Lab Work: Extracting U and Pb from Zircon Crystals

One of the primary goals of this project is to date the various small volume eruptions in the Black Rock Desert in conjunction with chemical analyses of the lavas to better understand the processes that control magma evolution. To that end, we are using U/Pb dating and trace element geochemistry of zircon crystals to determine both the timing of crystallization and to estimate the temperature of the magma during crystallization. This type of dating is one of the oldest, most well-refined and allows us to date the rocks within 0.1-1% accuracy. This dating technique works by measuring the decay of U to Pb and using its half-life to determine how long the decay process has been going on.

Once the zircon crystals are separated from the volcanic rock, we extract the U and Pb through a technique called column chemistry, shown in the photos below. We dissolve the zircon crystals in Teflon microcapsules, and then load onto micro-columns that are prepared with resin and use a recipe of various acids to slowly extract the U and Pb.

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