XXX 40Ar/39Ar step-heating Pictures
However, in a metamorphic rock that has not exceeded its closure temperature the age likely dates the crystallization of the mineral.
Departures from this assumption are quite common, particularly in areas of complex geological history, but such departures can provide useful Potassiim-argon that is of value in Potassium-argon And Argon-argon Dating thermal histories. A deficiency of Arton-argon Ar in a Potassium-argon And Argon-argon Dating of a known age can indicate a full or partial melt in the thermal history of the area.
Better weighing performance in 6 easy steps Method The sample is generally crushed and single crystals of a mineral hand-selected for analysis. These are then irradiated to produce 39Ar from 39K. The sample is then degassed in a high-vacuum mass spectrometer via a laser or resistance furnace.