Things we gain in the fire. Archaeometric approach of firing temperatures in pre-Hispanic pottery from the Upper Delta of Paraná River (Argentina)

Abstract

In Argentinean Northeast archaeology, few studies address the firing procedures of pre-Hispanic pottery making. Until now, no physical-chemical techniques have been applied to measure the transformations suffered by ceramics during firing. In order to modify this situation, we applied X-ray diffraction, differential thermal and thermogravimetric analysis, and thermal expansion on 31 archaeological ceramic samples recovered at the Los Tres Cerros 1 and Cerro Tapera Vázquez sites (Upper Delta of the Paraná River). Most of the samples (i.e., vessels with a restricted and unrestricted mouth, ‘campanas’ and ‘spoon’) were firing at temperatures above 550/650ºC and below 800ºC; four did not exceed 550/650ºC, and two were subjected to temperatures above 800/900ºC. These results, joined with ethnoarchaeological, experimental, and archaeological evidence, allowed us to read into the wide range of firing temperatures detected (< 550ºC and > 800ºC) as indicative of firing in open structures (i.e., bonfires or pits). In addition, this data allowed us to discuss different firing conditions hypotheses proposed in previous research and to develop an experimental program that will allow us to know different aspects of the pre-Hispanic firing procedures.

Keywords
Archaeological pottery; XRD; DTA-TG; Thermal expansion; Firing