基于Swarm卫星磁测研究南北构造带及邻域磁异常空间变化

Based on the three-dimensional magnetic survey data measured by the Swarm satellite constellation recently launched by the ESA on November, 2013, and thus derived geomagnetic models, the spatial variations of the lithospheric magnetic anomaly in the North–South tectonic belt and adjacent regions, are investigated, including distribution of the anomaly, differential gradients of east-west, north-south and vertical directions. And also the basic features of the spatial distribution of satellite magnetic anomalies in the North–South tectonic belt and adjacent regions are studied. And on this basis we combined satellite anomalies with historical data from ground and aeromagnetic surveys to construct a three-dimensional model of regional magnetic anomalies. Furthermore, the Curie isothermal surface in the aimed area is estimated from these satellite anomalies above mentioned, and compared with the geophysical fields, such as the depth of the Moho surface, the velocity anomaly of the seismic wave, the electrical structure of the crust, and the gravity anomaly etc.. Which is meant to reveal the relations between the magnetic anomaly distribution, the ups and downs of the basement of magnetic layers and the lithospheric layered structure. And the connection of the magnetic anomaly with the geological structure is studied. The corresponding relationship of the transitional zone of strong and weak anomalies with subareas of tectonic structures and deep fault belts, and the quantitative characteristics of magnetic anomalies and the orogenic zone, the basins are discussed. These discoveries allow us to provide quantitative evidences of magnetic anomaly variations for geologic structure and its evolution, resources exploration and earthquake disasters study, and highlight the importance of understanding geodynamics processes, tectonic movements and geological evolution researches.

根据2013年11月欧空局发射的Swarm磁测卫星星座的立体磁测数据以及以此为基础建立的磁场模型，研究南北构造带及邻域地区岩石圈磁异常的空间变化特点，包括磁异常分布、东西向、南北向和垂直向的磁异常差分梯度。在此基础上，将卫星磁异常与地面、航磁等历史资料相结合，构建区域磁异常三维模型。进而利用上述磁异常估算研究区域的磁基底厚度。通过与莫霍面深度、地震波速度异常、地壳电性结构、重力异常等地球物理场相比较，揭示磁异常分布、磁性层基底起伏与岩石圈结构的联系。研究磁异常空间变化与地质构造之间的关系，探讨磁异常强弱过渡与大地构造分区、深大断裂带的对应关系，磁异常空间变化与造山带、大型盆地的定量特点。这些研究结果可以为该地区地质构造及演化、资源探测、地震灾害研究等提供磁异常空间变化的定量依据，对该区域的地球动力学过程、大地构造运动和地质演化的研究有重要意义。

根据Swarm卫星磁测数据，研究南北构造带及邻域地区岩石圈磁异常东西向、南北向和垂直向的磁异常差分梯度。利用地磁场模型（NGDC-720）和航空磁测数据,研究南北构造带及邻域地区地壳磁异常的空间变化，包括磁异常及其梯度的分布、磁异常随高度的衰减、不同波长成分对总体磁异常的贡献。比较磁异常与重力异常、大地热流、地震活动等地球物理信息的异同特征，探讨地壳磁异常与地质构造的关系。探讨磁异常强弱过渡与大地构造分区、深大断裂带的对应关系，磁异常空间变化与造山带、大型盆地的定量特点。利用磁异常的功率谱技术估算南北构造带及邻区的居里面。将居里面分布与地表热流、地温梯度观测值相结合，探讨地壳热结构特点。研究结果表明：龙门山、三江等造山带的磁异常较弱，盆地（准葛尔盆地、四川盆地等）的异常相对较强。研究区的居里面起伏较大，隆起和凹陷分明，与地表热流值近似成反相关。丽江-剑川-保山-腾冲，剑川-楚雄-昆明-玉溪是两条居里面隆起带，其壳幔热流比较高。沿丽江-小金河断裂、红河断裂附近的居里面隆起带与断裂带走向一致，并与青藏高原物质东流通道部分吻合。云南地区居里面深度的变化范围在20.8–31km之间，平均深度为27.3km。准噶尔盆地及其邻近山脉的莫霍面深度、居里深度和热岩石圈厚度分别为38-52km、32-50km和120-260km，莫霍面深度和居里面大致呈逆对应关系。强烈地震发生的地点、大地热流值高的地区，地壳磁异常为负值或相对较弱。6级以上地震主要发生在在居里面深浅过渡带。这些研究结果可以为该地区地质构造及演化、资源探测、地震灾害研究等提供磁异常空间变化的定量依据，对该区域的地球动力学过程、大地构造运动和地质演化的研究有重要意义。