王振宇^1,,
佘雅文^2,3,
付广裕^1,,,
皮誉洋⁴
1. 中国地震局地震预测重点实验室(中国地震局地震预测研究所), 北京 100036
2. 河北省地震局, 石家庄 050021
3. 中国地震局地球物理研究所, 北京 100081
4. 中国地震局地震研究所, 武汉 430071

基金项目: 国家自然科学基金（41574071），国家国际科技合作专项（2105DFR21100），地震预测研究所基本科研业务费专项（2016IES010204）与河北省地震局地震科技星火计划项目（DZ20170510054）联合资助


详细信息

作者简介: 王振宇, 男, 硕士研究生, 主要从事重力观测与解释研究.E-mail:15116181259@163.com

通讯作者: 付广裕, 男, 博士, 研究员, 主要从事地震位错与重力均衡研究.E-mail:fugy@cea-ies.ac.cn

中图分类号: P542

收稿日期:2017-04-09
修回日期:2017-09-30
上线日期:2018-06-05

Density structures of crust and vertical tectonic stress field of lithosphere in Northeast Asia

WANG ZhenYu^1,,
SHE YaWen^2,3,
FU GuangYu^1,,,
PI YuYang⁴
1. Key Laboratory of Earthquake Prediction, Institute of Earthquake Forecasting, Chinese Earthquake Administration, Beijing 100036, China
2. Hebei Earthquake Agency, Shijiazhuang 050021, China
3. Institute of Geophysics, Chinese Earthquake Administration, Beijing 100081, China
4. Institute of Seismology, Chinese Earthquake Administration, Wuhan 430071, China


More Information

Corresponding author: FU GuangYu,E-mail:fugy@cea-ies.ac.cn

MSC: P542

--> Received Date: 09 April 2017
Revised Date: 30 September 2017
Available Online: 05 June 2018


摘要
摘要:本文利用EIGEN-6C4重力数据和ETOPO1地形数据，在考虑物质密度横向不均匀的情况下，在东北亚地区展开地壳均衡研究，并重点分析了长白山的隆升机制.首先，针对穿越长白山和库页岛的两条近乎东西向的剖面（剖面A、B）展开详细研究，以CRUST1.0模型为初始条件，利用布格重力异常数据，基于Airy模型和Airy-Pratt模型分别反演了相应剖面的地壳密度结构，发现两剖面的地壳密度呈现一定程度的横向不均匀特性；接着基于上述密度结构和高程数据，利用Airy均衡理论计算了相应剖面的均衡面深度，并进一步比较莫霍面（Moho）和均衡面的差异，计算了剖面的垂向构造应力分布；然后，把上述方法应用到整个东北亚地区，计算了1°采样的21条东西向剖面的垂向构造应力，插值得到整个东北亚地区的垂向构造应力分布.结果表明，东北亚大部分地区垂向构造应力基本为零，总体处于均衡状态，长白山地区垂向构造应力为-15~-25 MPa，日本列岛垂向构造应力为-40~-50 MPa，太平洋海沟垂向构造应力为15~25 MPa；最后，本文运用自由空气重力异常导纳方法，计算了长白山地区的有效弹性厚度（T_e）和加载比，发现长白山地区的T_e为10 km，表明该地区的岩石圈较为柔软；加载比结果显示，岩石圈初始加载主要来自莫霍面，占总加载的78%，表明长白山的隆升主要源自地幔物质上涌.
关键词: 布格重力异常/
Airy均衡理论/
地壳密度结构/
垂向构造应力/
自由空气重力异常导纳方法

Abstract:Considering the lateral density variation of crust, we investigate the isostatic state of Northeast Asia with the utilization of EIGEN-6C4 gravity data and ETOPO1 topography data, and analyze the uplifting mechanism of the Changbai Mountain. First, we study in detail two profiles in roughly east-west direction which stretch over Changbai Mountain and Sakhalin Island (profile A & B). Specifically, taking CRUST1.0 model as initial conditions, we inverse the density structure of Crust along the two profiles with Bouguer gravity anomalies, using Airy and Airy-Pratt isostasy theories, respectively. The results show that, to some degree, there is lateral inhomogeneity in the crust density structure along the profiles. Then, according to the inversed density structures and topography data we calculate the depth of isostasy along each profile. Based on the comparison of the depth of isostasy with the one of Moho, we calculate the vertical tectonic stress of the two profiles. And then, with the method illustrated above, we calculate the vertical tectonic stress along 21 profiles in exactly east-west direction within our study area, with sampling interval of 1 degree. By interpolating the above results we obtain the distribution of the vertical tectonic stress of the whole Northeast Asia. In total, the crust of Northeast Asia, whose vertical tectonic stress is about 0, is in isostatic state. Among which, the vertical tectonic stress at the Changbai Mountain is -(15~25) MPa, at Japan Islands is -(40~50)MPa, and at the Pacific trench is 15~25 MPa. Finally, we estimate the effective elastic thickness (T_e) and the load ratio of the area around the Changbai Mountain, using the method of Free-air gravity anomaly admittance. The result shows that the T_e of the Changbai Mountain is about 10 km, which mean that the lithosphere of the area is relatively soft. The initial load is mainly from the Moho, about 78% of total load, which suggest that the uplifting of the Changbai Mountain was mainly resulted from the uplifting of material of the Mantle.
Key words:Bouguer gravity anomaly/
Airy isostasy theory/
Crust density structure/
Vertical tectonic stress/
Free-air gravity anomaly admittance method



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