Inversion of gravity and topography data for the crust thickness of China and its adjacent region∗
HUANG Jian-ping (黄建平) FU Rong-shan (傅容珊) XU Ping (许 萍)
HUANG Jian-hua (黄建华) ZHENG Yong (郑 勇)
School of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China
Abstract
The data of Bouguer gravity and topography are inverted to obtain the 英语论文范文crust thickness of China. In order to reducethe effect of regional non-isostasy we corrected the reference Moho depth in the inversion with regional topographyrelief, and performed multiple iterations to make the result more reliable. The obtained crust thickness ofChina is plotted on a map in cells of 1°×1°. Then we analyzed the correlation between the Bouguer gravity anomalyand fluctuation of the Moho depth. A good linear correlation is found, with a correlation coefficient of −0.993.
Different correlation coefficients, 0.96 and 0.91, are found for the data in land and ocean region, respectively. Thecorrelation result also shows that the boundary between land and ocean is generally along the bathymetric line of−800 m. In order to examine the influence of the Earth′s curvature on the calculated result, we tried two inversion
models: the inversion for the whole region and the inversion for 4 sub-regions. The difference in the crust thickness
deduced from the two models is less than 5 km. Possible explanation for the difference is discussed. After
comparing our result with that of other studies, we suggest that with our method the Bouguer gravity and the topography
data can be independently inverted to obtain the crust thickness of China and its adjacency.
Key words: Bouguer gravity anomaly; crust thickness; gravitational isostasy
CLC number: P313.2 Document code: A
Introduction
Since the middle of the century, gravitational isostasy has been a fundamental hypothesis forinverting the gravity data to find the crust thickness. Geophysicists have done a lot of researches
on using gravity data to investigate the depth of Moho discontinuity. Since 1980, the InternationalLithosphere Program emphasized the importance of investigating the Moho depth variation.
Thereafter a lot of results have been published in the world (Braitenberg et al, 2000; Kaban et al,
1999; Banjeree and Satyaprakash, 2003; Chuej, 1979; King et al, 2002). Many Chinese geophysicistsalso did important works. ZENG et al (1995) compiled a map of crust thickness of China
based on the DSS data. LIU et al (1987) proposed a method of utilizing gravity data to calculate
the crust thickness. Some studies gave the crustal velocity structure for different areas of China
(YAO et al, 1994; FANG, 1999). FU (1984, 1988) developed a method to calculate the crust
thickness. ZHANG et al (2004) deduced the crust thickness of the southern Qinghai-Xizang Plateau
based on seismic body wave data. Using the gravity and geomagnetic data JIANG et al (2003)
∗ Received 2005-07-11; accepted in revised form 2006-03-11.
Foundation item: KZCX3-SW-131
Author for correspondence: [email protected]
No.3 HUANG Jian-ping: INVERSION OF GRAVITY AND TOPOGRAPHY DATA 265
obtained the crust thickness for the Okinawa Trough and its adjacent region. At the same time
WANG et al (2001) derived the crust velocity structure of the Tianshan mountain region based on
the data of seismic reflection profile. However, due to the limitation of station coverage, from the
modern seismic data one can usually obtain only a 2D crust structure, and then extrapolate it to the
3D space. It is usually difficult to obtain a 3D crust structure directly. On the contrary, the gravity
data can always be used to deduce the 3D variation of crust thickness.
In the traditional approach of deducing crust thickness from gravity data one often chooses a
uniform crust depth as the reference for the whole studied region. However, in the region with
large variation of topography use of a single reference depth would introduce significant systematic
errors in the calculated cru
