联合气枪震源体波和面波反演长江中下游上地壳高精度速度结构

长江中下游是我国重要的铁铜金多金属成矿带，精细速度结构对分析成矿机制以及断裂带对成矿系统的控制作用具有重要指导意义。然而受限于观测数据分布和研究方法对震相信息的利用，该区域上地壳三维速度成像精度仍有待提高。2015年开展的长江实验（20个固定及1872个走航流动气枪密集激发和602个台站接收）为研究该区域结构特征提供了丰富的数据，其中气枪150m间隔走航激发的信号可有效提高成像精度但尚未被利用。为此，本项目将开展以下研究：（1）发展强背景噪声下微弱信号提取方法，提高气枪走航激发信号的信噪比；（2）联合气枪不同周期的面波频散数据和体波走时信息进行反演成像，获得长江中下游上地壳高精度三维Vp和Vs速度结构；（3）分析速度结构与成矿带及断裂带的关系，探索矿集区的范围和分布特征。本项研究对区域地质构造特征分析和矿产资源普查等具有重要意义，并有望为今后人工震源成像工作提供新的技术方法。

The Middle-Lower Yangtze River is an important iron-copper-gold polymetallic metallogenic belt in China, the fine velocity structure has important guiding significance to analyze the mineralization mechanism and the control effect of the fault zone on the mineralization system. Limited by the distribution of observational data and different research methods, the three-dimensional imaging accuracy of the upper crust in this area still needs to be improved. The Yangtze River experiment carried out in 2015 (airgun excitation of 20 fixed and 1872 mobile shooting sites and recorded at 602 observation stations) provided rich data for studying the structural characteristics of this region. In these data, the airgun signals excited at mobile shooting sites (with 150m intervals) can effectively improve the imaging accuracy but has not yet been utilized. Therefore, we plan to carry out the following research in this project: (1) Develop a weak signal extraction method under strong ambient noise to improve the signal-to-noise ratio of the airgun signals excited in the walkway. (2) Joint inversion of body wave travel time and surface wave dispersion data in different periods to obtain the high resolution upper crustal Vp and Vs structures beneath the Middle-Lower Yangtze River; (3) Analyze the relationship between velocity structure and metallogenic belt and fault zone, and explore the scope and distribution characteristics of the ore concentration areas. This research is of great significance for the analysis of regional geological structure characteristics and the general survey of mineral resources, etc., and can provide new tomography method for future study using artificial source.