Tag: quartz

Ancient fluid in quartz provides key to finding new uranium deposits

Ancient fluid in quartz provides key to finding new uranium deposits

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

Asteroid impact in slow motion

Asteroid impact in slow motion

High-pressure study solves 60-year-old mystery

For the first time, researchers have recorded live and in atomic detail what happens to the material in an asteroid impact. The team of Falko Langenhorst from the University of Jena and Hanns-Peter Liermann from DESY simulated an asteroid impact with the mineral quartz in the lab and pursued it in slow motion in a diamond anvil cell, while monitoring it with DESY’s X-ray source PETRA III. The observation reveals an intermediate state in quartz that solves a decades-old mystery about the formation of characteristic lamellae in quartz hit by an asteroid. Quartz is ubiquitous on the Earth’s surface, and is, for example, the major constituent of sand. The analysis helps to better understand traces of past impacts, and may also have significance for entirely different materials. The researchers present their findings in the journal Nature Communications.

Large asteroid impacts can melt significant amounts of material from Earth’s crust (artist’s impression). Credit: NASA, Don Davis

Asteroid impacts are catastrophic events that create huge craters and sometimes melt parts of Earth’s bedrock.“ Nevertheless, craters are often difficult to detect on Earth, because erosion, weathering and plate tectonics cause them to disappear over millions of years,” Langenhorst explains. Therefore, minerals that undergo characteristic changes due to the force of the impact often serve as evidence of an impact. For example, quartz sand (which chemically is silicon dioxide, SiO2) is gradually transformed into glass by such an impact, with the quartz grains then being crisscrossed by microscopic lamellae. This structure can only be explored in detail under an electron microscope. It can be seen in material from the relatively recent and prominent Barringer crater in Arizona, USA, for example.

Read more on the DESY website

Image: Large asteroid impacts can melt significant amounts of material from Earth’s crust (artist’s impression)

Credit: NASA, Don Davis