Abstract:Borehole magnetometry is mainly used to measure the magnetic field of the space magnets around boreholes. It can play a role in prospecting or solving some geological problems. In general survey of iron deposit, it is found that the borehole generally passes through or close to the ore body, and magnetic difference between the ore body and the surrounding rock is large, thus, it is easier to discover the blind ore near the hole by magnetic logging. The iron deposit of Jiuxian area in Dongping county of Shangdong province belongs to sedimentary metamorphic iron deposit. The surrounding rocks have no or very weak magnetic, and have physical basis of magnetic prospecting.The main ore body of this deposit is buried deeply with thin ore bodies, therefore it is difficult to explore. The discovery of the ore body is benefit from the secondary exploitation of geological and geophysical data. Threecomponent borehold magnetometry plays an important role in deep exploration. Through threecomponent magnetic logging in ZK408 borehole, the existence of blind ore in bottom hole is accurately predicated, which provides a reliable basis for the determination of drilling continuity, reducing drilling workload and saving production cost without guaranteeing the leakage of magnets, reasonably inferring the occurrence state and spatial location of magnets in exploration area, and evaluating the iron ore reserves in Jiuxian iron deposit of Dongping county. The evaluation provides geophysical basis for further geological work. The threecomponent magnetic logging in borehole has a scientific and accurate guiding role in searching for deep magnetic ore bodies. Its technical method provides a new idea for deep and peripheral prospecting in Jiuxian iron deposit.
