SPATIAL DISTRIBUTION OF MAGNETIC MINERALS ON THE BEACH AND ITS SEASONAL VARIATION: A CASE STUDY OF THE SHILAOREN BEACH IN QINGDAO

This paper surveyed the volume susceptibility and grain size distribution of surface sediments on the Shilaoren Beach in Qingdao formed in different seasons. Combined with the sediment hydrodynamic factors on the beach, it is revealed that the volume susceptibility is higher in the east and lower in the west, and higher in the berm and lower in the beach face. The deposits on the beach are finer in summer but coarser in winter. There is certain relationship between magnetic susceptibility and the characteristics of spatial distribution of sediment particle size on the beach. The susceptibility is related to the grain size, and effected by wave sorting, alongshore current and wind action. In general, high magnetic susceptibility values occur in the erosional area of finer sediments and low value in deposition areas with coarser particles. As a convenient new method of easy operation with low cost, the magnetism method can be used to replace the time-consuming grain size and mineral analysis, to study the beach sedimentary dynamic process and to identify erosional and depositional areas on a beach.