【摘要】 板内火山作用是指在远离板块构造边界的大陆内部发生的火山活动，位于中国东北的龙岗火山是研究板内火山活动的天然实验区.我们分别于2020年和2022年在吉林龙岗火山区及其周围区域连续开展大地电磁测量工作，获得了覆盖龙岗火山区的141个宽频带测点数据，通过三维反演获得了该区域地壳上地幔尺度精细的三维电性结构模型.该模型揭示出龙岗火山区及其周边地区上地壳基本上为高阻体，代表着火山区岩浆早期活动时大面积喷发冷凝所产生的火山岩.龙岗火山区下方存在着多条岩浆通道穿过莫霍面在上地幔尺度合并且向下继续延伸.这些岩浆通道自下而上可能主导了近期火山喷发和地壳隆升以及小震活动.该模型清晰的显示了一个大陆板内火山系统从地幔源到地表跨岩石圈的形成机制，结合岩石学和地球化学资料，推测龙岗火山区的岩浆系统可能直接从软流圈地幔快速上升至地壳内部减压熔融导致喷发作用.这些结果不但可以为龙岗火山区喷发风险的预测提供深层地球物理依据，也能为理解板内火山形成机制提供启发.更多还原

【Abstract】 The intraplate volcanic activity refers to the volcanic activity that occurs within the continent far from the boundary of plate tectonics.The Longgang volcano located in northeastern China is a natural experimental area for studying intraplate volcanic activity.We conducted continuous magnetotelluric surveys in the Longgang volcanic area and its surrounding areas in Jilin Province in 2020 and 2022,respectively and obtained 141 broadband measurement sites that covered the Longgang volcanic area.Through 3D inversion,we obtained a detailed 3D electrical structure model of the crust and upper mantle in the area.This model reveals that the crust in the Longgang volcanic area and its surrounding areas are a high-resistivity body,representing the volcanic rocks generated by the large-scale eruption and condensation during the early magmatic activity in the volcanic area.There are multiple magma channels beneath the Longgang volcanic area that merge and continue to extend downwards at the upper mantle scale through the Moho.These magma channels may have dominated recent volcanic eruptions,crustal uplift,and small earthquake activity.This model clearly shows the formation mechanism of a continental intraplate volcanic system across the lithosphere from the mantle source to the surface.Combined with petrology and geochemical data,it is speculated that the magma system in the Longgang volcanic area may rise rapidly from the asthenosphere mantle to the decompression melting in the crust,leading to eruption.These results can not only provide a deep geophysical basis for predicting the risk of eruption in the Longgang volcanic area but also inspire an understanding of the formation mechanism of intraplate volcanoes.更多还原