东北地区构造分区与深断裂研究——基于重力场小波多尺度分解

基于东北地区的布格重力异常资料,通过小波多尺度分解,将重力异常分解为四阶.提取主要反映深断裂的重力异常2、3阶小波细节,利用不同方向的水平梯度,计算并强化深断裂的线性特征,解译出12条深断裂,同时,结合功率谱法、东北地区地震分布、震源机制解和地质信息推断断裂的下切深度和性质,结果表明:12条深断裂分别对应拼贴地块的缝合带和对东北地区盆地群的分布与演化有着明显控制作用的岩石圈断裂两类;深断裂体系主要方向为北东、北北东向且大多为走滑断层;提取主要反映深层块体异常的3、4阶小波细节并结合深断裂体系将研究区划分为五个重力场一级分区,并首次将额尔古纳块体和兴安块体分开.五个大区分别为额尔古纳块体、兴安块体、松嫩块体、佳木斯块体和华北板块;其中兴安块体又分为二连盆地、大兴安岭两个二级分区;松嫩块体又分为小兴安岭、松辽盆地、张广才岭三个二级分区;佳木斯块体又分为那丹哈达地体、三江盆地、桦南—穆棱三个二级分区,华北板块又分为辽东半岛、华北板块、北部断裂带三个二级分区,结果表明了研究区的基本构造格局.

Research on tectonic divisions and deep faults in northeast China——based on wavelet multi-scale decomposition method

Wavelet multi-scale analysis is applied to the research on Bouguer gravity field and the explanation of tectonic structure and deep faults in northeast China.Based on Bouguer gravity anomaly,the gravity field is decomposed into four scale by multi-scale wavelet decomposition method.Extracting the second and third order details which reflect the anomalies correlated with deep faults and enhancing faults’ linear features by calculating the horizontal gradient in different directions.The results indicate 12 deep faults.Meanwhile,the paper interprets the characteristics of deep faults with the power spectrum method and the information of seism distribution,focal mechanism and geology.The result shows that 12 deep faults are divided into two types.One is the suture zone between massifs.The other plays a significant role in distribution and evolution of basin groups.Deep faults system has a predominant direction in NE,NNE and most of faults are strike-slip faults.According to the characteristics of wavelet multi-scale decomposition and the deep faults system,the paper divides the Bouguer gravity in to first-order and secondary anomaly regions and describes the characteristics of their Bouguer gravity fields.Xing’ an massif and Erguena massif was first separated.The first-order gravity anomaly regions contains Erguena massif,Xing’an massif,Songnen massif,Kiamusze massif,Huabei massif.The secondary anomaly regions contains Erlian basin,Greater Khingan region,Lesser Khingan region,Songliao basin,Zhangguangcai region,Nadanhada block,Sanjiang basin,Huanan-muling region,Liaotung peninsula region,Huabei massif,Fracture zone.The result depicts the framework of tectonic units in northeast China.