中国南海重力梯度多尺度分析

Multi-scale analysis of gravity gradients in South China Sea

针对鲜有学者利用沿轨重力梯度数据研究中国南海地下结构的问题,该文采用小波多尺度分析方法和功率谱估计方法对该地区重力梯度数据进行处理,以获取不同深度结构特征。该方法从重力梯度数据中有效提取出不同深度场源所产生的重力信号,提升了重力梯度数据的垂向识别能力,可以给出地下介质在不同深度的分布状况。研究结果表明:浅层场源所产生的重力梯度在区域中部和东南角分布密集,呈现正负异常交替出现的链状分布特征;在平均深度约31 km处的地下存在一个被高密度体所包围的大型低密度体;45 km以下的深层区域,未有明显异常体显示,密度分布总体上沿西北-东南方向逐渐增大。

Aiming at present situation that few scholars have investigated the subsurface structure of South China Sea using the on-orbit gravity gradients,in this paper the on-orbit gravity gradients of study area are processed by wavelet multi-scale analysis and power spectrum estimation to study the tectonic structure at different depths.This method can extract the gravity signals caused by various sources at different depths from gravity gradients,which improves the vertical recognition ability of gravity data and can also show the mass distribution at different depths.The research results indicate that:The gravity gradients produced by shallow field sources are distributed intensively in the middle and southeast corner of the region,showing chain distribution characteristics of positive and negative anomalies alternately;there is a large low-density body surrounded by high-density body at the depth of about 31 km;there is no obvious abnormal body in the deep area below 45 km,and the density distribution increases gradually along the northwest southeast direction.