Cosmogenic Nuclide Laboratories

We have two spacious wet-chemical labs for cosmogenic nuclide sample preparation. One is devoted to purification of quartz. The other is devoted to mineral dissolution and extraction of the cosmogenic nuclides Al-26 and Be-10. We use these nuclides to measure rates or weathering, erosion, and sedimentation in mountainous settings.

Principal Investigator:

Cliff Riebe

We are always on the lookout for conscientious undergrads to join our team. Please contact Cliff about opportunities!

Research:

Cosmogenic nuclides are produced in geologic materials in the uppermost few meters of Earth’s crust. So they can show us how long minerals have been close to the surface. We use this information to measure rates of erosion, weathering and sedimentation in landscapes. These measurements are important for solving a range of discipline-spanning problems in geomorphology, low-temperature geochemistry, soil science and geobiology.

We have an array of equipment and facilities for cosmogenic nuclide sample preparation at the University of Wyoming. The first step in the process is to isolate quartz from everything else in our samples of crushed rock, sediment and soils. Quartz is a target mineral for production of Be-10, which at the moment is the most widely used nuclide both in our studies and in the literature as well.

Because Be-10 is produced slowly (at just 22 atoms per gram per year in the Laramie area) we need large amounts of quartz so that there are enough atoms to measure. To concentrate the quartz, we use techniques that exploit differences in chemical and physical properties among the minerals in our samples. Most important are magnetic separation, froth floatation, heavy liquid separation, preferential dissolution, and finally etching of mineral surfaces to purify what’s left.

Once we have enough pure quartz, we dissolve it and extract beryllium using preparative ion chromatography. The Be is then converted to oxide-form and packed for isotopic analysis by Accelerator Mass Spectrometry (AMS) at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab).

Why go to all this trouble? Before cosmogenic nuclides came into widespread use in the late 1980s, there was no widely applicable way to quantify rates of erosion and weathering over 100 to 1,000 year timescales in landscapes. Now there's a way, and though the chemistry involves a lot of effort, the payoff is a valuable measurement that helps us understand how landscapes have been changing over time. Cosmogenic nuclides are a big deal. They are near the center of the ongoing quantitative revolution in surface processes research.

Equipment:

• dedicated furnaces, oven and centrifuge
• induced-roll magnetic separator
• bottle-rolling system
• heavy-liquid separation station
• high-intensity ultrasonic generator & tank
• acid-neutralization system
• high-purity (18.2 MΩ cm) water supply
• acid-resistant fume hood and venting system
• apparatus for preparative ion chromatography

User Information:

This lab is open to outside users for collaborative purposes at the discretion of the PI. The cost of consumables for Be-10 sample preparation average around $250 per sample. However this can vary substantially, depending especially on the amount of quartz in the sample. AMS facility charges are extra. Currently it costs $230 per nuclide for subsidized NSF projects. It costs more for non-NSF research and private (for profit) analyses. See PRIME Lab pricing for details. Please contact Cliff if you have questions about using the Cosmogenic Nuclide Laboratories.