A geochemical baseline for clays of the Toluca Valley, Mexico

Abstract This paper presents the results of the INAA of 28 geological clay samples from the Toluca Valley (Upper Lerma) in the State of Mexico, Mexico and the immediately adjacent areas to the north, west, and south. While preliminary, these results demonstrate that there are internal elemental clines within the Toluca Valley, based on elevation (Na, K) and latitude (Cr), among other patterns. These samples also demonstrate that the underlying geology of the Toluca Valley can be systematically differentiated from that of the adjacent Basin of Mexico based on higher Ba and lower K concentrations. This study confirms the results of prior analyses of archaeological ceramics from the Toluca Valley, and provides new avenues for dividing the region into multiple sub-regional source areas in future archaeological analyses.