牛源源^1,,
郭良辉^1,,,
石磊²,
陈石²,
庄建仓³
1. 中国地质大学(北京)地球物理与信息技术学院, 北京 100083
2. 中国地震局地球物理研究所, 北京 100081
3. 日本国立统计数理研究所, 东京 1908562

基金项目: 中国地震局地球物理研究所基本科研业务费专项资助(DQJB18B03), 国家自然科学基金面上项目(41774098, 41874097, 41774090), 中国-东南亚毗邻区大震活动地球动力学研究(科技部国际合作项目, 2015DFA21206), 中央高校基本科研业务费专项资金和中国地震局震情跟踪面上课题(2018020201)联合资助


详细信息

作者简介: 牛源源, 女, 1994年生, 硕士在读研究生, 主要从事重磁数据处理与反演方法技术研究与应用.E-mail:iamnyy1001@163.com

通讯作者: 郭良辉, 男, 教授, 主要从事地球物理数据精细处理与三维反演方法研究与应用.E-mail:guo_lianghui@163.com

中图分类号: P631

收稿日期:2018-12-26
修回日期:2019-03-25
上线日期:2019-06-05

Estimation of near-surface density based on gravity Bayesian analysis and its application in Yunnan area

NIU YuanYuan^1,,
GUO LiangHui^1,,,
SHI Lei²,
CHEN Shi²,
ZHUANG JianCang³
1. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China
2. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
3. The Institute of Statistical Mathematics, Tokyo 1908562, Japan


More Information

Corresponding author: GUO LiangHui,E-mail:guo_lianghui@163.com

MSC: P631

--> Received Date: 26 December 2018
Revised Date: 25 March 2019
Available Online: 05 June 2019


摘要
摘要:基于布格重力异常相对于地形起伏光滑分布的约束条件，从一维自由空气重力异常数据出发，采用贝叶斯方法估算近地表岩石密度，同时采用三次B样条函数拟合布格重力异常，获取光滑分布的布格重力异常.数据拟合和光滑约束之间的权重采用Akaike贝叶斯准则（ABIC准则）自动确定.均匀剖分模型和不均匀剖分模型数据试验都验证了该方法的有效性.相关参数评价表明，足够多的样条系数可以提高估计结果的准确性，样条系数的个数接近测点数时可获得较稳定的估计结果.增大异常的噪声水平时，ABIC准则可有效地自动增大先验光滑约束的权重.云南地区两条重力剖面应用结果表明，剖面沿线的近地表密度值起伏变化明显（达2.45~2.8 g·cm^-3），前寒武纪和古生代地层密度相对较高（主要为2.53~2.75 g·cm^-3），而中生代密度较低（2.45~2.73 g·cm^-3）；本文估计的近地表密度结果与区域物性资料及地表地质特征较吻合；估计的剖面布格重力异常具有光滑性；红河断裂两侧近地表密度差异较大，可达0.4 g·cm^-3.本文获得的两条剖面近地表密度结构和布格重力异常为该区深部结构与构造研究提供更可靠的重力基础数据.
关键词: 重力异常/
近地表密度/
贝叶斯分析/
ABIC准则

Abstract:Bouguer gravity anomalies are calculated by terrain correction and Bouguer correction to free-air gravity anomaly data. Near-surface density is an important parameter in these two corrections. Assuming that Bouguer gravity anomalies vary smoothly with surficial topography, we estimate the near-surface density from 1-D free-air gravity anomalies by using the Bayesian method and simultaneously obtain the smooth Bouguer anomalies fitted by the cubic B-spline function. We determine the trade-off parameters between the data misfit and prior constraints automatically by the Akaike's Bayesian Information Criterion (ABIC). Synthetic data tests by using uniform and non-uniform subdivisions verify the effectiveness of the presented method. Relevant parameter evaluations show that more of the spline coefficients are involved in the method, better results will be produced. When the number of spline coefficients are close to the number of observed stations, a more stable estimation can be obtained. More noise in the data, higher weight for smooth constraints will be determined automatically by the ABIC algorithm. The application of this method to two gravity profiles in the Yunnan area shows that near-surface density along the profiles varies significantly (2.45~2.80 g·cm^-3). The Proterozoic and Paleozoic strata have relatively high density (mainly 2.53~2.75 g·cm^-3), and the Mesozoic strata have relatively low density (2.45~2.73 g·cm^-3). The estimated near-surface density in this paper is in a good agreement with regional physical data and surface geological characteristics, and the estimated Bouguer gravity anomalies have good smoothness. The density differences between both sides of the Honghe fault are as large as 0.4 g·cm^-3. The near-surface density structure and Bouguer gravity anomalies obtained in this paper provide reliable basic data for the study of deep structure in this area.
Key words:Gravity anomaly/
Near-surface density/
Bayesian analysis/
ABIC



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