Paleoclimatic reconstruction using the correlation in δ¹⁸O of hackberry carbonate and environmental water, North America

Celtis sp. (commonly known as “hackberry”) fruits were collected from 101 North American sites located in 13 states and one Canadian province between the years of 1979–1994. The biomineralized carbonate endocarp of the hackberry, which is a common botanical fossil found throughout the Quaternary sediments of the Great Plains, was analyzed for its δ¹⁸O value and plotted against the δ¹⁸O value of site environmental water to demonstrate the potential of the hackberry as a paleoclimate indicator. This correlation was reinforced by intensive studies on extracted tissue-water δ¹⁸O value and hackberry endocarp carbonate δ¹⁸O value from three trees in Sterling, Colorado. The observed correlation in the large data set between hackberry endocarp carbonate δ¹⁸O value and environmental water is [endocarp δ¹⁸O=38.56+0.69×environmental water δ¹⁸O] (R=0.88; R²=0.78; p value