Canyon Creek revisited: New investigations of a late prehispanic turquoise mine, Arizona, USA

Turquoise has been used in the American Southwest since "time immemorial," and remains an important material for contemporary indigenous groups of the region. Detailed studies of ancient turquoise mines are few, however, and inferences of turquoise procurement and provenance have been limited. Our intensive investigation of one mine, the Canyon Creek locale in Arizona, integrates archaeology and geochemistry to enhance understanding of the mine and its output. A detailed description of the mine's morphology and geologic setting lays foundations for interpreting an isotopic analysis of specimens from the mine's four localities. The analysis reveals extremely radiogenic Pb isotope ratios, which distinguish Canyon Creek turquoise from that of other known sources in the American Southwest. Its distinctive isotopic signature makes Canyon Creek turquoise readily identifiable in archaeological assemblages. The presence of turquoise from Canyon Creek at late prehispanic settlements in east-central Arizona helps clarify the mine's chronology of use and regional distribution. Our observations suggest the mine was larger than previously supposed, and that it provided an important source of turquoise for inhabitants of the region during the thirteenth and fourteenth centuries AD. (C) 2017 Elsevier Ltd. All rights reserved.National Science Foundation [BCS 0852270, BCS 1440452]; University of Arizona (School of Anthropology)36 month embargo; published online: 29 September 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Was Aztec and Mixtec turquoise mined in the American Southwest?

Archaeologists have long suggested that prehispanic states in Mesoamerica acquired turquoise through long-distance exchange with groups living in what is now the American Southwest and adjacent parts of northern Mexico. To test this hypothesis, we use lead and strontium isotopic ratios to investigate the geologic provenance of 43 Mesoamerican turquoise artifacts, including 38 mosaic tiles from offerings within the Sacred Precinct of Tenochtitlan (the Mexica or Aztec capital) and 5 tiles associated with Mixteca-style mosaics currently held by the Smithsonian's National Museum of the American Indian. Most of these artifacts have isotopic signatures that differ from turquoise deposits in the American Southwest, but closely match copper deposits and crustal rocks in Mesoamerica. We thus conclude that turquoise used by the Aztecs and Mixtecs likely derives from Mesoamerican sources and was not acquired through long-distance exchange with the Southwest.Florence C. and Robert H. Lister fellowshipOpen access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Isotopic composition of lead white pigments on qeros: implications for the chronology and production of Andean ritual drinking vessels during the colonial era

Abstract For millennia, qeros have been a primary component of ceremonially and politically important toasting rituals in the Andes and retain their cultural significance to this day. These wooden drinking vessels underwent a stylistic and technical revolution in the colonial period (1532–1821 AD). Among an array of features that distinguish colonial qeros from their Inka predecessors is the presence of lead white, a pigment that was introduced to the Andes by the Spanish. Here, we present lead (Pb) isotope measurements of lead white pigments from 20 colonial qeros from the collections of the National Museum of the American Indian, the American Museum of Natural History, the Brooklyn Museum of Art, the Metropolitan Museum of Art, and in a private collection. Although most of the vessels are not known to be associated with one another, their lead white pigments fall into three distinct and internally consistent groupings in Pb isotope space. We interpret the isotopic signatures of two of the groups to indicate that the lead white was imported from Europe. We suggest that the largest grouping (comprising pigments sampled from 12 qeros) is decorated with lead white of Andean origin. These isotopic signatures may have a chronological component, and strongly suggest some form of centralization in pigment acquisition, manufacture, and/or distribution in the colonial period.http://deepblue.lib.umich.edu/bitstream/2027.42/173990/1/40494_2020_Article_408.pd

Mercury contents and isotope ratios from diverse depositional environments across the Triassic–Jurassic Boundary: Towards a more robust mercury proxy for large igneous province magmatism

Mercury is gaining prominence as a proxy for large igneous province (LIP) volcanism in the sedimentary record. Despite temporal overlap between some mass extinctions and LIPs, the precise timing of magmatism relative to major ecological and environmental change is difficult to untangle, especially in marine settings. Changes in the relative contents of Hg in sedimentary rocks through time, or ‘Hg anomalies’, can help resolve the timing of LIP activity and marine extinctions. However, major questions remain unanswered about the fidelity of Hg as a proxy for LIP magmatism. In particular, depositional (e.g., redox) and post-depositional (e.g., oxidative weathering) processes can affect Hg preservation in marine sediments. These factors pose challenges for confidently using Hg as a fingerprint of volcanism. Here, we use the Hg anomaly at the Triassic–Jurassic boundary to explore the opportunities and challenges associated with two approaches that may help build a more robust interpretation of the Hg proxy: (1) measurements from sediments from diverse depositional environments, including lithologies with low Hg and organic carbon content, and (2) the simultaneous use of Hg stable isotope ratios. We present and compare Hg records from five geographically disparate Upper Triassic–Lower Jurassic marine sections that represent nearshore, mid-shelf, deep-water, and carbonate platform settings. These sedimentary sections span the emplacement of the Central Atlantic magmatic province (CAMP) and the associated end–Triassic extinction (ETE). Total organic carbon contents, carbonate contents, and Hg contents and stable isotope compositions demonstrate the multiple ways in which different depositional environments impact how Hg anomalies are expressed in ancient marine sedimentary rocks. Although we observe an increase in Hg/TOC during the ETE in each section, the pattern and duration of Hg enrichment differ notably between sections, and the timing is not always coincident with CAMP activity, illustrating how the depositional filter complicates the use of Hg/TOC ratios alone as a fingerprint of LIP magmatism. In addition, Hg isotope measurements support a volcanic origin for these Hg anomalies during the ETE, suggesting CAMP was the Hg source during the extinction interval. These data support the use of Hg isotopes to help distinguish Hg loading that results from LIP magmatism on a global scale and emphasize the importance of making Hg proxy measurements from diverse depositional environments