An archaeologically validated protocol for computing obsidian hydration rates from laboratory data

Obsidian hydration at high elevation: Archaic quarrying at the Chivay source, southern Peru

“…Chemical reactions within obsidian slow considerably with colder temperatures, thus, the slow hydration rate is largely expected (Friedman and Trembour, 1983;Stevens, 2005). However, the slow hydration rate could also be caused by chemical properties of Chivay obsidian, such as lower concentrations of intrinsic water (Liritzis, 2006;Rogers and Duke, 2011;Stevenson et al, 2000;Stevenson et al, 1993). In sum, we lack the chemical, climatic and comparative hydration data to determine the ultimate cause of the slow hydration rate at Maymeja.…”

“…We believe this is largely due to the narrow temporal window of quarrying and the general precision associated with OHD (see also Liritzis and Laskarisa, 2011). Errors associated with OHD are generally in the range of 5e25% of the absolute date (Rogers, 2010;Rogers and Duke, 2011), which is probably greater than the span of time represented at the quarrying pit.…”

“…As well, to construct a correction for elevation, more hydrationeradiocarbon pairs are needed from lower elevations. Following the work of Rogers and Duke (2011), we are also exploring the possibility of using induced hydration to see if we can independently derive an estimate for the rate of hydration in Chivay obsidian.…”

Archaeological Age Estimation Based on Obsidian Hydration Data for Two Southern Andean Sources

“…The rate at which water diffuses into glass can be determined by either of two methods: (1) empirically, by assessing the relationship between hydration depth (however it is measured) and the 14 C dates with which the measured samples are clearly associated; or (2) by inducing hydration in a laboratory and calculating a hydration rate based on the activation temperature and Arrhenius equation for reaction kinetics (Friedman and Long 1976;Friedman and Trembour 1983;Rogers 2007;Rogers and Duke 2011;Stevenson and Novak 2011;Stevenson and Rogers 2014). Laboratory-induced rates, while potentially more precise and less timeconsuming, have only recently been shown to reliably predict the ages of artifacts independently dated by radiocarbon or other methods (Ambrose and Novak 2012;Rogers and Duke 2011;cf.…”

“…Laboratory-induced rates, while potentially more precise and less timeconsuming, have only recently been shown to reliably predict the ages of artifacts independently dated by radiocarbon or other methods (Ambrose and Novak 2012;Rogers and Duke 2011;cf. Anovitz et al 1999;Rogers 2006).…”