Obsidian hydration dating limitations
Water vapor pressure may also affect the rate of obsidian hydration.
The reliability of the method based on Friedman’s empirical age equation (x²=kt, where x is the thickness of the hydration rim, k is the diffusion coefficient, and t is the time) is questioned from several grounds regarding temperature dependence, square root of time and determination of diffusion rate per sample and per site, apart of some successful attempts on the procedure and applications.
SIMS in general refers to four instrumental categories according to their operation; static, dynamic, quadrupole, and time-of-flight, TOF.
In essence it is a technique with a large resolution on a plethora of chemical elements and molecular structures in an essentially non destructive manner.
This latest advance, the novel secondary ion mass spectrometry–surface saturation (SIMS-SS), thus, involves modelling the hydrogen concentration profile of the surface versus depth, whereas the age determination is reached via equations describing the diffusion process, while topographical effects have been confirmed and monitored through atomic force microscopy.
Several factors complicate simple correlation of obsidian hydration band thickness with absolute age.
The hydration rind is then measured under a high-power microscope outfitted with some method for measuring distance, typically in tenths of micrometers.
The technician measures the microscopic amount of water absorbed on freshly broken surfaces.
Search for obsidian hydration dating limitations: