Micromorphology of Archaeoanthrosols from limestone rock-shelters in Peruaçu-Minas Gerais, Brazil: Insights on soil genesis

ABSTRACT The occurrence of late Quaternary archaeological sites in shelters is fundamental for understanding Brazilian pre-Columbian human occupation along the São Franciscan depression, requiring cooperative efforts between professionals in Archaeology, Pedology, Biology and Anthropology. The present interdisciplinary study aimed to characterize Archaeoanthrosols in natural limestone shelters in the Peruaçu National Park, in the northern region of Minas Gerais. Pre-Columbian people inhabited these shelters for thousands of years, leaving materials of different natures and origins, resulting in very peculiar anthropogenic soils, on which no pedo-archaeological studies have yet been understood. The chemistry and micromorphology of soils from two of the best-known devastated sites in the park were investigated, representing the history of regional occupation across different phases (Lapas do Boquete and Malhador). To this end, deformed and undeformed samples were collected at different depths, provided for general characterization and preparation of thin sections for micromorphological study. Archaeoantrosols exhibit a polycyclic genesis, marked by successive climate changes, associated with distinct periods of human occupation. This occupation was episodic and cumulative over the millennia, with discontinuities related to greater or lesser human activity on the shelter and in the soils studied. Micromorphological analyses revealed the presence of a wide variety of small-scale allochthonous materials, such as bones, charcoal, shell fragments, and secondary products formed by the soil formation process. The deposition and preservation of unstable mineral phases throughout the Holocene reveal particular chemical conditions of the soils beneath shelters, formed in “sterile” and “non-sterile” layers beneath the rocky roof. The pedo-archaeological study becomes a key tool for the interpretation of these archaeological sites, reinforcing the need for greater interaction between pedology and archeology, and the Archaeoantrosols formed under protected conditions in the limestone shelter exhibit unique characteristics that allow them to be distinguished from other Brazilian archaeological soils, studied in different locations and different climates.