|Uranium-series Absolute Dating of Ancient Ice|
We seek to develop an efficient, low-blank method of using U-Th-Pa isotopes to produce precise absolute dates for ancient ice. Other methods of dating ice, including layer counting and ice flow modeling, rely on a continuous sequence of ice. Age constraints on older ice are not precise enough to test climate models, or to make meaningful comparisons to other climate records. U-series isotopes offer a potential method for dating ice of half a million years or older. We have been developing an efficient method for separating ice from dust, allowing us to measure the build-up of daughter products 234U, 230Th and 231Pa in the ice. We are applying this dating method to ice from an area of the McMurdo Dry Valleys in Antarctica, which contains what some believe to be the oldest ice on earth.