UTIG RESEARCH PROJECTS ARCHIVE

Project Summary:
This proposal requests funds to continue collaborative work between the Universities of Arizona, Minnesota, and Texas, and Bristol University on the timing of late Quaternary climate change and ¹⁴C calibration. The proposed research stems ulitmately from the development of thermal ionization mass spectrometric (TIMS) ²³⁰Th dating some time ago (Edwards et al., 1987a, b), but relies heavily on the more recent development of TIMS ²³¹Pa measurements (Pickett et al., 1994) and the application of these measurements to the dating of carbonates (Gray et al., 1991; Cheng et al., 1996; Holden et al., 1996; Edwards et al., 1997). TIMS ²³¹Pa dating provides us with a second high-resolution chronometer covering the late Quaternary. When used together, the ²³⁰Th and ²³¹Pa dating schemes are powerful because they allow a rigorous test of diagenetic alteration, and consequently, the accuracy of an age. Even if the two ages disagree, it may be possible to constrain the true age of the deposit (Cheng et al., 1997; in review). It is rare in geology that one can establish an important variable such as time with the sort of accuracy and precision afforded by this approach. One of the best examples in geochemistry is uranium-lead dating of zircons. Not coincidentally, combined ²³⁰Th-²³¹Pa dating shares many of the features of uranium-lead dating. By applying this combined approach to corals and speleothems, we aim to (1) extend the calibration of the ¹⁴C chronometer, (2) resolve some of the more controversial aspects of the late Quaternary sea level curve, and (3) establish a long-term high-resolution climate record for the mid-continent area of North America.

• Collaborative Research: The Temperature History of the Western Pacific Warm Pool Over the Last 30 Ka