¹⁴C-AMS IN MEXICO AND PRE-COLUMBIAN ARCHAEOLOGY

Abstract

The complex geographical scenario of Mexico allowed the cultural diversification and development of multiple cultures such as Tolteca, Teotihuacan, Mexica, and Maya, among others. Despite this rich cultural heritage, radiometric dating of Mexican cultural samples with radiocarbon (14C) began only in the 1980s and with accelerator mass spectrometry (AMS) in 2013. Analysis of 14C with AMS is the most widely used technique to date archaeological objects and cultural heritage. Since 2013, the Accelerator Mass Spectrometry Laboratory (LEMA) facility of the Institute of Physics at UNAM (IF-UNAM) has supported archaeological research in Mexico, but also investigation in other areas such as geology, physics, chemistry, and environmental sciences through the analysis of 14C, 10Be, 26Al, 129I, and Pu. The absolute dating with 14C continues to be the core of LEMA’s work, where different geographical scenarios of the country and climatic conditions present very diverse analytical challenges. This work presents a basic description of the AMS system of the LEMA laboratory and describes some applications that are currently being developed.

Refining Ceramic Chronology and Epiclassic Reoccupation at La Ventilla, Teotihuacan Using Trapezoidal Bayesian Modeling

“…The Early Xolalpan sequence in this model is more precise than the Tlamimilolpa sequence and assists in explaining why the end date for the Tlamimilolpa phase is closer to AD 400. The modeled 14 C dates from La Ventilla indicate that Early Xolalpan was a relatively short ceramic phase lasting from approximately cal AD 400 to 450. Recent chronologies place the beginning of this ceramic phase earlier, at AD 350 (e.g., Cowgill 2015).…”

“…Only adult individuals (>15 years of age) were sampled in this study to obtain adequate bone collagen yields for 14 C measurements. Bone collagen samples from 78 individuals from LV1 (N = 3), LV2 (N = 18) and LV3 (N = 57) were processed for AMS 14 C dating at the Human Paleoecology and Isotope Geochemistry Laboratory at The Pennsylvania State University. The surfaces of all bone samples were first manually cleaned with an X-ACTO ® blade.…”

“…Finally, due to the large number of secondary burials within this population, we have combined all measured 14 C dates across the three compounds to reconstruct the occupational history of the La Ventilla neighborhood as a whole. The ceramic phases for each burial analyzed in this study were assigned by Serrano Sánchez ( 2003) for LV1 and LV2 and by G ómez Chávez (2000) and Clayton (2009) for LV3.…”

“…Burial 26, located in the Red Borders plaza of LV1 and associated with a Coyotlatelco red-onnatural ring-based bowl, is the earliest-dating Coyotlatelco primary burial, with a median 14 C date of cal AD 565 (Table 2). Burial 27, with a median 14 C date of cal AD 585, is the earliestdating primary burial representing this phase in LV2 and was associated with an array of Coyotlatelco-style potsherds near the interment.…”

THE FIRST 14C LABORATORY IN MEXICO: THE BASIS OF A NEW RELATIONSHIP BETWEEN PHYSICISTS AND ARCHAEOLOGISTS

“…The First 14 C Lab in Mexico 627 radiocarbon analysis and sample preparation (Solís et al 2014). With this new facility, the IF has contributed to establish the occupation chronology of some of the pre-Columbian cultures throughout Mexican territory (G ómez-Chávez et al 2017;Solís et al 2017Solís et al , 2020Balcells et al 2019;Alcántara et al 2020). One example is the Mayan Codex of Mexico, dated at LEMA and considered the oldest document in the Americas (Solís et al 2018(Solís et al , 2021.…”