The Shushui Complex can be divided into three rock units based on field investigation,petrography and geochemistry:(1)felsic gneisses,(2)supracrustal rocks consisting of amphibolite,marble and quartzited,and(3)late gr...The Shushui Complex can be divided into three rock units based on field investigation,petrography and geochemistry:(1)felsic gneisses,(2)supracrustal rocks consisting of amphibolite,marble and quartzited,and(3)late granites.Of the complex,felsic gneisses are dominant and formed in the Late Archaean,which were intruded by a basic dyke with a whole-rock Rb-Sr isochron age of 2264±219Ma.The data on rare-earth elements as well as on major and trace elements presented for most of the rock trpes making up the complex suggest that(1)basic gneisses were produced by partial melting of mantle peridotite,followed by fractional crystallization ,and (2)felsic gneisses produced by varying degree of melting of a mafic source.The most suitable tectonic setting to account for the generation of both types would be similar to the underplate setting.展开更多
The 2.34 cm-wide garnet porphyroblast in the Paleoproterozoic felsic granulite from the Huangtuling area, North Dabieshan, has been reinvestigated for compositional variation in light of Ca-composition X-ray mapping t...The 2.34 cm-wide garnet porphyroblast in the Paleoproterozoic felsic granulite from the Huangtuling area, North Dabieshan, has been reinvestigated for compositional variation in light of Ca-composition X-ray mapping to obtain peak P-T conditions of granulite-facies metamorphism. A new core-rim traverse was conducted through where there is little influence on Ca-profile and slight modification in Mn-, Mg- and Fe-profiles with the highest Mg/(Mg+Fe) value of 0.467. Reasonable peak P-T conditions were estimated to be 1.50-1.70 GPa and 1 100-1 150 ℃ according to TWQ-based garnet-Al-orthopyroxene thermobarometry. These estimations suggest that the Huangtuling granulite once was subjected to ultrahigh-temperature (UHT) granulite-facies metamorphism following a high-pressure granulite-faices metamorphic stage, implying that a deep subduction and collision process relevant to the Yangtze block occurred in the Paleoproterozoic time, probably as a response to the global assembly event of the Columbia supercontinent.展开更多
文摘The Shushui Complex can be divided into three rock units based on field investigation,petrography and geochemistry:(1)felsic gneisses,(2)supracrustal rocks consisting of amphibolite,marble and quartzited,and(3)late granites.Of the complex,felsic gneisses are dominant and formed in the Late Archaean,which were intruded by a basic dyke with a whole-rock Rb-Sr isochron age of 2264±219Ma.The data on rare-earth elements as well as on major and trace elements presented for most of the rock trpes making up the complex suggest that(1)basic gneisses were produced by partial melting of mantle peridotite,followed by fractional crystallization ,and (2)felsic gneisses produced by varying degree of melting of a mafic source.The most suitable tectonic setting to account for the generation of both types would be similar to the underplate setting.
基金This paper is supported by the Special Doctoral Grant of the Ministry ofEducation of China(No.98049114)and the National Natural Science Foundation of China(No.49972023).
文摘The 2.34 cm-wide garnet porphyroblast in the Paleoproterozoic felsic granulite from the Huangtuling area, North Dabieshan, has been reinvestigated for compositional variation in light of Ca-composition X-ray mapping to obtain peak P-T conditions of granulite-facies metamorphism. A new core-rim traverse was conducted through where there is little influence on Ca-profile and slight modification in Mn-, Mg- and Fe-profiles with the highest Mg/(Mg+Fe) value of 0.467. Reasonable peak P-T conditions were estimated to be 1.50-1.70 GPa and 1 100-1 150 ℃ according to TWQ-based garnet-Al-orthopyroxene thermobarometry. These estimations suggest that the Huangtuling granulite once was subjected to ultrahigh-temperature (UHT) granulite-facies metamorphism following a high-pressure granulite-faices metamorphic stage, implying that a deep subduction and collision process relevant to the Yangtze block occurred in the Paleoproterozoic time, probably as a response to the global assembly event of the Columbia supercontinent.
