Studying environmental change through carbon isotopes in ancient Maya wetlands

Keywords: Soil, Geoarchaeology, Human - environment interactions
Session Type: Virtual Paper Abstract
Day: Tuesday
Session Start / End Time: 3/1/2022 02:00 PM (Eastern Time (US & Canada)) - 3/1/2022 03:20 PM (Eastern Time (US & Canada))
Room: Virtual 16

Abstract

Fossil lines of evidence in neotropical soils has presented a dilemma for scientist interested in vegetation change during ancient and modern time frames. This is largely due to limitations on pollen preservation in tropical soils and equivocal evidence from complimentary lines of data such as phytoliths. As a result, scientist have measured stable carbon isotope ratios of soil organic matter to study broad vegetation changes characterized by the normalized difference between C4 and C3 species. We now have studies that have examined profile shifts in many types of soil environments from ancient to modern agricultural terraces, floodplains, and wetland fields. Here we present synthesized data from three wetland field complexes in the floodplains of the Rio Bravo near the ancient Maya sites of Birds of Paradise, Wari Camp and Chawak But’o’Ob. That synthesis integrates evidence from stable and radiogenic carbon isotopes along with other soil proxies including elemental chemistry and fossil data to better understand ancient land use. Stable carbon isotope sequences of these ancient wetland field sites reveal shifts to more C4 dominated carbon organic matter during Maya occupation both in pre-raised field floodplains as well as in the raised fields. These sites are likely to indicate locations where intensive Maize agriculture persisted long enough to shift the stable carbon isotope signature of the soil organic matter. AMS dating of charcoal through these sequences also helps constrain the timing of these changes in vegetation along the floodplain.