| 重震反演中国东北地壳上地幔三维密度结构 |
| |
| 引用本文： | 索奎,张贵宾,江国明,徐峣.重震反演中国东北地壳上地幔三维密度结构[J].地球物理学报,2015,58(7):2436-2444. |
| |
| 作者姓名： | 索奎 张贵宾 江国明 徐峣 |
| |
| 作者单位： | 中国地质大学(北京)地球物理与信息技术学院, 北京 100083 |
| |
| 基金项目： | 国家高技术发展研究"863计划"课题(2011AA060501),国土资源部专项"深部探测技术实验与集成"(SinoProbe-02-05)联合资助. |
| |
| 摘 要： | 本文利用重力和地震P波到时数据反演得到了中国东北地区地壳上地幔三维密度结构.与单一的重力或地震反演相比,重震反演一方面有效地克服了重力反演结果垂向分辨率低的问题,另一方面也提高了地震反演结果的可靠性.结果显示:中国东北地区的地壳及上地幔剩余密度异常分布与构造单元具有明显的相关性,造山带对应低密度异常,盆地对应高密度异常;区域内火山下方有明显的低密度体存在,可能是由于太平洋板块俯冲进入上地幔并部分滞留,在滞留板块深部脱水和软流圈热物质共同作用下产生了上涌岩浆,喷发后形成了火山.
|
| 关 键 词： | 联合反演 重力数据 地震层析成像 密度结构 中国东北 |
| 收稿时间： | 2015-01-09 |
3-D density distribution of the crust and upper mantle beneath Northeast China by joint inversion of gravity and seismic data |
| |
| SUO Kui,ZHANG Gui-Bin,JIANG Guo-Ming,XU Yao.3-D density distribution of the crust and upper mantle beneath Northeast China by joint inversion of gravity and seismic data[J].Chinese Journal of Geophysics,2015,58(7):2436-2444. |
| |
| Authors: | SUO Kui ZHANG Gui-Bin JIANG Guo-Ming XU Yao |
| |
| Institution: | School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China |
| |
| Abstract: | The Northeast China plate is composed of multiple micro-plates, so its geological structure is very complicated and there exist lots of fault zones. Although some investigations have been done in this area, less effort has been devoted to its three-dimensional (3-D) density structure that plays an important role in dividing tectonic unit and studying the evolution of this plate.In this study, considering the high lateral resolution of the gravity data and the vertical resolution of seismic tomography, we used both the gravity data and P-wave arrival time data to obtain the three-dimensional density structure of the crust and the upper mantle beneath the Northeast China area. We firstly obtained a 3-D P-wave velocity model at depths between 0 and 560 km by using the seismic tomography method and 12429 P-wave arrival time data. Based on the relationship between seismic velocity and density, the obtained velocity model is then converted to a density model that can be used as the initial model in the gravity inversion. Then we calculate the anomaly field generated by the lower boundary of deposition, the Moho and the deep formation. When these calculated fields are removed from the Bouguer gravity anomaly, the 5'× 5' residual gravity anomaly field can be used to invert for the 3-D residual density distribution. The density structure is finally converted to the velocity structure that is used as the initial model for the next seismic tomography. This process is repeated for several times until the density changes are small enough. As a result, we get the distribution of residual density at 9 different depths of 10 km, 30 km, 60 km, 100 km, 150 km, 210 km, 300 km, 400 km, and 500 km.The results show that (1) the joint inversion effectively not only improves the vertical resolution of gravity inversion but also stabilizes the seismic inversion results relative to the independent inversions by using only gravity or seismic data; and (2) the distribution of residual density anomalies in the crust and the upper mantle beneath the Northeast China area seems to be correlated with the tectonic units, in which the lower density anomalies correspond well to the orogenic belts while high density anomalies are related to the basins; and (3) a distinct lower density body exists beneath the volcanoes in this study area.Due to the seismic inversion result as the prior information, the vertical resolution of the density distribution is enhanced largely. The lower density anomalies associated with the orogenic belts and faults zones may be caused by the presence of magmatic rocks, and the higher ones associated with basin may be caused by the high density geologic structures underneath. In addition, combining with other previous results, we consider that the formation of volcanoes may be closely related to the stagnant Pacific slab in the mantle transition zone beneath Northeast China. |
| |
| Keywords: | Joint inversion Gravity data Seismic tomography Density distribution Northeast China |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球物理学报》浏览原始摘要信息 |
| 点击此处可从《地球物理学报》下载免费的PDF全文 |
|
