geology – Lightsources.org

Ancient fluid in quartz provides key to finding new uranium deposits

2023/05/122023/05/19

Saskatchewan’s Athabasca Basin is home to some of the world’s largest and richest uranium deposits, but it can still be tricky to find them.

Researchers at the University of Regina are studying how the deposits formed more than 1.5 billion years ago to help figure out the best places to look.

“We’re trying to understand the geological factors that control the formation of these deposits so that we know what features we should be looking for to find more uranium resources,” said Dr. Guoxiang Chi, a geologist at the University of Regina.

Chi, his Ph.D. student, Morteza Rabiei, and colleagues used the Canadian Light Source (CLS) at the University of Saskatchewan to analyze samples of quartz from areas known to contain uranium and nearby barren regions, the quartz having formed at the same time as the Athabascan uranium ore. They sliced the quartz into thin sections and studied the tiny droplets of primordial fluid trapped inside. It was from this fluid, circulating through geological fault lines billions of years ago, that today’s uranium ore formed. “By getting information about this paleo-fluid and seeing how it is distributed we can infer where the original uranium came from and what factors control its deposition,” said Chi. Understanding the conditions under which uranium ore is likely to form can help mining companies know where to look.

The results, however, were more complex than expected, he said. Fluid from ore-bearing areas had high levels of uranium, as expected, but so did the fluid from areas with no uranium ore. On the one hand, that is good news as it means that the uranium-rich fluid is more pervasive than first thought, but it also complicates the search for new deposits.

“We were hoping to see a major difference, but found uranium-rich fluid in both places,” he said. “So, if we want to use it as a guide to locate ore, we’ll have to understand the other factors that control deposition.” Chi said those other factors likely involve reducing agents that allow precipitation of the oxidized uranium in the fluid. “Without a reducing agent, you can’t have ore.”

Read more on CLS website

Research on sand near Hiroshima shows fallout debris from A-Bomb blast

2019/05/132019/05/14

X-ray studies at Berkeley Lab provide evidence for source of exotic assortment of melt debris

Mario Wannier, a career geologist with expertise in studying tiny marine life, was methodically sorting through particles in samples of beach sand from Japan’s Motoujina Peninsula when he spotted something unexpected: a number of tiny, glassy spheres and other unusual objects.
Wannier, who is now retired, had been comparing biological debris in beach sands from different areas in an effort to gauge the health of local and regional marine ecosystems. The work involved examining each sand particle in a sample under a microscope, and with a fine brush, separating particles of interest from grains of sediment into a tray for further study.

Image: Researchers collected and studied beach sands from locations near Hiroshima including Japan’s Miyajima Island, home to this torii gate, which at high tide is surrounded by water. The torii and associated Itsukushima Shinto Shrine, near the city of Hiroshima, are popular tourist attractions. The sand samples contained a unique collection of particles, including several that were studied at Berkeley Lab and UC Berkeley.
Credit: Ajay Suresh/Wikimedia Commons

Research gives clues to CO2 trapping underground

2018/08/082018/08/09

CO2 is an environmentally important gas that plays a crucial role in climate change.

It is a compound that is also present in the depth of the Earth but very little information about it is available. What happens to CO2 in the Earth’s mantle? Could it be eventually hosted underground? A new publication in Nature Communications unveils some key findings.

Carbon dioxide is a widespread simple molecule in the Universe. In spite of its simplicity, it has a very complex phase diagram, forming both amorphous and crystalline phases above the pressure of 40 GPa. In the depths of the Earth, CO₂ does not appear as we know it in everyday life. Instead of being a gas consisting of molecules, it has a polymeric solid form that structurally resembles quartz (a main mineral of sand) due to the pressure it sustains, which is a million times bigger than that at the surface of the Earth.

Researchers have been long studying what happens to carbonates at high temperature and high pressure, the same conditions as deep inside the Earth. Until now, the majority of experiments had shown that CO₂ decomposes, with the formation of diamond and oxygen. These studies were all focused on CO₂ at the upper mantle, with a 70 GPa of pressure and 1800-2800 Kelvin of temperature.

Picture: Mohamed Mezouar, scientist in charge of ID27, on the beamline.
Credit: S. Candé.

Direct and Efficient Utilization of Solid-phase Iron by Diatoms

2017/07/312018/01/18

A research team indicates that diatoms, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level.

A research team from Columbia University indicates that diatoms, photosynthetic marine organisms responsible for as much as 20% of photosynthesis in the world’s oceans, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level. Although iron is often present in the ocean, usually there is insufficient iron for diatoms and other organisms to grow quickly unless this iron is dissolved and in a form that can be used readily. This research establishes that iron from mineral phases can be quite bioavailable, and that the diatoms can use most forms of iron, but appear to have a preference for a specific form of iron, ferrous iron, in the mineral phases. This research is applicable to a wide variety of questions in earth and ocean sciences, including basic biology of nutrient acquisition, the coupling of physical and geological processes such as glaciers to climate and geoengineering.

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Picture: Glacial striations seen near Upsala Glacier, Argentina, where scientists collected glacial samples. This physical scraping produces sediments and dust that can fertilize plankton when it is delivered to the ocean.
Photo by Michael Kaplan/Lamont-Doherty Earth Observatory

Speedy X-Ray Detector Arrives at NSLS-II

2017/05/052017/10/16

Advanced detector fuels discovery by allowing users to collect massive datasets in less time.

The National Synchrotron Light Source II (NSLS-II), a DOE Office of Science User Facility at the U.S. Department of Energy’s Brookhaven National Laboratory, is a truly international resource. Geoscientists from Australia and France recently trekked across the globe to aim NSLS-II’s tiny, intense beams of x-ray light at thin samples of nickel-rich mineral gathered from a mine in far-off Siberia. They scanned these slices of geological material to see what other chemical elements were associated with the nickel. The group also examined slices of minerals grown in a lab, and compared results from the two sample suites to learn how massive metal deposits form.

Their experiment was the first to use a newly installed x-ray detector, called Maia, mounted at NSLS-II’s Submicron Resolution X-Ray Spectroscopy (SRX) beamline. Scientists from around the world come to SRX to create high-definition images of mineral deposits, aerosols, algae—just about anything they need to examine with millionth-of-a-meter resolution. Maia, developed by a collaboration between NSLS-II, Brookhaven’s Instrumentation Division and Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), can scan centimeter-scale sample areas at micron scale resolution in just a few hours—a process that used to take weeks.

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