The U.S. Geological Survey is using a familiar exploration technology to search for copper deposits in remote locations of Alaska.
Starting in 2014, researchers with USGS began studying the remote eastern Alaskan Range where copper porphyry deposits are known to exist, using hyperspectral surveying. The technique employs aircraft equipped with instruments that emit light. When the light hits a material, some of the light is reflected back, allowing scientists to measure it with a spectrometer. The shape of the spectrum is like a fingerprint that reveals the chemical composition of the rocks.
“We wanted to push the application of the technology in jagged terrain that poses challenges for aiming and aligning sensors and other equipment,” Raymond Kokaly, a research geophysicist at the U.S. Geological Survey (USGS) Crustal Geophysics and Geochemistry Science Center in Denver, CO, and lead author on the study, told EOS, a site published by the American Geophysical Union that covers earth and space science news.
Screenshot capture of USGS Fact Sheet.
In Alaska the geophysicists were specifically searching for the mineral muscovite, which is known to be associated with copper porphyries.
“In collaboration with the Alaska Division of Geological and Geophysical Surveys, the University of Alaska Fairbanks, and the National Park Service, the USGS is collecting and analyzing hyperspectral data with the goals of enhancing geologic mapping and developing methods to identify and characterize mineral deposits elsewhere in Alaska,” reads a fact sheet of the program written by the team.
After two days of flying over the area, a total of 1,900 square kilometres, the team mapped locations where muscovite was present in various quantities. The locations were then compared to known copper deposits, looking for patterns in the wavelengths of light that had been reflected back to the instruments. They found the densest muscovite deposits correlated with the known porphyries.
Kokaly told EOS that if the technique proves reliable, they may use hyperspectral imaging to explore for other minerals including gold and silver.
5 Comments
Rod B
This is a waste of the tax-payer’s money!
I and many others were intimately involved in porphyry copper exploration of the entire eastern Alaska Range from Northway to Chitina in the early 1970s. Then President Carter and D-2 came along. Many private sector geologists worked hard to inform the government about the incredible mineral potential of the region. WE gave them maps, regional geochemical sample data, site specific descriptions of porphyry, skarn, and VMS mineral localities. We went to Washington DC and made presentations to various Senators about the damage it would do to the national economy if these lands were totally withdrawn. So, what did they do? – They withdrew the entire eastern Alaska Range from mineral entry. Nobody can go into the area without a hard to get permit. No roads, no airstrips, no buildings, no exploration!
In certain parts of the area one can find copper and silver nuggets laying on the surface of the ground. Four totally locked up porphyry systems exist in Klein Creek, Baultoff, Horsfeld, and Cottonwood Creek.Porphyry and skarn occur in Carl Creek, Sheep Creek, and on the east flanks of Wiki Peak. The famous porphyry systems of Orange Hill, Bond Creek, and Monte Cristo Creek still lie there without a way to develop what has been found. The richest copper deposit ever found lies dormant in the McCarthy and Nizina River districts. A Carlin-style gold deposit at Chisana…just sitting there.
The current crop of government geologists weren’t even born when RAA, Hawley, Kennecott, Rio Tinto, WGM and others were actively making discoveries in the area. Instead of having private industry employ tens of thousands of persons for the exploration and evaluation work, YOU – the tax payer – get to fund your good-for-little government to do so. Way to go America! This is the new norm!
Rick
What do you expect, Rod B? It’s the government! Sad, how very sad we have a government run by idiots. Greedy, incompetent idiots.
Prospector
Why look elsewhere when these deposits have already been located? This makes no freakin’ sense.
HeadwallPhotonics
@RodB
In order to verify new technologies that can potentially reduce time and costs for prospecting resources, it is critical to have ground truthing at a known site. This way, the new data from the faster technique can be checked against mapping work that has been done in the past. Once verified, there is the trust that the new technology can fly to another remote location and collect meaningful, accurate data without putting people’s lives at risk for costly ground missions.
HeadwallPhotonics
@Andrew Topf
What was the hyperspectral instrument used in this study?