Identification of magnetic minerals in the peatlands cores from Lake Diatas West Sumatra, Indonesia

Abstract

Peatlands in Lake Diatas can store various types of minerals. One of the mineral phases that can be found in peatlands are magnetic minerals derived from volcanic eruptions. This study was used to determine concentration of magnetic minerals found in peatlands. We applied the rock magnetism method, measuring the magnetic susceptibility of peat sediments to estimate the concentration of magnetic minerals within a peat core. Bartington Magnetic Susceptibility Meter type MS2C and dual frequency MS2B types, namely 470 Hz and 4.7 k Hz. In this study we analysed the magnetic susceptibility of core Diatas REP B at depths of 0-170 m and 240-720 m. From MS2B the values of low frequency magnetic susceptibility (χif )and high frequency magnetic susceptibility (χhf ) are obtained. The magnetic susceptibility values ranged from 365,2 × 10−8 m3/kg to 386,8 × 10−8 m3/kg and the value of magnetic susceptibility depends on frequency (%χfds ) range between 0,6 % - 1,3%. These low values indicate that almost no superparamagnetic grains are present. We identified a positive peak in magnetic susceptibility 386,8 × 10−8 m3/kg at 693 cm, whereas the lowest values were messured 365,2 × 10−8 m3/kg at 675 cm. Based on the value of magnetic susceptibility, the dominant magnetic mineral phases are Hematite (Fe2O3) and ilmenite (FeTiO3).