Using the 230Th/U and 234U/238U methods, this lab is capable of dating samples ranging in age from about a million years old to less than 100 years. On suitable materials, the 230Th/U method is sufficiently precise and reliable that it is used as the ultimate calibration of the radiocarbon dating method for samples older than about 10,000 years.
Using the U-Pb method, this laboratory also provides precise dates for rocks and minerals ranging in age from billions of years to about a million years. Because of the extreme resistance of such minerals as zircon to age resetting, the U-Pb system has proven more reliable than other dating methods for rocks that have been strongly reheated, sheared, or exposed to hydrothermal fluids.
The Uranium-Daughter Laboratory features a Micromass Sector54 thermal-ionization mass spectrometer, equipped with a WARP filter for very high abundance sensitivity, eight Faraday collectors (for ultra-high precision analyses of large samples), and an ion-counting collector (for analyses of extremely small samples). The computer-positioned, motorized collectors and highly flexible software permit unattended analyses of up to 20 samples of any mix of elements, so that several research groups can be accommodated by the instrument. Samples for the thermal-ionization mass spectrometer are prepared in a clean lab, equipped with a highly-filtered, positive-pressure air supply, and four ultraclean HEPA-filtered laminar-flow workstations for the most contamination-sensitive procedures. Routine contamination levels in the lab for zircon analyses have been reduced to less than a trillionth of a gram of lead, permitting U-Pb dating of single crystals of zircon finer than a grain of sand and of almost any age.