苏北盆地重力场及地壳结构特征

Gravity field and characteristics of crustal structure in Subei basin

苏北盆地作为中国东部重要的油气开发基地,近年来广泛受到学者们的关注,其以箕状凹陷为典型特征,具有"坳-断-坳"3层结构,为了对苏北盆地地壳结构做进一步分析,本文利用布格重力数据通过重力小波多尺度分解法和Parker密度界面反演法对苏北盆地的深浅部构造进行了反演,以重力小波细节为基础对苏北盆地内部次级构造单元进行了划分,并基于地震资料和深部构造特征,分析了苏北盆地的孕震环境,影响其地震活动性的主要是板块因素和断裂因素,地震主要沿构造体边界处分布.结合前人研究资料,对苏北盆地的成因机制、应力环境、深部构造进行了分析,揭示了苏北盆地莫霍面深部构造与浅部构造呈同相的关系,认为苏北盆地自中生代形成以来,除了受苏鲁造山带逆冲推覆体的控制,还受郯庐断裂带不同时期左旋及右旋运动交替变换的构造应力场的影响.

In recent years,Subei basin has been widely concerned by scholars, as an important oil and gas development base in Eastern China, which has three layers that is ＂ downwarpeddepression-downwarped＂structure,and the dustpan-shaped sunken as a typical characteristic. In order to make a further analysis on the crustal structure of the Subei basin, we used gravity data to inverting the deep and shallow structures of Subei basin through the wavelet decomposition method and Parker density interface inversion method,and made a division of the secondary tectonic units inside the Subei basin,based on the wavelet details. We also analyzed the seismic environment in Subei basin with the seismic data and deep tectonic characteristics,proving the main factors influencing the seismic activity are plate and fault,and the most of earthquakes distribute along the boundary of structures. Combining with the previous research results,we analyzed the formation mechanism,stress environment and deep tectonic structure of the Subei basin,revealing the in-phase relationship between Moho deep tectonic structure with shallow structure of Subei basin,tinking that Subei basin since Mesozoic formation,not only controlled by the thrust nappe in front of the Sulu orogenic belt,but also influenced by the stress field result from alternating left-lateral and dextrorotation tectonic movement of Tanlu fault.