Magnetic signature of deep pit ovens from Paquimé, ceremonial center of the Casas Grandes culture (Northern Mexico)

The Casas Grandes culture in Northern Mexico and Southwest United States has been characterized by its impressive architecture - unique to desert cultures, with houses and constructions of up to four floors built by adobe. In this study, we report an integrated rock-magnetic and archaeomagnetic study from Paquimé archaeological site, considered as an outstanding testimony of the relationship between the cultures of North America and Mesoamerica. The In Situ structures of Paquimé archaeological zone were magnetically analyzed for the first time. Four up to 2.6 m deep Pit Ovens, commonly used for agave cooking, were sampled. 78 specimens were subjected to stepwise alternating field demagnetizations to retrieve characteristic remanence archaeodirections. The great majority of samples yielded evidence of essentially stable, single component remanent magnetization carried by the end members of titanomagnetite solid solutions (almost magnetite phase). Hematite grains apparently also co-exist, but their contribution in total thermoremanence is minor. The archaeomagnetic dating, based on mean declination and inclination, was performed using the global geomagnetic models and the available regional Paleosecular Variation Curves available for Mesoamerica. Additionally, SW United State paleosecular variation patterns from Four Corner region was also considered. The most probable age interval for one of the studied ovens (around 940 AD) is out of Paquimé’s main occupation phase between 1200 and 1450 AD. The age estimation for the PH1 pit oven, around 1150 AD, could be located near the limit of the beginning of the Medio Period. Remained two analyzed ovens yielded up to three possible ages distributed around 1100, 1320 and 1480 AD. Pit Ovens studied here, were long time considered to correspond to same time interval, while these new results attest that these combustion structures encompassed almost six centuries in agreement with the historical fact that the city of Paquimé was abandoned before the arrival of the Spaniards.