龙岗地块-辽吉裂谷深部电性结构特征  

Deep structural characteristics of the Longgang block and Liaoji rift

作　　者：姚大为[1,2] YAO Dawei(Institute of Geophysical and Geochemical Exploration,CAGS,Langfang 065000,China;Laboratory of Geophysical EM Probing Technologies,MLR,Langfang 065000,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000 [2]自然资源部地球物理电磁法探测技术重点实验室,廊坊065000

出　　处：《物探化探计算技术》2022年第2期245-250,共6页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：中央公益性基本科研业务费基金(1212011220258)。

摘　　要：在辽东-吉南成矿带布设一条长150 km,横穿龙岗地块和辽吉裂谷的大地电磁测深观测剖面,对龙岗地块和辽吉裂谷深部电性结构进行探测研究。针对研究区内强电磁干扰,对部份测点原始数据采用了Hilbert Huang变换来压制干扰;针对测深曲线具有明显走势特征的测点,应用层状介质电阻率与相位互算技术进行处理,获取了研究区内质量较为可靠的大地电磁数据。二维反演采用非线性共轭梯度法(NLCG),该方法是最光滑模型约束的反演,能实现对最小构造分辨。结合区域地质资料,最终得到剖面的二维电性结构。研究结果表明:龙岗地块太古代基底受逆冲推覆构造及走滑断裂影响,太古代基底顶面呈断块状起伏,基底埋深变化较大,基底埋深一般小于5 km;龙岗地块和辽吉裂谷之间存在一个明显的东南倾的构造界面(辽吉裂谷北缘斜坡),斜坡两侧存在明显的电性差异;辽吉裂谷褶皱构造发育,太古代结晶基底因后期改造而缺失,以辽吉花岗岩为结晶基底,埋深可达10 km以上。Two-dimensional magnetotelluric observation section with 150 km length across the Longgang block and Liaoning Jilin rift is conducted in Eastern Liaoning and Southern Jilin mineralization with the emplacement.For the strong electromagnetic interference,Hilbert Huang transform of the magnetotelluric sounding data was used to process technology to suppress interference on the part of the measuring point of the original data;for sounding curve with obvious characteristics of the trend of measured points and application of layered medium resistivity and phase mutual calculation technique,more reliable magnetotelluric data with high quality were obtained.The 2D inversion is a nonlinear conjugate gradient method(NLCG),which is the most smooth model constrained inversion.Combined with regional geological data,the two-dimensional structure of the section is obtained.The results show that:the Longgang block is a ancient basement with thrust nappe structure and strike slip fault.Archean basement top surface fault block of ups and downs,buried depth of basement changes larger,basement was buried deep and usually less than 5km;Longgang block and Liaoning Jilin rift between a southeast dipping structure interface.Liao Ji rift in the northern slope,slopes on both sides of the exist significant difference;The fold structure development of Liao Ji rift is too ancient crystalline basement for later modification and deletion,and its granites are considered as the crystalline basement,buried deep reach more than 10 km.

关 键 词：MT 电性结构 龙岗地块 辽吉裂谷 

分 类 号：P631.3[天文地球—地质矿产勘探]