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为了探讨渤海基底结构特征,中国科学院海洋研究所调查船“海燕号”用KЦГ—Ⅱ型海底石英重力仪和国产ZH641型金属弹簧海底重力仪在渤海进行了联合观测(范时清,江玉成),完成剖面四条,测点49个,控制面积1700平方公里,全区总测量精度为±1.06毫伽。为了得到单纯由地质不均匀体引起的海底重力变化状况,通过对观测数据的系统校正与运算,求出各测点的海底布格重力异常值,并作出各剖面的布格重力异常曲线。 海底构造的存在,会引起水下各地段密度分布的不均匀或相对的差异性,从而引起海底重力场相应的变化,在一般情况下,局部重力变化与地壳表层地质构造的差异有关,即同岩石成分及其成层条件不同有关,在较致密的岩层接近地表的地方,重力值就增大,反之,重力值就减小。海底重力测量结果表明,渤海中部存在着一个巨大的北北东向的重力低区和各断面布格异常曲线呈大凹陷的地段,反映这里乃是一个沉积盖层较
In order to explore the structural characteristics of the basement of the Bohai Sea, a joint observation (Bo Shi and Jiang Yucheng) was carried out in the Bohai Sea using the KMI-Ⅱ seabed quartz gravity meter and the domestic ZH641 metal-spring seafloor gravimeter by the Institute of Oceanography, Chinese Academy of Sciences. Section 4, measuring 49 points, control area of 1,700 square kilometers, the region’s total measurement accuracy of ± 1.06 milligam. In order to obtain the submarine gravity change caused by the inhomogeneous geology, the seabed gravitational anomaly value of each measuring point was obtained through systematic correction and calculation of the observed data, and the Bouguer gravity anomaly curve of each section was obtained. The existence of the seafloor structure will cause the uneven or relative difference in the density distribution of the submarine segments, which will cause the corresponding changes in the gravity field of the seafloor. In general, the local gravity changes are related to the differences in the geological structure of the crustal surface, Rock composition and stratification of different conditions related to the more dense rock near the surface where the gravity value increases, whereas, the value of gravity decreases. The results of the seabed gravity measurements show that there is a huge north-east-direction low-gravity area in the central Bohai Sea and large depressions in the Bougie anomalous curve of each section, reflecting that this is a sedimentary cover over