CRONUS-Earth Project Seeks To Improve Accuracy of Geo-Dating, July 14, 2005

by George Zamora

SOCORRO, N.M., July 14, 2005 – A New Mexico Tech geoscientist who developed an accurate method of dating geological landforms by measuring localized accumulations of radioactive elements on the Earth’s surface is now spearheading a national effort to improve the accuracy and reliability of the widespread applications of these types of geochronology methods.

Fred M. Phillips, professor of hydrology at New Mexico Tech, is the principal investigator of the recently started CRONUS-Earth Project, a multi-year, multi-disciplinary research project funded by the National Science Foundation (NSF). The acronym CRONUS stands for Cosmic-Ray Produced Nuclide Systematics.

In the early 1990s, Phillips pioneered using a geochronology method that is based on measuring the natural occurrence of chlorine-36, a radioisotope which normally forms when highly energetic cosmic-ray particles from outer space strike argon atoms present in the Earth’s atmosphere. The cosmogenic-nuclide technique developed by Phillips has since enabled geoscientists worldwide to accurately date groundwater, landforms, rocks, minerals, and other geologic materials ranging from thousands of years old to slightly more than one million years old.

Other similar surface exposure dating techniques currently employed by scientists use measurements of the ratios of other radioisotopes, such as helium-3, berylium-10, carbon-14, neon-21, and aluminum-26.

The CRONUS-Earth Project is tasked with rigorously and systematically identifying and investigating sources of uncertainty in cosmogenic-nuclide production so as to improve the accuracy and reliability of geochronology techniques and other scientific applications that rely on analyses of cosmogenic surface exposure.

Furthermore, the five-year research project is intended to establish benchmark parameters and models that will consistently provide Earth scientists working in research laboratories throughout the world with precise estimations of exposure history on geologic timescales, which are derived from measurements of cosmogenic nuclides.

“As scientists who use geochronology techniques in the course of their research, we need to know exactly how cosmic rays are distributed throughout space and time,” says Phillips, “all the while taking into account differences in measurement variables such as longitude, latitude, and elevation, as well as changes that occur over geological timescales, such as periodic shifts in the Earth’s magnetic field.”

Because of its large scale and scope, the CRONUS-Earth Project will be managed using a layered, coordinated “consortium approach,” Phillips says, involving multiple institutions and investigators, annual meetings to collectively monitor progress, compile data, and exchange information, and integration of the final results through a project office charged with distributing and disseminating information and results.

Practically all the various sub-disciplines of Earth science dealing with the surface of the planet will stand to benefit from the improved geochronology methods that will result from the CRONUS-Earth Project, Phillips says, including paleoclimatology, geomorphology, tectonics, volcanology, geologic hazards, meteorology, paleomagnetism, and hydrology.

In addition to New Mexico Tech, 12 other research institutions are directly involved with the CRONUS-Earth Project, including the University of Arizona, the University of Washington, Scripps Institution of Oceanography, Woods Hole Oceanographic Institute, Lamont-Doherty Earth Observatory of Columbia University, Lawrence Livermore National Laboratory, and the PRIME Lab at Purdue University.

[ NSF website]