用压缩质面法估算海区地壳厚度的几点认识

用于反演重力资料以估算地壳构造的压缩质面法最早由刘元龙和王谦身提出。后来,沈剑平与王和明又进一步提出了用于反演不等点距重力资料经预调整的压缩质面法。笔者根据海区的特殊情况,运用此法进行了多项试验性计算。具体作法是:<1>将布格重力异常平滑滤波后不等点距采样并考虑沉积层的影响;<2>等点距取平滑滤波后的布格重力值进行计算;<3>等点距取自由空气重力异常值,用二维方柱体公式正演作水层布格改正,

CALCULATING THE CRUSTAL THICKNESS IN THE SEA AREA WITH THE METHOD OF COMPRESSED-MASS PLANE

Experimental calculations of gravity profile in SE 120 direction through the East China Sea shelf, Okinawa trough, Ryukyu arc, Ryukyu trench to oceanic basin have been made by author with the method of compressed mass plane for recalculating the crustal thickness. Based on the analyses of calculation, some opinions to calculate crustal thickness from gravity data are presented as follows. 1. Eliminating the effect of water layer and sediments prior to smoothing filter wave and recalculating. 2. Sampling distance better be equal or greater than the depth of known point. 3. Determination of accepting or rejecting sediments depends on relative variation with the known point. 4. Number of extension at both ends of each line ranging from five to seven. 5. Number of smooth filter wave depends on regional tectonics and point distance in general, five is advisable.