中国大陆及其邻区岩石层挠曲强度变化和均衡补偿机制

THE VARIATIONS OF LITHOSPHERIC FLEXURAL STRENGTH AND ISOSTATIC COMPENSATION MECHANISMS BENEATH THE CONTINENT OF CHINA AND VICINITY

利用中国大陆以及最近与俄罗斯拼接的中亚地区的布格重力和地形数据，采用响应函数和互相关函数技术，结合弹性板挠曲理论，研究了中国大陆及其邻近地区（２５°Ｎ－７０°Ｎ，５０°Ｅ－１４０°Ｅ）的岩石层强度，用现代均衡的观点探讨了研究区的均衡补偿机制．研究结果表明，整个中国大陆及其邻近地区的有效弹性厚度Ｔｅ值为３５ｋｍ．其中，青藏地区Ｔｅ值为８５ｋｍ．西伯利亚西部至乌拉尔Ｔｅ值为７５ｋｍ，天山、塔里木盆地Ｔｅ值为４０ｋｍ，帕米尔高原Ｔｅ值为２５ｋｍ左右，西伯利亚中部、蒙古以及中国东北北部Ｔｅ值为４０ｋｍ，华北Ｔｅ值为２５ｋｍ，华南Ｔｅ值为４０ｋｍ．均衡补偿对于波长大于几千米的地形负荷为局部补偿，对几百公里到１１００ｋｍ的地形负荷为局部补偿和岩石层强度所支持，短波长地形负荷基本上由岩石层强度所支持．

Using Bouguer gravity anomalies and topography data over the continent of China and newly merged Bouguer gravity in the vicinity of China from China and Russia, the elastic strength of lithosphere beneath China and vicinity have been estimated by admittance and coherence technique. The observed admittance and coherence show the effective elastic thickness is about 30-40 km in China and vicinity, about 80-90 km in Tibetan Plateau, about 70-80 km in central Siberia to Ural, about 40-50 km in Tienshan and Tarim, about 25 km in Parim, about 20-30 km in China-Korea platform, about 40 km in southern China. The results obtained from surface and subsurface load model indicate the load with wavelength greater than 1100 km are locally compensated, loads with wavelengths in the range 110-1100km are partially supported by the strength of the lithosphere, and loads with wavelength less then 110km are almost completely supported by lithosphere strength.