Mysterious Helium Leak Detected in Nevada

In Utah and eastern Nevada the Basin and Range is dominated by vertical faults which are not thought to penetrate to the mantle -- so there's less helium-3 getting though there, Kennedy surmised.

Further west, however, the north-south running faults shift more and more sideways -- north-south -- which creates shearing stresses in the crust. That shearing could penetrate to the mantle, creating conduits for hot fluids to move upwards even without a volcanic eruption.

A good example of Helium-3 getting up through a sideways-moving fault, says Kennedy, is the San Andreas Fault. Previous work had established excessive helium-3 there, he said.

The helium-3 in Nevada and along the San Andreas Fault could be also suggesting something important about how hot fluids from the mantle affect sideways-moving faults, and perhaps influence earthquakes.

"The role of deep fluid movement in changing stresses in the upper crust and triggering earthquakes remains unclear," reports geologist David Hilton of the Scripps Institution of Oceanography in La Jolla, Calif., "yet these two very different tectonic regimes share a common feature:" They both have excess helium-3 without any signs of volcanic activity.

The helium-3 map could also be pointing the way to good places to drill for clean, green, geothermal energy, Kennedy said. Right now there are very few clues, other than obvious geysers and hot springs, to guide geologists to geothermal resources. Helium-3 could be used as a sort of geothermal dowsing rod.

Related Links:

Larry O'Hanlon's blog: Earth Impacts

USGS: Basin and Range Province

Intro to Seismology from the USGS

Lawrence Berkeley National Laboratory