Analysis of magnetic properties rocks and soils around the Danau Diatas, West Sumatra

The magnetic characteristics of the rocks have different magnetic properties of each kind. If this rock experiences weathering, then the rock material will be carried around the area such as the lake, through the wind, the water is then sedimentated. These sediments can also come from dust from volcanic eruptions (volcanic ash) where the magnetic properties that come from surrounding rocks are different from the magnetic properties derived from dust from volcanic eruptions. This study was used to determine the magnetic characteristics of rocks and soil around the Danau Diatas West Sumatra, which is one source of sediment. This the magnetic properties can be determined using rocks magnetism method that are commonly used to determine the magnetic properties of a material nature. Characteristics magnetic determined through test susceptibility magnetic using Bartington MS2B (Magnetic Suceptibility sensor B) dual frequency of 470 Hz and 4.7 kHz. Results this study shows values χ LF (susceptibility low frequency), χhf (susceptibility high frequency) and χfd % (susceptibility frequency dependent ). Value of susceptibility of rocks and soil obtained variations in the range of 23.77 × 10−8 m3 / kg - 2791.6 × 10−8 m3 / kg and 17.4 × 10−8 m3 / kg - 2804.4 × 10−8 m3 / kg. The value of magnetic suceptibility of rock and soil is included in the ferromagnetic mineral group and the types of minerals contained there in are ilmenite (FeTiO3) and hematite (Fe2O3). The value of frequency-dependent magnetic susceptibility χfd (%) ranges from 0.4% to 13.5%. For the value of χfd (%) 0.4% - 1.1% means that there is no or contains less than 10% superparamagnetic grain, for the value of χ fd (%) 3.3% means the mixture of superparamagnetic grain and coarser non-superparamagnetic grain, or superparamagnetic grain measuring < 0.005μm, and for the value of χ fd (%) 13.5%, meaning that the whole or consists of more than 75% superparamagnetic grains.