Burning and boiling of modern deer bone: Effects on crystallinity and oxygen isotope composition of bioapatite phosphate

The extent of preservation of stable isotope compositions in biomaterials exposed to burial and weathering continues to be a topic of some debate. Changes in the isotopic composition of archaeological bones and teeth during recrystallization are often suspected, but difficult to prove. Here, we examined the effects of heating (burning, boiling) on the isotopic composition of phosphate oxygen (δ18Op) in bone bioapatite from two modern White-Tailed deer (Odocoileus virginianus). Our experiments simulated cooking and refuse disposal practices, which have affected many archaeological samples. Original values for δ18Op were preserved at < 300 °C. At higher temperatures, values were lowered by as much as 7‰ from primary compositions. Only small changes in crystallinity (measured using FTIR and XRD) were observed from 25 to 675 °C, despite large shifts in δ18Op above 300 °C. Original values for δ18Op were preserved only at FTIR CI ≤ 2.5–2.7. XRD CI values were not sensitive to changes in δ18Op below ∼ 625 °C.