HR: 1340h
AN: U33A-0005    [Abstracts]
TI: Comparison of Chlorine-36 Production Rates Using the Radiocarbon-Age-Constrained Lake Bonneville Shoreline, UT
AU: * McGee, S L
EM: shasta@nmt.edu
AF: New Mexico Institute of Mining and Technology, New Mexico Tech Earth and Environmental Science 801 Leroy Place, Socorro, NM 87801 United States
AU: Phillips, F M
EM: phillips@nmt.edu
AF: New Mexico Institute of Mining and Technology, New Mexico Tech Earth and Environmental Science 801 Leroy Place, Socorro, NM 87801 United States
AB: As part of the CRONUS-Earth project, geological calibrations for in-situ production of cosmogenic nuclides, including chlorine-36, are being conducted as part of a larger project to improve the accuracy of techniques employing cosmogenic nuclides. For these calibration purposes, samples were taken from two age-constrained locations representing the Lake Bonneville shoreline: Tabernacle Hill and Promontory Point. Lake Bonneville is an ancient glacial lake that occupied a large area surrounding what is currently the Great Salt Lake in Utah during the last glacial period. This lake reached its highest level, the Bonneville stage, and remained there for only a short period of time (18.9-17.2 cal ka) before a catastrophic flood lowered the lake level to the Provo stage. This is a good calibration site because of the numerous radiocarbon dates available and the short time-frame of the events. Tabernacle Hill is a basalt flow which erupted shortly after the Lake Bonneville flood, during the Provo stage and provides a boundary on the Bonneville flood age. Surface samples exhibiting flow characteristics indicative of the original surface were collected using a rock saw and chisels. At Promontory Point, the original surfaces that were sampled are wave-polished outcrops on the wave-cut bench corresponding to the Lake Bonneville shoreline. The objective of this study is to use these age-constrained samples to compare the previously-published in-situ chlorine-36 production rates. The age of the two calibration surfaces will be calculated using the production rates from the literature. These ages based on existing calibrations will be compared to the independent age determined by radiocarbon dating. This comparison will be used to evaluate the accuracy of the previous production rates at these sites.
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
SC: Union [U]
MN: Fall Meeting 2005