Obtaining accurate age determinations from minerals in archaeological ash is a major unsolved issue in radiocarbon (14C) dating. This is because the original14C content of calcite, the main component of ash, is altered by isotopic exchange. Pyrogenic aragonite, another mineral phase recently discovered in ash, might preserve its14C signature through time. Using a new method based on density separation and step combustion, we were able to isolate and date aragonitic ash from an archaeological destruction horizon of known age. Here we show that the14C age of aragonite matches the age of the destruction horizon. Our results demonstrate that pyrogenic aragonite is a short-lived material suitable for14C dating and directly related to human activities involving the use of fire, thus bearing major implications for the establishment of absolute chronologies for the past 50,000 yr.
Bibliographical noteFunding Information:
This research was funded by the Alexander von Humboldt Foundation through postdoctoral fellowship to Michael Toffolo, which included a Europe Research Stay at the Weizmann Institute of Science. Part of the FTIR measurements were performed on instrumentation funded by a grant from the Deutsche Forschungsgemeinschaft (MI 1748/1-1). Sample preparation for 14C dating was funded by the Exilarch’s Foundation for the Dangoor Research Accelerator Mass Spectrometer and by the Max Planck-Weizmann Center for Integrative Archaeology and Anthropology. Micromorphological analysis was conducted by RSG at the Kimmel Center for Archaeological Science, Weizmann Institute of Science. The authors are grateful to Israel Finkelstein and MarioMartin, co-directors of theMegiddo Expedition, for granting access to the site, and to Heinrich Taubald for performing stable isotopes analysis. CB wishes to thank Frieder Lauxmann for performing μ-Raman measurements. MBT wishes to thank Francesca Strappini for her continued support during laboratory analyses and writing, Steve Weiner and Yotam Asscher for useful discussions, and Ilit Cohen-Ofri for assistance during TGA analysis.
© 2017 by the Arizona Board of Regents on behalf of the University of Arizona.
- Density separation
ASJC Scopus subject areas
- Earth and Planetary Sciences (all)