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Geological dating problems

It is also important to note that different mineral geochronometers and thermochronometers can only answer specific questions.

The common pre-conditions for application of these methods are: (1) the source areas are characterized by rocks with different tectonic histories recorded by distinctive crystallization and cooling ages, and (2) the source rocks contain the selected mineral.

Whereas zircons occur in most magmatic, metamorphic, and sedimentary rocks, other minerals, such as apatite, monazite, and white mica, are less abundant.

In principle, any material of plant or animal origin, including textiles, wood, bones and leather, can be dated by its content of carbon 14, a radioactive form of carbon in the environment that is incorporated by all living things.

Because it is radioactive, carbon 14 steadily decays into other substances.

Since 1947, scientists have reckoned the ages of many old objects by measuring the amounts of radioactive carbon they contain.

New research shows, however, that some estimates based on carbon may have erred by thousands of years.

The Lamont-Doherty scientists conducted their analyses on samples of coral drilled from a reef off the island of Barbados.

The samples represented animals that lived at various times during the last 30,000 years. Alan Zindler, a professor of geology at Columbia University who is a member of the Lamont-Doherty research group, said age estimates using the carbon dating and uranium-thorium dating differed only slightly for the period from 9,000 years ago to the present.

The main strength of zircons resides in the fact that they are capable of surviving multiple phases of physical and chemical weathering, erosion, and deposition.

The increased use of multicollector-laser ablation-inductively coupled plasma–mass spectrometry (MC-LA-ICPMS) in recent years is a significant advancement in the application of U-Pb geochronology to provenance and tectonic problems, because the technique can efficiently generate a large number of analyses (Gehrels et al., 2008).

Uranium 234, a radioactive element present in the environment, slowly decays to form thorium 230.