Science Foundation of China grant 49502036；the key project (95-02-007) of Science and Technology of the Ninth Five-Year Plan of the Ministry of Geology and Mineral Resources.
文摘The samples of ductile-rheologic deformational augen granite from the Yunkai uplift area, western Guangdong province, were determined by the whole-rock Sm-Nd, Pb-Pb and Rb-Sr isotopic dating to have an Sm-Nd isochron age of 1414±68 Ma, a Pb-Pb isochron age of 1388±90 Ma and a Rb-Sr isochron age of 490±36 Ma. The first two ages are interpreted as the formation age of this suite of granite and the last age represents the timing of the tectono-thermal event of Caledonian ductile-rheologic shear partial melting. It is indicated that in the study area not only an orogeny took place in the Caledonian, but also a more important tectono-magmatic activity occurred in the Meso-proterozoic there, which may be related to the subduction-collision between the Yangtze block and Cathaysia block.
基金supported by grants by the National Natural Science Foundation of China (No.41272097)the China Geological Survey Project (No.12120114016601)+1 种基金the Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences (Wuhan) (No.CUG120702)the Teaching Laboratory Foundation of China University of Geosciences (Wuhan) (No.SKJ2013085,SKJ2014010)
文摘The Yunkai Area is located at the southern South China Block and is part of the Qinzhou Bay-Hangzhou Bay Metallogenic Belt, which is a famous polymetallic mineralization belt. The Xinhua Pb–Zn–(Ag)deposit is located in the western part of Yunkai Area, with an abundance of Pubei batholiths. Zircon U–Pb geochronology of Pubei batholiths shows that crystallization age ranges from 251.9 ± 2.2 to 244.3 ± 1.8 Ma, thus belonging to Indosinian orogeny. Geochemistry and Sr isotopic compositions of the Pubei batholiths show that it is derived from the partial melting of large scale crustal melting during the stage of exhumation and uplifting of the lower-middle crust. In addition, strontium isotope of sphalerite from the Xinhua Pb–Zn–(Ag) deposit, has limited ranges in ^(87)Rb/^(86)Sr and ^(87)Sr/^(86)Sr, ranging from 0.4077 to 1.0449, and 0.718720 to 0.725245, respectively. The initial ^(87)Sr/^(86)Sr ratios of sphalerite ranges between 0.718720 and 0.725245, which is higher than that of upper continental crust and lower than that of the Pubei batholiths, illustrating the fluid might be derived from the mixing of Pubei pluton and upper continental crust.
基金supported by the Fundamental Research Funds for the Central Universities (No. CUG120702)
文摘There are a wide range of magmatism and mineralization in the Yunkai area of South China during the Late Yanshanian Period, including the newly discovered Michang, Youmapo, Sanchaehong and Songwang porphyry-skarn W-Mo deposits. In this study, we obtained zircon U-Pb ages of the ore-bearing biotite granites and their mafic enclaves from 884-1 to 1104-1 Ma. Zircons from the granites show Hf isotopic compositions with negative C-Hf（t） values of -5.9 to -0.6 and calculated Hf model ages （TvM2） of 1.5-1.2 Ga; indicating that the Middle Proterozoic crustal materials may have provided an important source for the magmatic rocks in this district during the Late Yanshanian Period, whereas zircons from the mafic enclaves show positive era（t） values of 1.3 to 10.1 with younger Hf model ages （TDM2） of 0.5-1.1 Ga, suggesting a mantle component may have involved in the granitic magma generation. Sulfur isotope study of the sulfide minerals from the W-Mo deposits show a narrow 834S distribution with most data ranging from -4.2%0 to 5.2‰. In addition, this study reports the first Fe isotopic compositions of pyrite in the W-Mo deposits, which show a uniform distribution range with the values near zero （656Fe=0.16‰-0.58‰, average 0.35‰; 657Fe=0.02‰-0.54‰, average 0.48‰）. These data indicate that the ore-forming materials may come from the deep-sourced granitic magma, and the mineralizations show a close relationship with the granitic magmatism during the Late Yanshanian Period. Combining with previous results, we suggest that there is a widespread porphyry-skarn W-Mo mineralization in the Yunkai area during the Late Cretaceous （80-110 Ma）, which has a close relationship with the Late Yanshanian magmatism that may have formed during the rollback of the subducted Pacific Plate.
