Thermochronology

A typical thermochronological study will involve the dates of a number of rock samples from different areas in a region, often from a vertical transect along a steep canyon, cliff face, or slope.

With some knowledge of the subsurface thermal structure, these dates are translated into depths and times at which that particular sample was at the mineral's closure temperature.

[1] Common isotopic systems used for thermochronology include fission track dating in zircon, apatite, titanite, natural glasses, and other uranium-rich mineral grains.

In a closed system, the amount of radiogenic isotopes present in a sample is a direct function of time and the decay rate of the mineral.

[3] At high temperatures, the rocks will behave as if they are in an open system, which relates to the increased rate of diffusion of the daughter isotopes out of the mineral.

[4] This temperature is dependent on several assumptions, including: grain size and shape, a constant cooling rate, and chemical composition.

These are due to a fast charged particle, released from the decay of Uranium, creating a thin trail of damage along its trajectory through the solid.

[11] By determining the relative date and temperature of a sample being studied, geologists are able to understand the structural information of the deposits.

Thermochronology is used in a wide variety of subjects today, such as tectonic studies,[12] exhumation of mountain belts,[13] hydrothermal ore deposits,[4] and even meteorites.