基于重磁场的延边微板块地壳结构特征研究

延边地区位于多个微板块的结合部位,区内发育长白山活动火山群,地震活动频繁。本文通过重磁小波多尺度分解与莫霍面、居里面深度反演分析,研究延边地区的微板块地壳结构特征。其中敦化-密山断裂以东的胶辽地块地壳厚度最大,约38~40km,兴凯地块则最小,约34~36km,敦化-密山断裂以西的松嫩地块地壳厚度变化平缓,约36~37km;NE向敦化-密山断裂为延边地区的一级断裂,切穿莫霍面,为松嫩地块的东侧边界;NW向展布的富尔河-红旗河断裂、秋梨沟老头沟断裂与汪清-敬信断裂则属于胶辽地块与兴凯地块之间的缝合带,控制居里面分区及形态,而居里面隆起区及其边缘则多分布火山口,表明居里面的局部隆起与岩浆活动关系密切。

Using Gravity and Magnetic Data to Study the Crustal Structure Characteristics of Microplates in Yanbian, Jilin, China

The Yanbian region is located in the conjunction area of the Songnen, Jiaoliao and Xingkai microplates with the Changbaishan active volcanoes and frequent earthquakes. Using the multi scale wavelet decomposition and the Parker inversion analysis, this study analyzed the crustal structure and microplate characteristics of the Yanbian region. The results show that the Jiao Liao microplate in the east of the Dunhua Mishan Fault has the largest crustal thickness up to 38~40 km in the Yanbian area, the Xingkai microplate has the least thickness of 36~37 km, and the Songnen microplate in the west of the Duhua Mishan Fault has an average thickness ranging 36~37km. The first order fault in the Yanbian Area, the NE trending Dunhua Mishan fault which penetrates to the depth of Moho, is the eastern boundary of the Songnen microplate. The NW trending Fuerhe Hongqihe fault, Qiuligou Laotougou fault and Wangqing Jingxin fault are the tectonic boundaries between the Jiaoliao microplate and the Xingkai microplate, which also control the distribution of the Curie depth. The Curie depth distribution of the Yanbian area is similar with that of the Moho depth, but some local uplift areas of the Curie are correlated with the distribution of the active volcanoes, indicating that the uplift of the Curie may link with the magmatic activities in the Yanbian area.