摘要
地壳结构是青藏高原深部地球物理探测的主要目标之一.研究了结合功率谱分析的二维经验模态分解(Bidimensional empirical mode decomposition,BEMD)位场分离方法,并将其应用于冈底斯带重磁异常分离中.模型试验结果表明该方法能够分离叠加异常,并可获得场源平均深度的可靠估计值;实际资料处理表明研究区布格重力异常和化磁极异常均可分为由浅到深的3个等效层场源产生的异常组合.其中深部重、磁场以南北分区、东西分块为特征.证明了青藏高原是南北地体的拼接,并且在形成之后持续受到印度板块不均匀地向北推进,使喜马拉雅地体、冈底斯地体的深部物质属性在东西方向上以约88°E和93°~95°E为界存在显著的差异;推断青藏高原南部区域中下地壳的低密度体东西向是不连续的,且在研究区中、东部,南北向低密度体被雅鲁藏布江缝合带切开.
Crustal structure is one of the main targets of deep geophysical exploration in the Qinghai-Tibet Plateau. In this paper,the bi-dimensional empirical mode decomposition (BEMD) separation method combined with power spectrum analysis is studied,and it is applied to the separation of gravity and magnetic anomalies in the Gangdise belt. The model test results show that the method can separate the superimposed anomalies and obtain a reliable estimation of the source depth. The decomposition results in the study area show that the bouguer and the RTP magnetic anomalies can be divided into three anomalies which are induced by three equivalent layer sources from shallow to deep. The deep gravity and magnetic fields are characterized by the north- south partition and the east-west block. It is proved that the Qinghai-Tibet Plateau is formed by splicing the terrains along the north-south direction and after its formation, it is continuously pushed northward by the Indian plate unevenly, which makes the material properties of the Himalayan terrain and the Gangdise terrain have significant differences in deep from east to west bounded by 88°E and 93°-95°E. It is inferred that the low density body is discontinuous in east-west direction and the low density body in the middle and east of the study area is cut by the Yarlung Zangbo suture zone.
作者
胡斌
张贵宾
贾正元
张刚
陈涛
张昌榕
Hu Bin;Zhang Guibin;Jia Zhengyuan;Zhang Gang;Chen Tao;Zhang Changrong(School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2019年第6期1797-1808,共12页
Earth Science
基金
国家重点研发计划(Nos.2016YFC0600301,2017YFC0602204-01,2016YFC0600201)
中央高校基本科研业务费专项资金资助(No.2652016127)
关键词
冈底斯带
重磁异常
二维经验模态分解
功率谱
地壳结构
地球物理
Gangdise belt
gravity and magnetic anomalies
bi-dimensional empirical mode decomposition
power spectrum
crustal structure
geophysics
