Obsidian Sources and Source Provenance of Archaeological Obsidian in Northern Sonora: The Known and Unknown

Abstract

A recent obsidian provenance study in three sites in the Valle de Altar region of northern Sonora has greatly expanded our understanding of the prehistoric relationship between the southern and northern Sonoran Desert. Based on obsidian source provenance, archaeological sites in the Valle de Altar indicate that contact with the region as far north as west-central and northern Arizona, the northern portion of the Papaquería, the Sierra Pinacate, the Sierra Madre Occidental, and the Basin and Range of Chihuahua was potentially frequent. However, the vast majority of artifacts produced from obsidian were procured apparently locally from an, as yet, unlocated source called here “SON Valle de Altar Unknown.” The purpose here is to discuss the relevant regional geology, the source provenance of the obsidian artifact assemblage, and relationships throughout the greater Sonoran Desert. This project also adds significant data to the Southwest Archaeological Obsidian Project (http://swxrflab.net/).

Un estudio reciente sobre procedencia de fuentes de obsidiana en la región del Valle de Altar en el norte de Sonora ha ampliado de manera considerable nuestra comprensión de la relaciones Prehispánicas entre el norte y el sur del Desierto de Sonora. Con base en la procedencia de artefactos elaborados en obsidiana, los sitios arqueológicos del Valle de Altar indican que los contactos dentro de la región se dieron hacia el norte hasta el centro oeste y norte de Arizona, hacia la porción norte de la Papaguería, la Sierra Pinacate y hacia la Sierra Madre Occidental, siendo potencialmente frecuente hasta la Cuenca y cordillera de Chihuahua. Sin embargo, la gran mayoría de los artefactos en obsidiana de esos sitios, fueron producidos a partir de una fuente aparentemente local, aún no localizada, llamada aquí “SON Valle de Altar Desconocida.” El propósito de este artículo es discutir la geología regional, la fuente de procedencia del conjunto de artefactos en obsidiana, así como las relaciones existentes dentro del gran Desierto de Sonora. Este estudio también agrega datos significativos y valor interpretativo al Proyecto Arqueológico de Obsidiana del Suroeste (http://swxrflab.net/swobsrcs.htm).

KEYWORDS:

• Obsidian source provenance
• valle de altar
• social networks
• sonoran desert

Acknowledgments

Thank you to Drs. Elisa Villapando and Randall McGuire for the opportunity to participate in a very much need obsidian provenance project, Elisa for translating my English abstract, and Hunter Claypatch for extending the invitation to modify my obsidian provenance report for this volume. While obsidian provenance studies north of the border have been ongoing for decades, the same is not true for northern Sonora, indeed northwest Mexico overall. My colleagues in northwest Mexico have been the most welcoming colleagues and I look forward to more collaboration in the future. Many thanks to Randy McGuire for facilitating funding for this project at my laboratory. It is greatly appreciated. Finally, thanks to the three anonymous Kiva reviewers for comments that improved the paper.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Data Availability Statement

All source data for this study, indeed all source data for the known sources of archaeological obsidian in the North American Southwest are at the web portal http://swxrflab.net/swobsrcs.htm, and have been since 1995.³ The data table for assigning all the artifacts to source is available in the Shackley Supplement to this Kiva paper, including the trace element data for the archaeological samples (Shackley Supplement Table 1), the analysis of the USGS RGM-1 rhyolite standard (Shackley Supplement Table 2), and the light element oxide values for one of the SON Valle de Altar Unknown samples (Shackley Supplement Table 3). There are also a number of bivariate plots of the archaeological and some source data and a total alkali-silica (TAS) plot of the one SON Valle de Altar Unknown sample located in the Shackley Supplement.

Supplemental Materials

For supplementary material accompanying this paper, visit https://do.org/10.1080/00231940.2024.2340909.

Notes

1 The data from the analysis as well as plots of the data will be in “Shackley Supplement 1” in order to save printed space. The alphanumeric number sequence for the unknown obsidian sources detected in the analysis follows the sequence begun in the project sites in the northern Gulf of California and separate from the unknown sources detected in Sonora to the southeast (Shackley 2019a, 2023a). The one unknown source identified, SON Valle de Altar Unknown was so common that I assigned a distinctive term.

2 Recently, a new source was located near the bend of the Rio Sonora, called El Colorín Jacota, but is not present in these project sites (see Figure 1 herein; Shackley 2019a).

3 Analytical Methodology and Data Depository: All samples in this study were analyzed at the Geoarchaeological XRF Laboratory, Albuquerque, New Mexico (http://swxrflab.net/). The instrument used is a laboratory ThermoScientific Quant'X EDXRF instrument. The instrumental method has been discussed elsewhere in print (Shackley 2005; Shackley et al. 2016), and is available online (http://swxrflab.net/anlysis.htm). Source data is available at the Geoarchaeological XRF Laboratory web portal for all known and reported obsidian sources in the North American Southwest: http://swxrflab.net/swobsrcs.htm, and most lab reports since the mid-1980s are available at the University of California's open source web portal escholarship.org.