[1] Jilin Univ, Coll Geoexplorat Sci & Technol, Changchun 130026, Jilin, Peoples R China
[2] Minist Land & Resources, Key Lab Appl Geophys, Changchun 130026, Jilin, Peoples R China
[3] Uppsala Univ, Dept Earth Sci, Villavagen 16, S-75236 Uppsala, Sweden