中国及邻区岩石层大地水准面正演模拟
|
摘要
依据地震层析成像、地震测深和大地电磁测深结果给出的地球内部结构和物性分布 ,模拟了中国及邻区岩石圈中短波长大地水准面起伏。正演模拟结果显示 :地形起伏引起的大地水准面异常巨大 ,幅值变化可达 2 10 m,最大值在青藏高原 ,达 150余 m。沉积层底面起伏产生的大地水准面异常非常小 ,幅值只有 6.5m,表现出短波长特征。岩石层底面起伏产生的大地水准面异常极为平缓 ,约为 2 0 m。莫霍面产生的大地水准面异常形态与地形起伏引起的大地水准面异常形态相近 ,异常幅值只有后者的 2 / 3,在青藏高原只有后者的一半。岩石层内密度不均匀引起的大地水准面异常的幅值约为 75m。
In this paper the geoid anomalies of middle short wavelength of China and its adjacent region are simulated on the basis of internal earth structure and distribution of density,which results from data of tomography,seismic sounding and telluric electromagnetic sounding.The simulation results show that the geoid anomaly casused by topography is much huge that its amplitude reaches 210 meters and the highest geoid anomaly,which is on the Tibet plateau, reaches over 150 meters.In the same time the geoid anomaly caused by sediment layer is very low,only 6.5 meters and shows short wave character. The Lithospheric geoid anomaly is about 20 meters. The form of the geoid anomaly caused by the Moho interface is similar to that of the topographic geoid anomaly,but the amplitude is less than the later by a factor of 1/3.The geoid anomaly caused by the uneveness of the lithospheric density is about 75 m.
In this paper the geoid anomalies of middle short wavelength of China and its adjacent region are simulated on the basis of internal earth structure and distribution of density,which results from data of tomography,seismic sounding and telluric electromagnetic sounding.The simulation results show that the geoid anomaly casused by topography is much huge that its amplitude reaches 210 meters and the highest geoid anomaly,which is on the Tibet plateau, reaches over 150 meters.In the same time the geoid anomaly caused by sediment layer is very low,only 6.5 meters and shows short wave character. The Lithospheric geoid anomaly is about 20 meters. The form of the geoid anomaly caused by the Moho interface is similar to that of the topographic geoid anomaly,but the amplitude is less than the later by a factor of 1/3.The geoid anomaly caused by the uneveness of the lithospheric density is about 75 m.
引文
1 Dziewonski A M,Hager B H,O'Connell R J.L arge scale heterogeneities in lower mantle.J.Geophys.Res.,1977,82 ,2 39～ 2 55.
2 Richards M A,Hager B H.Geoid anomaly in a dynamic earth.J.Geophys.Res.,1984 ,89,60 0 3～ 60 15.
3 Hager B H.Subducted slabs and the geoid:Constrains on mantle rheology and flow.J.G.res.,1984 ,89(B7) ,60 0 3～ 60 15.
4 Hager B H,Richards M A.Long- wavelength in earth's geoid:physical models and dynamical implications.Phil Trans.R.soc.L ond.A32 8,1989,30 9～ 32 7.
5 Kogan M G,Mc Nutt M K.Gravity field over northen of the upper mantle.Science,1993,2 59,4 73～ 379.
6 许厚泽 ,陆仲连 .中国地球重力场与大地水准面 .北京 :解放军出版社 ,1997.
7 Dziewonski A M.Mapping the lower mantle:determination of lateral heterogeneity in P velocity up to de-gree and order6.J.Geophys.Res.,1984 ,89( B7) ,5959～ 5952 .
8 Cadek O,Martinec Z.Spherical Harmonic expansion of the earth's crustal thickness up to degree and order30 .Studia geoph.,1991,35,151～ 165.
9 朱介寿 ,曹家敏 ,李显贵 ,等 .中国及邻区地球三维结构初始模型的建立 .地球物理学报 ,1997,4 0 ( 5) :62 7～648.
10 Biwin C.Depth of principal mass anomalies contributing to earth's undulations and gravity anomalies.Marine Geodesy,1983,7:61～ 10 1.
11 陆洋 ,许厚泽 .72 0阶高分辨率重力场模型 IGG97L研究 .地壳形变与地震 ,1998,18( Supp.) ,1～ 7
2 Richards M A,Hager B H.Geoid anomaly in a dynamic earth.J.Geophys.Res.,1984 ,89,60 0 3～ 60 15.
3 Hager B H.Subducted slabs and the geoid:Constrains on mantle rheology and flow.J.G.res.,1984 ,89(B7) ,60 0 3～ 60 15.
4 Hager B H,Richards M A.Long- wavelength in earth's geoid:physical models and dynamical implications.Phil Trans.R.soc.L ond.A32 8,1989,30 9～ 32 7.
5 Kogan M G,Mc Nutt M K.Gravity field over northen of the upper mantle.Science,1993,2 59,4 73～ 379.
6 许厚泽 ,陆仲连 .中国地球重力场与大地水准面 .北京 :解放军出版社 ,1997.
7 Dziewonski A M.Mapping the lower mantle:determination of lateral heterogeneity in P velocity up to de-gree and order6.J.Geophys.Res.,1984 ,89( B7) ,5959～ 5952 .
8 Cadek O,Martinec Z.Spherical Harmonic expansion of the earth's crustal thickness up to degree and order30 .Studia geoph.,1991,35,151～ 165.
9 朱介寿 ,曹家敏 ,李显贵 ,等 .中国及邻区地球三维结构初始模型的建立 .地球物理学报 ,1997,4 0 ( 5) :62 7～648.
10 Biwin C.Depth of principal mass anomalies contributing to earth's undulations and gravity anomalies.Marine Geodesy,1983,7:61～ 10 1.
11 陆洋 ,许厚泽 .72 0阶高分辨率重力场模型 IGG97L研究 .地壳形变与地震 ,1998,18( Supp.) ,1～ 7
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心