Indonesia Conference Directory

The identification of rock magnetic properties by magnetic susceptibility has been done on rock weathering of rip rap in Lahor Dam, Malang regency. The aim of this study was to determine the magnetic properties of weathered and unweathered rocks of basaltic and basaltic andesite by measuring magnetic susceptibility and analysis of magnetic domain distribution. Samples were tested using Bartington Magnetic Susceptibility Meter (MS2B) to determine the value of magnetic susceptibility. The result of susceptibility test shows that low frequency susceptibility (χlf) of the outer part of potentially weathered rock has values ranged from (314-1,068) x 10-8m3kg-1 for basalt with average 601.63 x 10-8m3kg-1 , and the inner part (296-790) x 10-8m3kg-1 , with average 546.28 x 10-8m3kg-1. The average of dependent frequency susceptibility (χfd) for this rock is about 0.703%. Meanwhile for the outer part of basaltic andesite has low frequency susceptibility (χlf) ranged from (343-2,744) x 10-8m3kg-1, with average 1,175.57 x 10-8m3kg-1 , and the inner part ranged from (341-2,681) x 10-6m3kg-1 , with average 808.96 x 10-8m3kg-1. The average of dependent frequency susceptibility (χfd) for this rock is about 0.715%. So it can be concluded that the magnetic susceptibility of the outer part of rock is higher than that of the inner part. There is no differences of magnetic domain distribution between inner and outer part of rock during weathering process and all the samples have a tendency to multidomain magnetic grains (MD).