"You could boil it down to processes as broad as 'why are there mountains' to 'should we drill for oil here,'" Copeland said. "Both of these questions involve asking how hot was this rock and when did it cool off."
There are standard methods for making that critical determination, specifically the decay of uranium to helium or how fast helium moves through a rock. Copeland found that process to work well if the rock was plentiful in uranium, but how could you coax the tale from rocks whose stash of uranium was not as plentiful, like those needed to look for oil. Copeland tried a new application of an old technique using a garden variety mineral—calcite.
"What I have learned is that helium is retained in this very common mineral, calcite, at temperatures that are useful to geologist. Therefore we can date them learn their age and apply them to geologic problems," he said.
The technique is not without its detractors. But Copeland's promising calcite-technique, supported by the National Science Foundation and area oil companies, opens up a new class of rocks like limestones and shales to add to the story of the history of the Earth.
The department of earth and atmospheric sciences is part of what's happening at the University of Houston. I'm Marisa Ramirez.
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