Based on an analysis of 1:200000 gravity and magnetic data obtained from northern Hainan

area in combination with geological and drilling data, the authors deduced 20 concealed or semi-

concealed faults and delineated 12 Cenozoic depressions as well as 2 domes and basically found out

characteristics and properties of geological structures in this area. These achievements are of great

significance for further geological-structural studies, city planning and economic construction.