Recent studies indicate that the recycling of subducted oceanic crust is significant in the source of modern island arc magmas. It is reasonable, therefore, to assume that this process would have been equally importan...Recent studies indicate that the recycling of subducted oceanic crust is significant in the source of modern island arc magmas. It is reasonable, therefore, to assume that this process would have been equally important for the formation of arc magmas during the Phanerozic time. Unfortunately, studies on this respect are rare. This note discusses the source of granitic magma of the late Proterozoic-early Paleozoic North Qinling arc based on Pb, Nd, Sr isotopic data. The results provide evidence that the formation of the展开更多
Rare earth elements are an elemental family with special geochemical properties, and they always exist with each other in geological processes and reflect characteristically the nature of individual primitive material...Rare earth elements are an elemental family with special geochemical properties, and they always exist with each other in geological processes and reflect characteristically the nature of individual primitive material so that the REE composition patterns are展开更多
Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution through geological histor...Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution through geological history. In this paper, Early Cambrian formations in southern China are investigated. The results indicate that δ 97/95Mo values of Early Cambrian seawater may have been larger than 1.4‰, values that are close to those of the modern ocean. It was also found that the variations in Mo isotope composition in samples from two sections (Huangjiawan and Gezhongwu in Guizhou) were closely related to changes in redox conditions during sedimentary processes. Combining our results with existing data, a preliminary model for the evolution of seawater Mo isotope composition through geological history was provided. It indicated that Mo isotopic variations were generally consistent with the evolution of atmospheric oxygen.展开更多
文摘Recent studies indicate that the recycling of subducted oceanic crust is significant in the source of modern island arc magmas. It is reasonable, therefore, to assume that this process would have been equally important for the formation of arc magmas during the Phanerozic time. Unfortunately, studies on this respect are rare. This note discusses the source of granitic magma of the late Proterozoic-early Paleozoic North Qinling arc based on Pb, Nd, Sr isotopic data. The results provide evidence that the formation of the
文摘Rare earth elements are an elemental family with special geochemical properties, and they always exist with each other in geological processes and reflect characteristically the nature of individual primitive material so that the REE composition patterns are
基金Supported by the National Basic Research Program of China (Grant No. 2007 CB411402)National Natural Science Foundation of China (Grant Nos. 40773034 and 40873014)"West Light" of the Chinese Academy of Sciences,and Opening Foun-dation of State Key Laboratory of Continental Dynamics (Northwest University)
文摘Over the past decade, as one of nontraditional stable isotopes, Mo isotope has developed rapidly and now become an important geochemical proxy to trace paleo-oceanic and atmospheric evolution through geological history. In this paper, Early Cambrian formations in southern China are investigated. The results indicate that δ 97/95Mo values of Early Cambrian seawater may have been larger than 1.4‰, values that are close to those of the modern ocean. It was also found that the variations in Mo isotope composition in samples from two sections (Huangjiawan and Gezhongwu in Guizhou) were closely related to changes in redox conditions during sedimentary processes. Combining our results with existing data, a preliminary model for the evolution of seawater Mo isotope composition through geological history was provided. It indicated that Mo isotopic variations were generally consistent with the evolution of atmospheric oxygen.
