Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geologists map Cartwright country

16.06.2004


’Big Bonanza’ and the Comstock Lode



Remember the burning Ponderosa map at the beginning of the long-running TV show "Bonanza"? It’s up in flames before you can read all the place names.
Now a geologist at Washington University in St. Louis has replaced that map with one of the famous ore site known as the Comstock Lode, a part of which is the "Big Bonanza."

While it’s doubtful that Hoss, Adam and Little Joe – not to mention the sages, Pa and Hop Sing – could make heads nor tails of it, the map is a valuable contribution to geology because it gives an interpretation of the flow of hot waters interacting with rock some 14 million years ago that created the ore district. Between 1859 and 1882, the Comstock Lode produced gold and silver in such quantities that the bullion would be worth several billion dollars in today’s markets.



Robert Criss, Ph.D., professor of earth and planetary sciences in Arts & Sciences, and his former graduate student Michael J. Singleton, Ph.D., now at Lawrence Berkeley National Laboratory, analyzed 327 rock samples collected from a portion of the Comstock Lode as well as historical samples and ones from the Smithsonian Institute and "visualized" a kind of symmetrical flow. They were able to determine the flow thanks to a mathematical technique called kriging that allows computer contouring of oxygen isotope data gleaned from the rock samples.

When water and rock interact in ore deposition they exchange isotopes. Isotopes are different variations of the same element. There are three oxygen isotopes, oxygen-16, -17 and -18. All three behave chemically as oxygen, differing only in their mass. Most is oxygen-16, but about one oxygen atom in 500 is oxygen-18, and only one in about 2,500 is oxygen-17. Rocks are about 50 percent oxygen by weight, water 90 percent. The exchange of isotopes – the researchers measured O-16 and O-18– creates "patterns of disturbance" in the rock, which the researchers can map by combining a lot of field work with lab analysis and computing.

"We can map and interpret these patterns long after the disturbance happened -– 12 to 14 million years ago" said Criss. " The rocks preserve a record of what happened."

Criss said the hydrothermal flow geometry that created the ore district was a longitudinal roll pattern superimposed on a unicellular flow system. Think of the longitudinal rolls as two parallel tubes and the unicellular system as a flat roll. The map is the first evidence showing the longitudinal roll pattern occurring in nature. The system had been predicted by theory but never seen before in an ore district.

"We’ve shown that these modes of convection can occur on Earth under the right circumstances," Criss said. "It’s the first description of such symmetry in an ore district. The ore body positions have an obvious relationship to these rolls. "

The research was published in the April issue of the Journal of Geophysical Research. It was supported by funding from the National Science Foundation.

The finding is important for geologists to understand the creation of ore deposits. These events occur underground and must be analyzed remotely. And it could have economic implications.

"It’s possible, under perfect conditions, to understand currents of fluid that make ore bodies," Criss said. "If this could become part of a predictive tool to locate currents that form ore bodies, that would be a valuable outcome because we don’t have very good theories on how ore bodies are formed. It’s a very peculiar process."

Tony Fitzpatrick | EurekAlert!
Further information:
http://www.wustl.edu/

More articles from Earth Sciences:

nachricht Geophysicists and atmospheric scientists partner to track typhoons' seismic footprints
16.02.2018 | Princeton University

nachricht NASA finds strongest storms in weakening Tropical Cyclone Sanba
15.02.2018 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>