Comments on various geospeedometers

Based on the above discussion on various geospeedometers, a rock contains many clues from which its thermal history may be read. Some of these processes, such as homogeneous reactions and diffusion, are simpler and better understood, and hence can be more easily quantified as geospeedometers. Other processes are more complicated, and information stored by those remains to be deciphered. Often the more complicated processes may store more information on the thermal history. 

The geospeedometer based on the kinetics of interconversion of hydrous species in rhyolitic melt is also well developed although the reaction mechanism and rate law are not known. The empirical calibration covers a cooling rate range of 50 Klyx to 100 K/s, about eight orders of magnitude. Theoretically, this 

Complicated heterogeneous reactions may contain the most information on the thermal history of a rock. Currently, few such reactions have been quantified as geospeedometers because rates of such reactions are more difficult to evaluate. Nonetheless, future development of kinetic theory may demonstrate the rich resources in the kinetics of such reactions and the possibility to infer complex thermal history from such reactions. 

The cosmogenic nuclide is unstable and decays into with a half-life of 5730 years (X = 0.00012097 yr ). The initial activity of in a newly formed plant tissue is 1 3.56 dpm per gram of carbon (dpm = decays per minute), and in the year of 2000 you measured activity for a piece of tree tissue from the center of a tree and found that it is 12.8 dpm. 

2 The following table gives measured and °Th activities as a function 

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