Neoproterozoic magmatic rocks are widespread in the western margin of the Yangtze block, and their origin and genesis have significant implications for understanding the evolution of the Rodinia super- continent. However, there are currently two opposing interpretations for their petrogenesis and tectonic setting: mantle plume-related and island arc origin. To further verify these two competing models, SHRIMP U-Pb zircon age determinations and geochemical and Nd-Hf isotopic analyses are conducted on the mafic dykes in the Kangdian Rift, western Sichuan. U-Pb dating suggests that these mafic dykes were emplaced at 780―760 Ma, spatially and temporally coeval with the Kangding granitoid complex. The parental magmas of these dykes were derived from a depleted asthenosphere mantle source likely triggered by an anomalously-hot mantle plume. Despite some arc-geochemical features caused by variable degrees of contamination of young island arc crust during magma ascending and emplace- ment, they show general geochemical and Nd-Hf isotopic features similar to those of the intraplate basalts. Our results support the reconstruction model of Rodinia in which the South China block was located between Australia and Laurentia. 相似文献
Seaweeds cultivation has resulted in great achievements, although it has a history of only a few decades. With higher productivity and resulting higher profit, it has become the leading marine exploitation industry with the brightest prospects. The relatively limited species introduced for commercial cultivation showed great biological diversity. Introduction of selected good strains for traditional cultivation and the transformation from cultivation of mixed strains to that of pure cell lines are two certain tendencies in the future. Pure line cultivation of seaweeds in a sort of advanced biotechnology. It provides new opportunities for not only the industry itself, but also the stable market of high quality natural marine products. More work should be done on principles and methods to obtain optimal results from the combination of pure line cultivation techniques with advanced biochemistry. The programmed batch production of fine chemicals such as polysaccharides and proteins will probably become the social demand.
