近日，中国地震局地球物理研究所吴庆举研究员提出，利用接收函数三维Kirchhoff迁移方法研究华北克拉通中、西部地幔过渡带结构。这一研究成果发表在2024年8月7日出版的国际学术期刊《中国科学：地球科学》上。

研究结果显示，大同火山下方410km的不连续面下沉了约10km，表明在410km深度附近存在高温异常，这可能与MTZ中停滞的太平洋板块脱水引发的小规模地幔上升流有关。热物质的上涌为地表岩浆活动提供了热源。在渤海湾盆地下方660km的不连续面明显下沉，过渡带大面积加厚。研究人员认为该地区的异常与太平洋板块在MTZ中的停滞有关。

虽然南北重力梯度线以西的过渡带厚度正常，但研究人员认为太平洋板块的俯冲没有穿过华北克拉通的重力梯度线。相比之下，在汉诺坝火山北部观测到的660km不连续面的小规模下沉和MTZ的增厚可能表明，板块在其转折点越过重力线性构造并留在MTZ内。此外，在秦岭大别山造山带中观察到局部的MTZ增厚，被认为是岩石圈拆沉进入下扬子区过渡带和太平洋板块停滞的共同作用的结果。

据研究人员介绍，本研究利用ChinArray项目部署的区域性宽带密集临时阵列数据，应用远震P波接收函数的三维Kirchhoff偏移方法，利用东亚地区的高分辨率三维速度模型，研究了华北克拉通(NCC)中西部地幔过渡带(MTZ)的不连续结构。

此外，在秦岭大别造山带观测到MTZ的局部增厚。这被认为是岩石圈向下扬子地区过渡带剥离和太平洋板块停滞的综合作用。

附：英文原文

Title: Structure of the mantle transition zone in the central and western parts of the North China Craton using the receiver function 3D Kirchhoff migration method

Author: Min ZHU, Qingju WU, Jieyuan NING, Ruiqing ZHANG

Issue&Volume: 2024/08/07

Abstract: Using data from the regional broadband dense temporary array deployed by the ChinArray project, we applied the three-dimensional (3D) Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone (MTZ) in the central and western parts of the North China Craton (NCC) using a high-resolution 3D velocity model of the East Asian region. The results show that the 410-km discontinuity beneath the Datong Volcano is depressed by ~10km, indicating the presence of a high-temperature anomaly near the depth of 410km, which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the MTZ. The upwelling of hot material provides a heat source for surface magmatic activity. Beneath the Bohai Bay Basin, significant subsidence of the 660-km discontinuity is observed, and the transition zone here is extensively thickened. It’s suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the MTZ. Although the thickness of the transition zone west of the North-South Gravity Lineament appears normal, we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the NCC. In comparison, the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the MTZ. Furthermore, a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling Mountains. This is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate.

DOI: 10.1007/s11430-024-1339-3

Source: https://www.sciengine.com/SCES/doi/10.1007/s11430-024-1339-3