Petrographic and techno-typological analysis of lithic artifacts from the Pikimachay cave (Pacaicasa and Ayacucho phases)

Abstract

The Pikimachay cave (Ayacucho, Peru), revealed lithic artifacts, bones, and hearths in superimposed strata in two phases: Pacaicasa and Ayacucho. Problematic radiocarbon samples indicated that these occupations date to the Terminal Pleistocene and the lithic artifacts were inadequately documented.

A brief preliminary study is reported, based on a small lithic collection from both phases housed at the MNAAHP, in order to evaluate the anthropogenic character of the samples. Our research aims three objectives, namely: 1. anthropic discrimination, 2. technotypological test and, 3. outline of the chaîne opératoire. This study also presents, for the first time, a mineralogical/petrographic examination of a selection of rock samples from both phases and their potential to evaluate their manufacture.

The analyses show that the specimens from the Pacaicasa phase correspond to granitic igneous, microporphyritic igneous, granodioritic igneous and basic andesite igneous rocks that are not suitable for carving and do not show negatives. On the contrary, the samples from the Ayacucho phase (ca. 14 kyr) of silicified volcanic rocks with semi-fluid textures, are ideal for knapping, in addition to display clear evidence of intentional reduction (e.g. flakes removed by bifacial knapping), and correspond to areas external to the cave, i.e. they were transported.