|Title:||Volcanic ash provenance from zircon dust with an application to Maya pottery|
|Authors:||K. T. Coffey, A. K. Schmitt, A. Ford, F. J. Spera, C. Christensen, and J. Garrison|
|Publication:||Geology, v. 42, p. 595‐598.|
|Publish Date:||July 2014|
When analyzed using secondary ion mass spectrometry, dust‐sized (<63 µm) zircon in distal ash deposits of the Tierra Blanca Joven (TBJ) eruption of Ilopango Volcano (El Salvador) yielded results consistent with ages obtained from those in proximal deposits. This finding indicates insignificant age sorting of zircon crystals during their dispersal in the TBJ ash plume. As a result, analysis of zircons may permit reliable source identification of distal tephra marker beds commonly found in terrestrial and marine environments. This technique was applied to test whether an enigmatic volcanic ash used to manufacture Late Classic Maya pottery from El Pilar is from distal TBJ ash deposits, a hypothesis supported by the location, extent, and timing of the TBJ eruption, and the matching high silica content and trace element ratios between TBJ glass and glass in the archaeological samples. The exclusively older than 1 Ma ages of the archaeological zircons compared with the dominantly ca. 0‐30 ka ages of the TBJ zircons, however, rule out the TBJ eruption as the source of the pottery ash. The three analyzed archaeological pottery samples define two distinct zircon age distributions, indicating that the ash in the Maya pottery must be from multiple sources, which currently remain unidentified.