Wangtian’ e volcano, about 30 km south of Tianchi volcano is another large scale volcano center on the south slope of Changbaishan with its nearly 4 000 km^2 area of volcanic rocks distributed over the border area of...Wangtian’ e volcano, about 30 km south of Tianchi volcano is another large scale volcano center on the south slope of Changbaishan with its nearly 4 000 km^2 area of volcanic rocks distributed over the border area of the Chinese side. Based on the field occurrence, petrology and K-Ar age dating of its volcanic rocks, it can be shown that the Wangtian’e volcano had experienced two developing stages of shield forming and cone forming, while its volcanic activities can be divided into three periods: Changbai period (? —2.87 Ma), Wangtian’e period (2.69—2.41 Ma) and Hongtoushan period (2.12 Ma). Its petrographic change goes from trachybasalt→basaltic trachyandesite, trachyte→alkalic rhyolite, with a feature of bimodal volcanic rock combination similar to yet a bit different from that of Tianchi volcano, and is a new scene for study of volcanic magma evaluation of Changbaishan volcanoes.展开更多
The lower crustal xenolith of mafic two_pyroxene granulite (the majority) and hypersthene granulite in the Cenozoic basalt at Hannuoba have the characteristics of igneous blastic structure and granulite facies metamor...The lower crustal xenolith of mafic two_pyroxene granulite (the majority) and hypersthene granulite in the Cenozoic basalt at Hannuoba have the characteristics of igneous blastic structure and granulite facies metamorphic recrystallization. Study on the zircon chronology and REE geochemistry of granulite xenolith shows that the underplating of basic magma into the lower crust during late Mesozoic led to the formation of mafic accumulate, which further through metamorphism of granulite facies formed the high_density and high_velocity crustal bottom layer at the lower crust. This suggests that the underplating of mantle magma is the important way for the vertical overgrowth of continental crust since the Phanerozoic and provides new evidence for crust_mantle interaction.展开更多
文摘Wangtian’ e volcano, about 30 km south of Tianchi volcano is another large scale volcano center on the south slope of Changbaishan with its nearly 4 000 km^2 area of volcanic rocks distributed over the border area of the Chinese side. Based on the field occurrence, petrology and K-Ar age dating of its volcanic rocks, it can be shown that the Wangtian’e volcano had experienced two developing stages of shield forming and cone forming, while its volcanic activities can be divided into three periods: Changbai period (? —2.87 Ma), Wangtian’e period (2.69—2.41 Ma) and Hongtoushan period (2.12 Ma). Its petrographic change goes from trachybasalt→basaltic trachyandesite, trachyte→alkalic rhyolite, with a feature of bimodal volcanic rock combination similar to yet a bit different from that of Tianchi volcano, and is a new scene for study of volcanic magma evaluation of Changbaishan volcanoes.
文摘The lower crustal xenolith of mafic two_pyroxene granulite (the majority) and hypersthene granulite in the Cenozoic basalt at Hannuoba have the characteristics of igneous blastic structure and granulite facies metamorphic recrystallization. Study on the zircon chronology and REE geochemistry of granulite xenolith shows that the underplating of basic magma into the lower crust during late Mesozoic led to the formation of mafic accumulate, which further through metamorphism of granulite facies formed the high_density and high_velocity crustal bottom layer at the lower crust. This suggests that the underplating of mantle magma is the important way for the vertical overgrowth of continental crust since the Phanerozoic and provides new evidence for crust_mantle interaction.
