A strontium isoscape for the Conchucos region of highland Peru and its application to Andean archaeology

Strontium isotope ((87)Sr/(86)Sr) analysis of human skeletal remains is an important method in archaeology to examine past human mobility and landscape use. (87)Sr/(86)Sr signatures of a given location are largely determined by the underlying bedrock, and these geology specific isotope signatures are incorporated into skeletal tissue through food and water, often permitting the differentiation of local and non-local individuals in past human populations. This study presents the results of a systematic survey of modern flora and fauna (n = 100) from 14 locations to map the bioavailable (87)Sr/(86)Sr signatures of the Conchucos region, an area where the extent of geologic variability was previously unknown. We illustrate the necessity to examine the variation in (87)Sr/(86)Sr values of the different geological formations available to human land use to document the range of possible local (87)Sr/(86)Sr values. Within the Conchucos region we found significant variation in environmental (87)Sr/(86)Sr values (0.7078–0.7214). The resulting isoscape represents the largest regionally specific bioavailable (87)Sr/(86)Sr map (3,840 km(2)) to date for the Andes, and will serve as a baseline for future archaeological studies of human mobility in this part of the Peruvian highlands.