摘要
针对一般大地电磁(MT)反演垂向分辨率低、存在体积效应等问题,本文采用一种基于交叉梯度速度结构约束的三维宽频大地电磁反演方法。该方法通过引入地震速度模型的结构信息,利用交叉梯度函数实现了速度模型对大地电磁反演的结构约束,降低了反演多解性并提升深部构造刻画精度。本研究反演均采用有限内存拟牛顿法(LBFGS),并通过简单理论模型以及大尺度复杂模型验证方法的有效性。本文对北祁连—河西走廊地区的宽频大地电磁实测数据进行反演应用,并用相对应的宽角反射地震测深剖面结果进行约束反演。结果表明,该约束方案应用于实测的宽频大地电磁反演能显著改善异常体的边界清晰度以及深部异常体的响应,其中测区地壳高阻体H1、H2与寒武纪基底相关,其几何形态对应了南北挤压环境下发育的逆冲断裂;低阻体L1反映下地壳—上地幔高导层,成因与北祁连洋俯冲残留、软流圈上涌及其部分熔融有关,宽滩山断裂(KTF)与黑山-金塔断裂(HS-JTF)为深部热液向浅部运移提供了通道。
To address the challenges of low vertical resolution and volumetric effects in magnetotelluric(MT)inversion,this studyproposes a three-dimensional broadband magnetotelluric inversion method incorporating cross-gradient velocity structure constraints.By integrating structural information from seismic velocity models through a cross-gradient function,this approach establishesstructural constraints of velocity models on MT inversion to mitigate solution non-uniqueness and enhance imaging precision of deep-seated structures.The limited-memory Broyden-Fletcher-Goldfarb-Shanno(LBFGS)optimization algorithm was systematicallyimplemented for inversion processes,with validation conducted through both simple theoretical models and large-scale complexsynthetic cases.Practical application was performed on broadband MT field data from the North Qilian-Hexi Corridor region,incorporating constraints from coincident wide-angle reflection seismic sounding profiles.Results demonstrate that the constrainedinversion scheme effectively enhances boundary definition of anomalies and improves deep structural responses in field dataapplications.These findings provide critical evidence for crustal evolution processes and metallogenic environments in the studyarea.
作者
郑礼洋
王堃鹏
郭长安
杨剑
余长恒
陈楚桐
张凌霄
安红颖
吴豪
唐煜杰
ZHENG Liyang;WANG Kunpeng;GUO Chang'an;YANG Jian;YU Changheng;CHEN Chutong;ZHANG Lingxiao;An Hongying;WU Hao;TANG Yujie(Key Laboratory of Earth Exploration and Information Techniques of Ministry of Education,Chengdu University of Technology,Chengdu 610059,China;Geophysical Survey Center of China Geological Survey,Langfang 065000,China;ChengduCenter,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610218,China;ShandongUniversity of Science and Technology,Qingdao 266590,China;Sichuan Resources Group Geophysical Prospecting Institute,Chengdu 610051,China)
出处
《沉积与特提斯地质》
北大核心
2025年第4期884-896,共13页
Sedimentary Geology and Tethyan Geology
基金
“地面分布式大地电磁数据智能处理与地空电磁联合反演解释软件研发”项目(2023YFB3905004)
广西重点研发项目(桂科AB23026062)
四川省科技计划(2024ZHCG0112)
中国地质调查局“北山及邻区区域地球物理调查”项目(DD20230254)。
