The rocks of Vedauwoo east of Laramie are excellent examples of A-type granites.
Nearly 100 scientific publications have resulted from a six-year international geological
research project co-led by University of Wyoming Professor Carol Frost.
From 2005-2010, Frost, a professor in the Department of Geology and Geophysics, helped
lead an international team of scientists from 42 nations on six continents that researched
the origins, age, distribution, physical properties and other aspects of A-type granites.
In August Frost and co-leaders Tapani Ramo (Finland) and Roberto DallAgnol (Brazil)
held the final technical meeting and field trip for the United Nations Educational,
Scientific and Cultural Organization's International Geoscience Programme on "A-type
Granites and Related Rocks through Time."
"A-type granites are iron-rich granites found within tectonic plates, as opposed to
most other granites that are intruded along plate margins, such as the Cascades and
California's Sierra Nevada," says Frost. Field research studies were conducted in
different crustal realms and tectonic settings in North America, South America, Africa
and Europe.
Wyoming hosts excellent examples of A-type granites, Frost says. Among them are the
1.4 billion year-old Sherman granite that is exposed at Vedauwoo east of Laramie.
She says A-type magma also is present in Yellowstone, where some of it erupted and
deposited huge volumes of volcanic ash, most recently 600,000 years ago.
"The remaining magma that is still underground beneath Yellowstone will eventually
cool and crystallize as A-type granite," Frost says. "For that reason I call Vedauwoo
'Yellowstone Underground' because we can see at Vedauwoo what is forming below Yellowstone's
geysers and thermal features."
In addition to the field research, the project included seven technical meetings in
the United States, Brazil, South Africa, Canada, Norway, Turkey and Finland.
The UNESCO project was very rewarding, Frost says, because it brought together geologists
who'd studied iron-rich granites from all parts of the globe. The scientists had many
arguments about how these rocks formed, and divergent hypotheses resulted.
"Through our annual meetings and field trips to some of these locations we came to
realize that much of the controversy stemmed from the fact that we were comparing
apples and oranges, so to speak," she says. "By the end of the project we all realized
that it is possible to make compositionally similar, but not identical granites by
melting different kinds of rocks in the crust and mantle."
Frost says the participants developed many collaborations and points of contact among
developed and developing countries and among scientists with different but complementary
expertise.
"It was a wonderful, broadening, international experience for all," Frost says.
More information and updates on publications (and other pertinent issues related to
the project) can be retrieved from the project Web site at www.IGCP-510.org.
