中国东北地区中生代火山岩的大地构造意义

TECTONIC SIGNIFICANCE OF MESOZOIC VOLCANIC ROCKS IN NORTHEASTERN CHINA

中国东北地区中生代火山岩可划分为西部大兴安岭环状火山岩带、南部火山岩带和东部火山岩带，它们是古亚洲洋构造域向太平洋构造域转换时期不同构造环境的产物。西部大兴安岭环状火山岩带的形成与古亚洲洋闭合过程中壳幔相互作用引起的深部热地幔柱的上升有关，南部火山岩带与构造域转换时期走滑拉伸构造有关，而东部火山岩带则是太平洋板块斜向俯冲作用的产物。

Mesozoic volcanic rocks in Northeastern China can be classified into three volcanic belts,i.e. Western Daxinganling ring like volcanic belt,Southern volcanic belt,and Eastern volcanic belt.They were formed in different tectonic settings during the transforming period of the tectonic regime from the Paleo Asian to Pacific.Younging from outer to inner part,the Daxinganling ring like volcanic belt shows a kind of structure of “thermal synclin”,the areal and ring like distribution,and the geochemical features of highly enriched lithophile elements suggest that the formation of this belt is related to the rising of enriched hot mantle plume that was induced by the reaction between the oceanic lithosphere and the continental mantle during the closing process of Paleo Asian Ocean.Located at the eastern part of the Indosinian Early Yanshanian tectonic belt in the northern margin of the Northern China Platform,the NEE Southern volcanic belt is the product of lithospheric extension during the transforming period of tectonic domain from Triassic to Early Cretaceous,accompanied by the horizontal development of Mongolian Permian Triassic hot mantle plume and the continental dispersion.As the inner part of NEE calc alkaline volcanic belt along the continental margin of Eastern Asia,the Eastern volcanic belt belongs to the Late Jurassic Early Cretaceous calc alkaline volcanic belt from Okhotsk,Sikhote Alin to northeastern Japan,and is related to tha oblique subduction of the Farralon Izanagi and Kula Pacific oceanic ridges at the Eastern continental marging.