Paleointensity

Absolute paleointensity determinations involve measurements that attempt to quantify the past field strength that produced a magnetization in a rock or other material that has cooled from a high temperature. Most of these methods involve progressively removing the natural remanent magnetization (NRM) by thermal demagnetization and replacing it with a laboratory thermoremanent magnetization given in a magnetic field of known strength and direction.^[2] Various methods for measuring absolute paleointensity include:

• Thellier-Thellier method^[3]
• Shaw method^[4]
• Coe method^[5]
• Athermal paleointensity methods

Relative paleointensity determinations are often used in materials that may be destroyed or strongly altered during heating, such as lake and marine sediments.^[6] A measure of relative changes in paleointensity may be obtained by normalizing the NRM by a factor that represents the concentration of magnetic grains in a sample, such as the anhysteretic remanent magnetization.