Wybrane zagadnienia badań magnetycznych i grawimetrycznych na przykładzie poszukiwań złóż surowców stałych w Sudetach i NE Polsce

Abstract

SELECTED PROBLEMS OF MAGNETIC AND GRAVIMETRIC SURVEYS EXEMPLIFIED BY EXPLORATION FOR SOLID MINERALS RESOURCES IN THE SUDETES MOUNTAINS AND NE POLANDSummaryResults at detailed geophysical work in the Sudetes mountains and NE Poland are reported and discussed as examples of the effectiveness of the magnetic and gravimetric surveys carried out far solid minerals purposes.Detailed magnetic and gravimetric surveys confined to minor serpentinite areas in the Sudetes mountains revealed local gravity anomalies and differentiation of the magnetic field intensity. Local gravity anomalies may be due to chromite lenses, while zones of lower Δ Z values may reflect veins or tectonic zones to which chromite deposits are frequently related (Fig. 3). The planned boreholes are expected to provide information whether or not local gravity anomalies and zones of lower Δ Z values are related to chromite deposits.Detailed magnetic survey completed in the Krzemianka area (NE Poland) enabled to distinguish several anomalous areas connected with strongly magnetized rocks in the crystalline basement occurring at the depth lower than 800 m (Fig. 4). Examinations of the physical parameters at drilling samples indicate that in the area discussed the highest magnetization is shown by ilmenite-magnetite ores occurring in norite-anorthositic rocks. On the basis of a semi-detailed magnetic and gravimetric survey anomalous areas related to strongly magnetized rocks have been traced out also in the whole Suwałki anorthosite massif (Fig. 5).The magnetic surveys provided valuable information that contributed to the discovery of ilmenite-magnetite ores in NE Poland and facilitated an effective location of development boreholes.