Racemization dating method Naked xxx new 01 01 2014 photo

A whole emu egg, with infilling sediment believed to be coeval with egg laying and burial, was found in late Pleistocene lunette sediments near Lake Eyre, central Australia.

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Resolution depends on the average temperature: warmer sites have better resolution and less overall time range.

As a rule of thumb, sites with a mean annual temperature of 30°C have a maximum range of 200 ka and resolution of about 10 ka; sites at 10°C have a maximum age range of ~2 m.y., and resolution generally about 20% of the age; at -10°C the reaction has a maximum age of ~10 m.y., and a correspondingly coarser resolution.

Because the rate of amino acid racemization is controlled by the temperature experienced by the fossil since burial (rather than when it was living), an evaluation of site temperature is required for geochronological interpretation.

It is particularly useful for fossiliferous deposits beyond the range of 14C dating (older than about 40,000 years), for which few alternative geochronological tools are available.

The technique is inexpensive, rapid, and can be applied to fossils as small as single ostracode or foraminifer test.

Amino acid racemization (or ) in fossils is interpreted in terms of relative ages.If the reaction rate can be calibrated using an independently dated nearby site with similar thermal history, absolute dates can be inferred through calibration.All methods agreed within their respective dating uncertainties confirming the utility of all four methods.They indicate an age for the emu egg of 31.24 ± 0.34 ka.Amino acid geochronology is best suited as a relative-dating tool, or as a calibrated-dating method in conjunction with other dating techniques.It is applicable to a wide range of fossils types (mollusks, ostracodes, foraminifera, bone, egg shells, and teeth), stratigraphic problems (correlations, reworking, unconformities), depositional environments (marine, lacustrine, fluvial), and time scales (decades to millions of years).

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