The Idaho National Laboratory is perhaps best known for its innovative research that is helping shape the clean energy economies of today and tomorrow, and for good reason. But while much of the lab’s work is focused on building a sustainable future, the INL is also doing its part to preserve the past.
INL researchers recently photographed several fossils using a powerful X-ray microscope. The 3D images will be used to create exhibits for Wyoming’s Fossil Butte National Monument and help experts better understand the origins of these and other relics.
The fossils, found in private quarries around Wyoming, were imaged using a technique known as X-ray microscopy. At INL, researchers typically use high-resolution X-ray microscopy to view specimens, such as samples of used nuclear fuel, at a level of detail not possible with conventional microscopes. The depth and granularity offered by this technique will help paleontologists learn a lot about these fossils – including an unknown object resembling an insect egg or a pea pod – and the conditions in which they formed.
“You can see the layers of limestone as well as sub-millimeter and thinner organic materials that have been compressed into waxy, pre-petroleum substances around the specimen,” said Arvid Aase, paleontologist and museum curator at Fossil Butte National Monument. “These incredibly detailed images will help us determine the organism’s taxonomy and reveal information about its fossilization process, such as how long it spent at the bottom of the lake covered in microbes before being buried by limestone. “
The fossilization process may have happened over a period of months, although the timing is still unknown, he added.
Buried in history
Limestone is a type of sedimentary rock that typically forms in shallow marine environments. As the remains of organisms with calcium carbonate shells, such as molluscs and snails, accumulate on the sea floor, they gradually form sedimentary layers. Through a process known as lithification, limestone deposits expand as calcium carbonate particles consolidate into solid rock formations. These formations often, but not always, contain fossils.
Scale can also form when water rich in calcium carbonate ions evaporates. Rainwater is slightly acidic and dissolves some of the limestone as it flows over or through it, breaking it down into calcium carbonate ions. As the standing water evaporates, the ions concentrate in the shallow lake or ocean. When the water reaches saturation, wind blowing the water releases dissolved carbon dioxide, causing the calcium carbonate ions to combine and create calcite molecules that settle to the bottom.
In the ancient Fossil Lake, where the unknown object was found, these carbonate molecules created a thin layer on a microbial mat, which recolonized the lake floor above the carbonate sediments several thousand times. Organisms that settled to the bottom were incorporated into the layers and fossilized. Over hundreds of years, the carbonate mud dried out and the molecules combined to become limestone.
“It appears that the unidentified fossil fell to the bottom of the lake during a storm, as limestone was present both above and below the fossil,” Aase said. The images will be sent to researchers at the University of Florida as well as Canada and France to help classify the cryptic fossil. “Based on the morphology, it may be an egg shell, although it could also be a seed structure,” he said.
Collaborate for science
The imaging was performed at INL’s Irradiated Materials Characterization Laboratory, a facility with sophisticated instrumentation primarily used to examine nuclear fuels and materials at the microstructural level after they have been irradiated in a reactor. The facility is one of 50 Designated Nuclear Science User Facilities (NSUF) across the country.
The Department of Energy’s NSUF program provides nuclear energy researchers with free access to these facilities and assistance at these facilities, with selection determined by a competitive process. Although this fossil imaging collaboration was not organized as part of the NSUF initiative, INL researchers hope to generate more interest among non-nuclear scientists in the use of these instruments.
“INL has the only ZEISS X-ray microscope in the Idaho/Montana/Wyoming area, and it can be used for a wide range of applications beyond post-irradiation examination,” said Nikolaus Cordes, an INL instrument scientist. “Providing local researchers with access to this microscope will help foster relationships, facilitate cutting-edge research in multiple scientific fields, and advance the INL’s cultural resource management mission.”
INL’s Cultural Resource Management team is responsible for integrating cultural resource considerations into the planning and implementation of projects and land use for laboratory projects and programs. The team includes archaeologists, historians and curators who help the INL carry out its mission while keeping in mind the fragile, natural and man-made artifacts, which are found in abundance on the property closely of 900 square miles from INL.
“I first came into contact with INL researchers about three years ago, and it was great to work with them,” Aase said. “The images we have obtained will go a long way in helping us learn more about the fossils themselves as well as the sediments in which they were found.”
Aase also plans to use the images to create rotating 3D exhibits for visitors to Fossil Butte National Monument.
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Provided by DOE/Idaho National Laboratory
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