Geochemical signature identifying features and archaeological structures in eastern Amazonian Terra Preta sites

Abstract

The present work describes the chemistry and mineralogy of soils such as Terra Preta Arqueológica (TPA) or Terra Preta de Índio (TPI) from the Bitoca I and II sites, located in the Salobo Region (Carajás Mineral Province, Pará-Brazil). The results revealed chemical and mineralogical characteristics that are similar to other TPAs found throughout the Amazon region, such as relatively high levels of Ca (average of 3600 ppm), P (average of 850 ppm), Mn (average of 730 ppm), Zn (average of 55 ppm), and Cu (average of 63 ppm). In soils related to the characteristics of occupation by huts and campfires, the mineralogical composition is represented by quartz, kaolinite, calcite, muscovite, anatase, hematite, goethite, and gibbsite. Amorphous phases have also been identified mainly as calcium phosphates and organic matter (humic and fulvic acids). The analysis of the features/structures described here helped in the identification/verification of areas destined for different activities within the sites.