{"thcode":2,"term":{"code":860,"name":"paleomagnetic analysis","parent":619,"scope":"Determination of the intensity and direction of residual magnetism in rocks to study changes in the earth's magnetic field during past geologic time."},"uf":[],"bt":[{"code":619,"name":"laboratory methods","parent":734,"scope":"Techniques to analyze and test samples in a place equipped and designed for the work."},{"code":734,"name":"methods","parent":1,"scope":"Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[{"code":225,"name":"Curie temperature analysis","parent":860,"scope":"Analysis of rock specimens using the Curie temperature point above which ferromagnetic materials lose permanent magnetism."},{"code":620,"name":"laboratory-induced magnetization analysis","parent":860,"scope":"Laboratory method to study rocks using magnetometers to measure remanent magnetic fields induced in the samples."},{"code":678,"name":"magnetic hysteresis analysis","parent":860,"scope":"Nondestructive evaluation of ferromagnetic materials.  The evaluation is based on measurement of the variation of intensity of magnetization within an applied magnetic field due to changes in the magnetic domain structure of the materials under study."},{"code":680,"name":"magnetic susceptibility analysis","parent":860,"scope":"Nondestructive evaluation and location of magnetic materials in rock based on measuring the intensity of attraction of the materials to an induced magnetic field. Applications include geological and soil surveys, paleomagnetic studies, sedimentology, archaeological prospecting and core logging."},{"code":771,"name":"natural remanent magnetization analysis","parent":860,"scope":"Method which measures the intensity and direction of residual magnetism in rocks to determine their age and history."}],"rt":[{"code":470,"name":"geophysics","parent":291,"scope":"Branch of geology studying the physical characteristics and phenomena of the earth and its atmosphere."}]}