东北地区重力均衡异常特征的初步研究

本文利用地面实测重力资料和地形高程资料,采用普拉特-海福特(Pratt-ttayford)重力均衡理论模型,取1°×1°方格网,通过使用现成改正表格查取改正值与个别计算点用理论公式计算作校核的方法,计算了我国东北地区75个计算点的均衡重力异常值;并对局部第四系覆盖较厚地区作了第四系密度改正;在此基础上,构制了我国东北N39°—49°,E121°—131°大部分地区的均衡重力异常图;结合区域布格重力异常和区域空间重力异常特征以及莫霍界面的起伏特点作了对比分析和讨论

PRELIMINARY STUDY ON THE STATE OF ISOSTATiC EQUILIBRIUM IN THE NORTHEAST CHINA

In order to provide some fundamental data,we calculated the isostatic anomalies' in most parts of the region (N39°-49°;E121°-131°) by means of Pratt-Hayford isostatic model and using 1°×1° square mesh and the isostatic anomaly map of overall region and the 2°×2°regional isostatic anomaly maps were compilated.The calculations show for this region a configuration of anomaly characteristic of alternate anomalies NNE-trending and an extensive anomalous area in agreement with the relief of Moho.It has been shown that isostatic anomalies are generally in agreement with the high relief and regional Bouguer gravity and free-air gravity anomalies,with areas where isostatic anomalies are not or not well concordant with the Moho relief and the their strike,suggesting an isostatic adjustment for these segments,which is likely to be not interpreted as the Moho relief.These segments are in a state of mass imbalance and deserve to pay more attention and further study for the prediction of earthquakes