On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of ...On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of the regional structures, volcanic structures and products of volcanic activity in the coastal area ofsoutheastern Zhejiang. On the basis and through a systematic comparison of the products of magmatism in thearea, it is considered that there exists a compsite volcanic structural belt composed of linear and circular struc-tures and it has been demonstrated that there exist volcanic intrusive complexes--'trinity' composed of vol-canic, subvolcanic and plutonic rocks. It is suggested that the volcanic intrusive complexes in the area belong tothe typical syntexis series and that its materials were derived from a mixed source of crust and mantle.展开更多
The thermal history of the late Mesozoic miarolitic granite has been studied based on zircon U-Pb dating, whole rock Rb-Sr dating and K-Ar dating of muscovite, biotite and K-feldspar from the same rock sample. From th...The thermal history of the late Mesozoic miarolitic granite has been studied based on zircon U-Pb dating, whole rock Rb-Sr dating and K-Ar dating of muscovite, biotite and K-feldspar from the same rock sample. From the beginning of zircon crystallization to the closure of K-Ar system of biotite, the granite body had a slow cooling rate (11.0℃/Ma) and an ascending rate (0.07 mm/a). From the end of this stage to the closure of K-Ar system of K-feldspar, the granite body increased its cooling rate (45℃/Ma) and ascending rate (0.36 mm/a). The thermal history of the Xincun granite with a slow cooling rate at the early stage and a fast cooling rate at the late stage may have been related to the fact that the Fujian coastal area had very high geothermal gradient in the late Mesozoic and evident decrease in geothermal gradient in the early Cenozoic.展开更多
The Laoshan A-type granite is a highly evolved granite body. The study on accessoryminerals indicates that there exist differentiation and accumulation of fluids during the late stage of evolution of the granite. The ...The Laoshan A-type granite is a highly evolved granite body. The study on accessoryminerals indicates that there exist differentiation and accumulation of fluids during the late stage of evolution of the granite. The released fluids are rich in rare-earth elements (REE), high-field-strength elements (HFSE, such as Nb, Ta, Zr, Hf, Th, U, and Y) and volatiles (F, P, CO2, etc.). Owing to the presence of fluid, accessory mineral assemblages have changed during the evolution of A-type granite, and are especially characterized by large amounts of independent REE-Nb-Y-Th minerals present in the late facies. Late-accumulation of fluids may be of the general feature of A-type granites, at least of highly evolved ones.展开更多
文摘On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of the regional structures, volcanic structures and products of volcanic activity in the coastal area ofsoutheastern Zhejiang. On the basis and through a systematic comparison of the products of magmatism in thearea, it is considered that there exists a compsite volcanic structural belt composed of linear and circular struc-tures and it has been demonstrated that there exist volcanic intrusive complexes--'trinity' composed of vol-canic, subvolcanic and plutonic rocks. It is suggested that the volcanic intrusive complexes in the area belong tothe typical syntexis series and that its materials were derived from a mixed source of crust and mantle.
文摘The thermal history of the late Mesozoic miarolitic granite has been studied based on zircon U-Pb dating, whole rock Rb-Sr dating and K-Ar dating of muscovite, biotite and K-feldspar from the same rock sample. From the beginning of zircon crystallization to the closure of K-Ar system of biotite, the granite body had a slow cooling rate (11.0℃/Ma) and an ascending rate (0.07 mm/a). From the end of this stage to the closure of K-Ar system of K-feldspar, the granite body increased its cooling rate (45℃/Ma) and ascending rate (0.36 mm/a). The thermal history of the Xincun granite with a slow cooling rate at the early stage and a fast cooling rate at the late stage may have been related to the fact that the Fujian coastal area had very high geothermal gradient in the late Mesozoic and evident decrease in geothermal gradient in the early Cenozoic.
文摘The Laoshan A-type granite is a highly evolved granite body. The study on accessoryminerals indicates that there exist differentiation and accumulation of fluids during the late stage of evolution of the granite. The released fluids are rich in rare-earth elements (REE), high-field-strength elements (HFSE, such as Nb, Ta, Zr, Hf, Th, U, and Y) and volatiles (F, P, CO2, etc.). Owing to the presence of fluid, accessory mineral assemblages have changed during the evolution of A-type granite, and are especially characterized by large amounts of independent REE-Nb-Y-Th minerals present in the late facies. Late-accumulation of fluids may be of the general feature of A-type granites, at least of highly evolved ones.
