Mass-Spectrometric 230 Th- 234 U- 238 U Dating of the Devils Hole Calcite Vein

Abstract

The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric U-series ages for samples from core DH-11 yielded ²³⁰Th ages with precisions ranging from less than 1,000 years (2σ) for samples younger than ∼140 ka (thousands of years ago) to less than 50,000 years for the oldest samples (∼566 ka). The ²³⁴U/²³⁸U ages could be determined to a precision of ∼20,000 years for all ages. Calcite accumulated continuously from 566 ka until ∼60 ka at an average rate of 0.7 millimeter per 10³ years. The precise agreement between replicte analyses and the concordance of the ²³⁰Th/²³⁸U ²³⁴U/²³⁸U ages for the oldest samples indicate that the DH-11 samples were closed systems and validate the dating technique in general.