Osl dating method

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All sediments and soils contain trace amounts of radioactive isotopes of elements such as potassium, uranium, thorium, and rubidium.These slowly decay over time and the ionizing radiation they produce is absorbed by mineral grains in the sediments such as quartz and potassium feldspar.This is caused by a number of factors, including variations in solar radiation, magnetic storms, and internal geophysical factors.Unconsolidated sediments contain magnetic minerals, such as those on the continental shelf and slope. The remnant magnetism of the sediment is a reflection of the earth’s palaeomagnetic field at the time of deposition.It includes techniques such as optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and thermoluminescence dating (TL).

This is because the earth’s magnetic field varies in strength and polarity direction.Stimulating these mineral grains using either light (blue or green for OSL; infrared for IRSL) or heat (for TL) causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral.Most luminescence dating methods rely on the assumption that the mineral grains were sufficiently "bleached" at the time of the event being dated.This information is vital for numerical models, and answers questions about how dynamic ice sheets are, and how responsive they are to changes in atmospheric and oceanic temperatures.Unfortunately, glacial sediments are typically difficult to date.

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