中国东北地区新生代火山活动的构造背景

中国东北地区新生代以玄武岩为主的喷发经历了60~29 Ma、25~15 Ma、＜2 Ma三期及不同喷发期之间的过渡阶段，而每一期又可以分为若干旋回。火山作用形成于不同的构造部位，沿断裂和非断裂分布的玄武岩均有存在，且与不同时期的大陆边缘构造演化相匹配。不同的构造背景下火山活动的分布也不同，且具明显的迁移性。构造环境体现为非造山大陆边缘张裂隙、上地幔上隆的陆内拉张环境、陆内非造山环境等特征。上新世晚期—更新世以来的火山活动与中国西南部地区的大陆板块间的碰撞作用没有关系。

Tectonic Settings of Cenozoic Volcanism in Northeastern China

The basaltic eruptions experienced three stages in the Cenozoic in northeastern Chin a, which are 60~29 Ma, 25~15 Ma and later than 2 Ma and every stage can be di vided into several erupting cycles, as well as eruptions in an interval between stages. The volcanism was active along faults or in som e atectonic settings. The volcano eruptions developed at different tectonic posi tions, accompanied by tectonic evolution on th e continent al margin in various periods. In different tectonic settings, the distribution of volcanoes is inconsistent and shows notable migration characteristics such as with NWW trends. The tectonic settings are characterized by extensional fra ctures on the continental margin, intracontinental extension controll ed by the upper mantle upwelling, and intracontinental non orogenic sett ing. The L ate Pliocene-Holocene volcano eruptions were not related with the collision of t he India-Eurasian plates in southwestern China.