Publication details
Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest
| Authors | |
|---|---|
| Year of publication | 2021 |
| Type | Article in Periodical |
| Magazine / Source | Quaternary Research |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1017/qua.2021.18 |
| Doi | http://dx.doi.org/10.1017/qua.2021.18 |
| Keywords | Terrestrial gastropods; Oxygen isotopes; Paleoclimate; Paleowetland deposits |
| Description | Recent studies have shown the oxygen isotopic composition (delta O-18) of modern terrestrial gastropod shells is determined largely by the delta O-18 of precipitation. This implies that fossil shells could be used to reconstruct the delta O-18 of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this study, we measured the delta O-18 values of 456 individual gastropod shells collected from paleowetland deposits in the San Pedro Valley, Arizona that range in age from ca. 29.1 to 9.8 ka. Isotopic differences of up to 2 parts per thousand were identified among the four taxa analyzed (Succineidae, Pupilla hebes, Gastrocopta tappaniana, and Vallonia gracilicosta), with Succineidae shells yielding the highest values and V. gracilicosta shells exhibiting the lowest values. We used these data to construct a composite isotopic record that incorporates these taxonomic offsets, and found shell delta O-18 values increased by similar to 4 parts per thousand between the last glacial maximum and early Holocene, which is similar to the magnitude, direction, and rate of isotopic change recorded by speleothems in the region. These results suggest the terrestrial gastropods analyzed here may be used as a proxy for past climate in a manner that is complementary to speleothems, but potentially with much greater spatial coverage. |