XRF obsidian analysis from Ayacucho Basin in Huamanga province, south-eastern Peru

Abstract

Obsidian was broadly used along the Andean Cordillera in South America. Particularly in Peru, its use can be traced to the earliest human occupations, continuously through pre-Columbian times to contemporary Andean agro-pastoralist societies. In order to distinguish the provenance of obsidians from Peru, this paper reports a new X-ray fluorescence (XRF) analysis on several obsidians obtained in surface collections of the Ayacucho region. The analysis and source determination were made by XRF on 52 specimens. The source assignments involved comparisons between the compositional data for the specimens and the University of Missouri Research Reactor (MURR) XRF obsidian database for sources in Peru. After analysing the samples, obsidian sources were recognized and documented. All had small nodules not larger than about 4 cm. They were recovered from Ñahuinpuquio and Marcahuilca hill which belonged to the previously identified Puzolana source. Another identified source was the well-known Quispisisa, located 120 km south of the city of Ayacucho, and distributed through a vast region in central Peru. The results expand previous observations made on the obsidian provenance at Ayacucho Basin, as well as the extension of the Puzolana source between Yanama and Huarpa hills, south of Ayacucho city.