New obsidian samples (fragments of pebbles and flakes), mixed with ceramic sherds, were found in 10–25 cm cm deep excavations in the Alto Coca Reserve (Napo Province, Ecuador) upon a flat platform on a ridgetop when digging postholes and drainage ditches. Charcoal associated with both obsidian and pottery fragments, attesting to a possible settlement and human pathways (i.e. coluncos), were dated between 1040 and 1210 AD by the AMS radiocarbon (
14
C) method. Representative samples of obsidian found in the Alto Coca Reserve were analyzed by INAA (major elements) and ICP-OES-MS (trace elements), together with four additional obsidian samples collected from the Sumaco Volcano area, located at the same longitude but ca. 45 km to the south. The Sumaco site (dated by radiocarbon between 1398 and 1451 AD) was preliminary investigated by Santi et al. (in J Archaeol Sci 37:1753–1760.
https://doi.org/10.1016/j.jas.2010.01.034
,  
2010
). Major and trace elements analyses of all the samples closely match with obsidian pebbles collected by Knight et al. (in J Archaeol Sci 38:1069–1079.
https://doi.org/10.1016/j.jas.2010.12.002
,
2011
) along the Cosanga River and its tributar...

A pre-Columbian obsidian trade from secondary fluvial sources supported by new geochemical data from the Alto Coca Reserve and Sumaco sites (Napo Province, Ecuador)

10.1007/s12520-022-01527-0