The Selene Obsidian Source (Formerly Sonora Unknown B) of the Upper Río Bavispe Basin, Sonora, Mexico

Abstract

An energy-dispersive X-ray fluorescence (EDXRF) analysis of nineteen obsidian source rocks from a mid-Tertiary rhyolite/perlite flow in the upper Río Bavispe basin of northeastern Sonora, Mexico solves the location of “Sonora Unknown B” as reported by ) for recent archaeological projects in northeastern Sonora and southeastern Arizona. This newly discovered source, called Selene, is a relatively large marekanite source consisting of a very high-silica rhyolite with regionally distinct high barium (Ba) and strontium (Sr) values, and low zirconium (Zr) elemental concentrations. The Selene nodules are relatively large compared to nodules from other northern Sonoran and Chihuahuan obsidian sources, and have excellent knapping qualities. We believe these attributes contributed to the transport, trade, and use of Selene obsidian hundreds of kilometers from the source. This is in contrast to marekanites from some other sources in northwestern Mexico, which were at most transported and used a few tens of kilometers from their sources (; :77).