Advances in the Hydration Dating of New Zealand Obsidian

Stevenson, Christopher M.; Sheppard, Peter; Sutton, Douglas G.; Ambrose, Wallace

doi:10.1006/jasc.1996.0020

Cited by 21 publications

(13 citation statements)

References 12 publications

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“…with respect to the local structures of type III, IV, and V glasses, the coordination number of Zr has a positive correlation with the temperature. With regard to the density of type II-IV glasses, obsidian has an average density of 2.36 g/cm 3 (Stevenson et al, 1996), while the average density of tektite is 2.4 g/cm 3 (Dunlap et al, 1998). Further, that of Darwin glass is 2.45-2.55 g/cm 3 (Fudali and Ford, 1979).…”

Section: Discussionmentioning

confidence: 97%

XAFS study on the Zr local structures in tektites and natural glasses

Tobase

Yoshiasa

Hongu

et al. 2015

Journal of Mineralogical and Petrological Sciences

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The local structures of tektites and natural glasses were studied by Zr K-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements in order to obtain quantitative data on the Zr-O (bonding) distances and coordination numbers for the glasses. Zr 4+ ions have different coordination environments. The structure of glass (tektite, impact-related glass, fulgurite, and volcanic glasses) is affected by the temperature during the glass-formation process. Differences in the formation processes for natural glasses result in different local structures for the zirconium ions.All tektites can be classified as being of the same type and as having 7-fold coordination Zr ions. The Zr-O distances in tektite glasses are 2.198-2.215 Å, and their XANES spectra are similar, too. Impact-related glasses can be classified into different types and are formed under different physical and geological processes at the impact event. Volcanic glasses, impact-related glasses, and fulgurite glasses have several local Zr structures with 6-and 7-fold coordinated Zr ions. It can thus be concluded that local structures of Zr in natural glasses are closely related to the formation temperature and quenching conditions of the glasses. The Zr XAFS spectra of natural glasses can be used to identify the naturalglasses.

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Section: Discussionmentioning

confidence: 97%

XAFS study on the Zr local structures in tektites and natural glasses

Tobase

Yoshiasa

Hongu

et al. 2015

Journal of Mineralogical and Petrological Sciences

View full text Add to dashboard Cite

show abstract

“…Monteith, 1975;Campbell, 1977Campbell, , 1985Hanks & Ashcroft, 1980;Rosenberg, Blaine & Shashi, 1983;Oke, 1987;Ayra, 1988;Monteith & Unsworth, 1990;Stoutjesdijk & Barkman, 1991) to establish a baseline for the study of the archaeological soil climate. (Stevenson et al, 1995;Stevenson, pers. comm.…”

Section: Effective Hydration Temperature Estimationmentioning

confidence: 96%

“…As an example we can see that for a typical Mayor Island obsidian (Stevenson et al, 1995) hydrating for 1000 years at an EHT of 17 C, an estimated EHT of 17·5 C corresponds to a calculated date of 941 years or a date error of around 6%. A more usual scenario is that the EHT would be estimated as temperature range; for example 17 C 0·4 .…”

Section: Obsidian Hydration Dating and Temperaturementioning

confidence: 98%

“…This means that the dating error associated with any temperature estimation error is specific to each particular obsidian. For example, in Table 1 a typical Great Barrier obsidian (Stevenson et al, 1995) hydrating for 1000 years at an estimated temperature of 17 C 0·4 generates a corresponding date range of 1048-954 years, or a 9·4% date error range, in comparison to the 9·8% error range for the Mayor Island obsidian. Therefore it is necessary to calculate the dating errors associated with an EHT estimation for each artefact explicitly.…”

Section: Obsidian Hydration Dating and Temperaturementioning

confidence: 99%

“…A ttempts to reduce errors in obsidian hydration dating have focused on improving hydration rim measurement and the estimation of glass hydration rates ( Lee et al, 1974;Ambrose, 1976Ambrose, , 1993Freidman & Long, 1976;Lowe, 1977;Tsong et al, 1978;Leach & Naylor, 1981;Duerden, Cohen & Ambrose, 1982;Michels, Tsong & Smith, 1983;Kondo & Matsui, 1992;Mazer et al, 1992;Stevenson et al, 1993Stevenson et al, , 1995. Comparatively little experimental work has been carried out on soil or storage temperature (Freidman, 1976;Ambrose, 1980Ambrose, , 1984Freidman & Trembour, 1983;Leach & Hamel, 1984;Stevenson, Carpenter & Scheetz, 1989), although ambient soil temperature is one of the principal variables governing the rate at which obsidian hydrates (Freidman & Smith, 1960).…”

Section: Introductionmentioning

confidence: 99%

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