Rehydroxylation dating

Hare, V

Abstract:: This thesis is concerned with a better understanding of issues which currently limit the precision, accuracy and robustness of rehydroxylation (RHX) dating. MC simulations and analytical expressions show that age uncertainties of previous studies are underes- timates. The ratio of sample mass to balance resolution should be of the order of 10⁻⁶ or less for measurement precision under 1%. A combined measurement uncertainty of ∼ 4 % should be possible, given well-designe...
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APA Style

Hare, V. (2016). Rehydroxylation dating [PhD thesis]. University of Oxford.

MLA Style

Hare, V. Rehydroxylation Dating. University of Oxford, 2016.

Chicago Style

Hare, V. 2016. “Rehydroxylation Dating.” PhD thesis, University of Oxford.
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Files:: Hare_DPhil_Dissemination.pdf

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Authors

+ Hare, V More by this author

Division:: SSD
Department:: School of Archaeology
Role:: Author

Contributors

+ Ramsey, C

Role:: Supervisor

+ Hall, C

Role:: Examiner

+ Pollard, A

Role:: Examiner

+ Clarendon Fund More from this funder

Funding agency for:: Hare, V

+ John Fell OUP Research Fund More from this funder

DOI:: 10.5287/ora-4jdn99je9
Type of award:: DPhil
Level of award:: Doctoral
Awarding institution:: University of Oxford

UUID:: uuid:3bf6753e-77b7-4a69-8cd6-e6a4c319fa09
Deposit date:: 2018-01-18

Related item:: Testing the (time)1/4 diffusion law of rehydroxylation in fired clays: evidence for single-file diffusion in porous media?
Description:: Fired clay minerals rehydroxylate after firing, a phenomenon that causes the long-term mass gain and expansion seen in archaeological ceramics. During rehydroxylation, fired clay minerals react with H2O to form structural hydroxyl (OH). Recent models propose that rehydroxylation is described by a quartic root (t1/4) time dependence, which has led to a dating method based on the process (RHX, rehydroxylation dating). The time dependence has been interpreted as an indication of a transport process of single-file diffusion of H2O molecules along restricted pathways in clay mineral, as theory predicts that the associated root mean square displacement is proportional to t1/4. However, dating trials have led to alternative models, and the process is still poorly understood. Here we outline currently outstanding problems found in different experimental studies, and propose novel ways of investigating the phenomenon. These include (i) gravimetric analyses using pure clay ceramics which are free of calcite and other minerals, and reducing cooling effects by using thin samples; (ii) highresolution nuclear magnetic resonance (NMR) with aluminum and silicon as well as with protons (hydroxyls, water) for exploring structure and dynamics, and pulsed field gradient (PFG) NMR for exploring water/proton diffusivities; (iii) IR spectroscopy, and micro-IR imaging to explore the spatial-temporal dependence of rehydroxylation of fired clay and (iv) structural investigations by high-resolution electron microscopy and X-ray diffraction.
Related item:: Theoretical constraints on the precision and age range of rehydroxylation dating
Description:: Accurate and precise dating methods are of central importance to archaeology, palaeontology and earth science. This paper investigates the expected precision and age range of rehydroxylation dating, a recently proposed technique for fired clays. An expression for combined measurement uncertainty is presented, which takes into account all significant sources of experimental uncertainty. Numerical simulations are performed for comparison. Combined measurement uncertainties of approximately 5% with respect to the age of the ceramic should be possible given well-designed experiments. In this case, the most significant contribution to combined measurement uncertainty is from effective lifetime temperature. In addition, it is shown that precision should be acceptable for recently fired material (less than 1 year). Mismatch of balance resolution to sample mass results in large variation in combined relative uncertainties, which vary by four orders of magnitude (approx. 1–1160%) across recent experimental studies, rendering some recently reported dates meaningless. It is recommended that this ratio be less than 10−6 for a combined relative uncertainty of less than 1%. The age limits of the technique are set by the value of the rate constant and individual sample mineralogy. This theoretical framework should help future interlaboratory comparison as well as optimizing instrument design.

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Copyright holder:: Hare, V

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Rehydroxylation dating

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