The Wulong diorite porphyry displays a very unusual flower-like glomerophyric texture and is thus well-known as a gemstone type of ＂Luoyang peony stone＂ for non-geologists. Hereby, we present a comprehensive study i...The Wulong diorite porphyry displays a very unusual flower-like glomerophyric texture and is thus well-known as a gemstone type of ＂Luoyang peony stone＂ for non-geologists. Hereby, we present a comprehensive study in terms of petrography, zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotope. The rock exposed as small-scale dykes in the field, intruding in the Archean migmatized biotite- plagioclase genesis at the southern margin of the North China Craton. It exhibits typical porphyrite texture with plagioclase and amphibole as dominant and subdominant phenocrysts, respectively. The diorite porphyry rocks contain 51 wt.%-59 wt.% SiO2, belonging to medium-K calc-alkaline rock series. They are characterized by enrichment of large ion lithophile elements （LILEs, e.g., Ba） and depletion of high field-strength elements （HFSEs, e.g., Nb, Ta, Zr and Hf）, resembling island arc magmatic rocks. They show high initial Sr isotopic ratios （0.710 7-0.715 8）, low eNd（t） values （-9.9 to -13.3） and variable initial Pb isotopic ratios （206pb/204Pb vary from 17.3 to 19.3）, similar to the coeval intermediate and mafic magmatic rocks of adjacent region. These geochemical features indicate that the Wulong diorite porphyry is likely to originate from an enriched mantle with contamination of crustal materials. Zircon U-Pb dating results reveal a magma crystallization age of 480-A3 Ma, consistent with the summit of the magmatic events of the Qinling orogenic belt and reflecting the northernmost Paleozoic magmatic activity of the belt. This may indicate the influence of northward subduction of Paleotethyan oceanic slab can extend a distance of ca. 200 km to the north and reach Luoyang-Songshan region in the East Qinling Orogen.展开更多
基金the National Natural Science Foundation of China(Nos.41530211,41502046)the China Geological Survey(No.DD20160030)The Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGCJ1711)is also acknowledged for partial financially support
文摘The Wulong diorite porphyry displays a very unusual flower-like glomerophyric texture and is thus well-known as a gemstone type of ＂Luoyang peony stone＂ for non-geologists. Hereby, we present a comprehensive study in terms of petrography, zircon U-Pb geochronology, geochemistry and Sr-Nd-Pb isotope. The rock exposed as small-scale dykes in the field, intruding in the Archean migmatized biotite- plagioclase genesis at the southern margin of the North China Craton. It exhibits typical porphyrite texture with plagioclase and amphibole as dominant and subdominant phenocrysts, respectively. The diorite porphyry rocks contain 51 wt.%-59 wt.% SiO2, belonging to medium-K calc-alkaline rock series. They are characterized by enrichment of large ion lithophile elements （LILEs, e.g., Ba） and depletion of high field-strength elements （HFSEs, e.g., Nb, Ta, Zr and Hf）, resembling island arc magmatic rocks. They show high initial Sr isotopic ratios （0.710 7-0.715 8）, low eNd（t） values （-9.9 to -13.3） and variable initial Pb isotopic ratios （206pb/204Pb vary from 17.3 to 19.3）, similar to the coeval intermediate and mafic magmatic rocks of adjacent region. These geochemical features indicate that the Wulong diorite porphyry is likely to originate from an enriched mantle with contamination of crustal materials. Zircon U-Pb dating results reveal a magma crystallization age of 480-A3 Ma, consistent with the summit of the magmatic events of the Qinling orogenic belt and reflecting the northernmost Paleozoic magmatic activity of the belt. This may indicate the influence of northward subduction of Paleotethyan oceanic slab can extend a distance of ca. 200 km to the north and reach Luoyang-Songshan region in the East Qinling Orogen.
