Paleoclimatic Reconstruction Using the Correlation in δ¹⁸O of Hackberry Carbonate and Environmental Water, North America

Abstract

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<0.0001). The relation of the hackberry carbonate to temperature in the Great Plains was the following: (average daily-maximum growing season temperature [°C])=6.33+0.67 (δ18O of endocarp carbonate) (R=0.73; R2=0.54; p value=0.0133). The δ18O value of early Holocene fossil hackberry carbonate in the Pintwater Cave, southern Nevada, suggested precipitation δ18O values more positive than today (∼−4‰ early Holocene vs ∼−9 to −10‰ today). This shift, combined with paleobotanical data, suggests an influx of summer monsoonal moisture to this region in the early Holocene. Alternatively, the more positive δ18O values could be viewed as suggestive of warmer temperatures, although the direct use of Great Plains hackberry/temperature relationships to the Great Basin is of debatable value.

Fossil fruit identification by SEM investigations, a tool for palaeoenvironmental reconstruction of Dmanisi site, Georgia

“…These fruits do not even need to have been in contact with fire to be preserved as the carbonated composition and sometimes silica bodies contained in their fruit stones contribute to their mineralisation (Retallack, 1990;Jahren et al, 1998Jahren et al, , 2001Pustovoytov and Riehl, 2006). Due to this phenomenon, it is possible to identify different genera in a precise manner and thus to reconstruct environmental conditions even in Early Pleistocene times.…”

Radiocarbon Dating, Mineralogy, and Isotopic Composition of Hackberry Endocarps from the Neolithic Site of Aşikli Höyük, Central Turkey

“…This suggests that most fossil plants harvested for their hackberries at Aşıklı are drawing on evaporated soil water, rather than the local (perched and regional) water table sampled in our study. We compare these analyses to that of endocarps predicted to form from a range of local meteoric waters (horizontal lines) using the endocarp-water relationship for North American hackberries described in Jahren et al (2001) (see text). An interesting exception is represented by four endocarps, samples AH-64a-d in Table 3.…”

Oxygen isotopic composition of fruit carbonate in Lithospermeae and its potential for paleoclimate research in the Mediterranean

“…Boraginaceae) and its potential for paleoclimate research. Previously, biogenic carbonate in fruits of flowering plants has been studied isotopically in the genus Celtis (Wang et al, 1997;Jahren et al, 1998Jahren et al, , 2001. These works addressed the processes of biomineralization in fruit tissues (Jahren et al, 1998) as well as the radiocarbon content (Wang et al, 1997) and oxygen isotopic composition (Jahren et al 2001) of fruit carbonate.…”

“…Previously, biogenic carbonate in fruits of flowering plants has been studied isotopically in the genus Celtis (Wang et al, 1997;Jahren et al, 1998Jahren et al, , 2001. These works addressed the processes of biomineralization in fruit tissues (Jahren et al, 1998) as well as the radiocarbon content (Wang et al, 1997) and oxygen isotopic composition (Jahren et al 2001) of fruit carbonate. It has been demonstrated that the δ 18 O values of biogenic carbonate in Celtis fruits are correlated to δ 18 O of local meteoric water and, for the studied ecological range, also to mean annual temperatures (Jahren et al, 2001).…”