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  • Thumbnail for The ethno-geology of Shiprock, Navajo Volcano Fields, New Mexico
  • Thumbnail for Obsidian artifact provenance study of the Piedras Marcadas Pueblo, Albuquerque, New Mexico
    Obsidian artifact provenance study of the Piedras Marcadas Pueblo, Albuquerque, New Mexico by Freeman, Alexandra

    This study conducts provenance research on 65 artifacts from the Piedras Marcadas (PM) Pueblo in Albuquerque, New Mexico. Late Tertiary and Quaternary eruptions prompted by regional continental extension, associated with the formation of the Rio Grande Rift and volcanism of the Jemez Lineament, produced a number of obsidian-bearing rhyolitic units from several major volcanic fields in western New Mexico that are relevant to this study. Obsidian nodules were collected from the two most proximal volcanic provinces, the Jemez and Mount Taylor volcanic fields, to the PM site for geochemical comparison to the subsurface artifacts. Archived data for three sources in the Jemez Mountains (Canovas Canyon, Paliza Canyon, and El Rechuelos Rhyolite) and two sub sources of the Taos Plateau (No Agua Peaks North and West) were also used for comparison. Trace element data were collected on each sample using energy dispersive X-ray fluorescence spectrometry (ED XRF). The chemical relationship between each obsidian flake artifact and all source chemical groups was analyzed on bivariate plots comparing trace element concentrations of Y, Nb, Rb, Zr, and Sr using the SPSS program. Cluster analysis paired with T –test verification, using the Minitab program, successfully correlated each artifact to its corresponding geologic source of origin. Comparison between geochemical signatures of 9 sources and 62 artifacts identified 53 Cerro Toledo, 4 Canovas Canyon, 3 Valles, 1 Paliza Canyon, and 1 El Rechuelos artifacts. Three outlier samples are non-obsidian. The dominance of Cerro Toledo obsidian in the artifact samples directly relates to proximity and availability of Cerro Toledo nodules in Rio Grande alluvium, found adjacent to the PM site. The water-worn physical condition of the Cerro Toledo nodules suggests secondary sources played a major role in distributing and providing closer obsidian sources for the PM pueblo. The presence of three Valles Rhyolite obsidian samples provides evidence for procurement from the primary source in the Valles Caldera, as the source occurs in minor abundance and sizes in Rio Grande river deposits. The absence of Mount Taylor artifacts suggests that the PM pueblo did not interact with the Zuni pueblo who controlled Mount Taylor region at the time when the artifacts were deposited.