S-T Laboratory
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QUATERNARY
GEOCHRONOMETRY
Dear colleagues,

Our group has been working in the sphere of TL dating of Quaternary sediments from the beginning of the 70s. Almost at once we faced the fact that reasonable results took place no more than for half of samples. The second half showed so incorrect dates that it could not be explained from the viewpoint of known problems. Then we concentrated our activity on detailed research of the TL phenomenon of natural quartz as the basic mineral used in TL geochronometry for searching other unrecognized reasons of such a phenomenon.

In the middle 80s we found the reason capable of leading to the error up to 300 % and more. This reason consisted in a great difference of a mineral behavior as a dosimeter under artificial irradiation which was applied to model its behavior as a palaeodosimeter under influence of natural background radiation. Simultaneously we found a method of TL dating without using artificial irradiation. We named this method as “S-S dating”. Exception of a complex procedure of artificial irradiation enabled to carry out wide tests of the new method in short terms. As a result we received a great set of dates with spatio-temporal coordination in the vast territory of Eastern Europe.

The only one but a big defect of “S-S dating” was a restriction of its applicability only by regions with special geological conditions. The new updating named as “S-T dating” solved the problem of this restriction only in part.

The basic complexity of all versions of optical dating, including our both methods, is connected with wide dispersion of mineral optical properties. This dispersion leads to necessity of their individual calibration used in traditional methodical direction. The same reason limited our opportunities only to those provinces in which quartz showed identical optical properties.

We could solve the problem of regional restriction only in 2002. It became possible due to refusal to use luminescent energy as a criterion of a sample age. We replaced it by measurement of temperature of luminescence maximum of a sample during its heating. This characteristic point has a distinctly expressed shift with change of light energy and can be used as independent information on a sample age. Thermophysical properties of minerals are many times more stable than optical ones, so the trend curve of peak's maximum depends neither upon conditions of formation of a mineral nor upon its subsequent history. In other words this curve has a global invariance.

We have named the latest method as “T-T dating”. It keeps all advantages of the “S-S” and “S-T” prototypes in terms of simplicity and high efficiency but it has no regional restrictions inherent in the prototypes.

Dear students,
I am looking among you for some persons who would like to continue our direction in the problem of Quaternary chronometry. I have no doubt that our way is very perspective.

Yours faithfully,
Alexander Shlukov