Snails, stable iostopes, and southwestern desert paleoclimates
- Univ. and Community College System of Nevada, Reno, NV (United States)
Modern and fossil molluscs (snails) occur in many localities in and semi-arid regions throughout the desert southwest. Live terrestrial snails are found under rocks and in forest litter and aquatic taxa inhabit springs, seeps, and/or wetlands. Molluscs uptake local water during their growing season (spring and summer) and incorporate its delta 180 signature into their shells. Preliminary 180 analysis of modem shells from the southern Great Basin indicates that the shells probably reflect meteoric water 180 values during the growing season. This provides a way to estimate the delta 180 value of precipitation and, thereby, the source of the moisture-bearing air masses. Significant 180 variability in shells analyzed include geographic location, elevation, taxonomy, and habitat (terrestrial, spring, or wetland). We found a rough inverse correlation with elevation in modem shells from the Spring Range in southern Nevada. The delta 180 values of modem and fossil shells are also very different; modem values in this location are much higher than those from nearby late Pleistocene-age molluscs suggesting that the Pleistocene summers were variously colder and wetter than today or less evaporative (more humid). Assuming shell material directly reflects the 180 of the growing-season environment, comparison of modem and fossil shell delta 180 values can potentially identify changes in air-mass moisture sources and can help to define seasonal precipitation change through time. Comprehension and quantification of community and isotopic variability in modem gastropods is required to create probabilistic valid transfer functions with fossil materials. Valid inferences about past environmental conditions can then be established with known confidence limits.
- Research Organization:
- Rust Geotech, Inc., Grand Junction, CO (United States)
- OSTI ID:
- 198212
- Report Number(s):
- CONF-9409325-; ON: DE96003275; TRN: 96:001174-0003
- Resource Relation:
- Conference: Workshop on climate change in the four corners and adjacent regions: implications for environmental restoration and land-use planning, Grand Junction, CO (United States), 12-14 Sep 1994; Other Information: PBD: Sep 1995; Related Information: Is Part Of Climate change in the four corners and adjacent regions: Implications for environmental restoration and land-use planning; Waugh, W.J. [ed.]; PB: 199 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Climatic effects of irrigation over the Huang-Huai-Hai Plain in China simulated by the weather research and forecasting model: Simulated Irrigation Effects in China
Sensitivity studies on the impacts of Tibetan Plateau snowpack pollution on the Asian hydrological cycle and monsoon climate