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自从重力测量工作进入山区以来,对观测结果的各种外部改正已广泛地被人们所重视。这是因为大多数重力异常的解释方法只适用于在平面上测定的△g值。由于地形起伏的影响,而目前对此影响的各种改正方法又均不尽完善,给重力测量成果的地质解释造成了很大的困难。若不追究各种改正模式的准确性,那末,采用目前通用的一般公式进行布伽改正和地形改正时,直接影响精度的原因不外乎高度改正系数∨zz、中间层密度σ及地形改正最大半径R等三个因素。根据全国各地的工作实践表明,在山区,高度改正系数与理论值差别很大,其差别的量级可达几百艾维。众所周知,测区表层岩石的密度值是变化不一的,当在一个地方原为正确的数值,在另一地方就不一定是正确的。同样,由于中间层密度的差异或选择不当,试图单纯地通过扩大改正范围的途径来提高地形改正的精度,又因引入了新的误差而使这一工作毫无益处。上述三种因素的存在,会使布伽异常图产生畸变。也就是说,很容易出现与我们感兴趣的深部物质无关而仅与地形相关的所谓“山形异常”。
Since the gravimetric work into the mountains, various external corrections to the observations have been widely valued. This is because most explanations of gravity anomalies apply only to Δg values measured on a plane. Due to the influence of topography, the various corrections to the current methods have not been perfect, which has caused great difficulties in the geological interpretation of gravity measurement results. Without investigating the accuracy of the various correction modes, the reason for the direct influence on accuracy when using the general equations in general for correction of BuGj and topography is nothing more than the correction coefficient ∨zz, the density σ of the middle layer, and the maximum correction of the terrain Radius R and other three factors. According to the practice of work all over the country, it shows that there is a great difference between the height correction coefficient and the theoretical value in mountainous areas, with the difference up to hundreds of Ivi. It is well known that the density of surface rock in the survey area varies from place to place. When the value is correct in one place, it is not necessarily the right place in another place. Similarly, attempts to increase the accuracy of terrain correction simply by widening the range of corrections due to differences in density or improper selection of the intervening layer would render the effort unprofitable by the introduction of new errors. The presence of the above three factors, will make abnormal aberration Bourgogamy. In other words, so-called “Yamagata anomalies”, which are not related to the deep material of interest but are only related to the terrain, are prone to occur.