Thermoremanent magnetization

Thermoremanent magnetization is a stable magnetization acquired when magnetic minerals cool through their Curie or blocking temperatures in an ambient magnetic field.

Curie temperature: The temperature above which a ferromagnetic or ferrimagnetic material loses spontaneous magnetic order. Above this threshold, thermal agitation erases the ordered magnetization that cooling can later lock in.
Paleomagnetism: The study of Earth's ancient magnetic field recorded in rocks, sediments, and archaeological materials. Thermoremanent magnetization is a principal record used to reconstruct ancient field directions.
Chemical remanent magnetization: A stable magnetization acquired as magnetic minerals form or alter in a chemical environment. It develops through mineral growth or alteration rather than cooling through magnetic transition temperatures.
Lava flow: A mass of molten rock that erupts and moves across Earth's surface before solidifying. Cooling lava commonly acquires a strong record of the ambient field.
Blocking temperature: The temperature below which a magnetic particle's moment remains stable over a specified observation time. Small grains can lock in magnetization below the Curie temperature as their moments become stable.
Archaeomagnetism: The study of past geomagnetic field changes using magnetization in archaeological materials. Fired structures can preserve thermoremanent magnetization useful for dating and field reconstruction.
Depositional remanent magnetization: A magnetization acquired as magnetic grains align with Earth's field while settling and becoming fixed in sediment. It records grain alignment during deposition rather than cooling of magnetic minerals.
Kiln: A thermally insulated chamber used to fire or heat materials at controlled temperatures. Fired kiln walls and contents can acquire remanence aligned with the field during cooling.
Magnetic domain: A region in a magnetic material where atomic magnetic moments share a common direction. Domain configurations determine how remanence develops as mineral grains cool.
Geomagnetic reversal: A transition in which Earth's magnetic field reverses its polarity. Cooling lavas preserve polarity changes as thermoremanent magnetization.

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