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When you think of magnets, you’re probably imagining a lackluster third-grade science experiment, or the sticky palm tree souvenir you picked up on your last beach vacation, which now serves to hold the overdue electric bill on the fridge.
Yet magnetism is one of the most defining properties of our planet, allowing us to explain and understand phenomena, from anomalies in the human body, to the reasons why Santa Claus ostensibly lives at the North Pole.
Giant and ancient magnets could also help us understand climate change.
New research published in the journal Proceedings of the National Academy of Sciences reveals how giant magnetic fossils dating back 34 to 56 million years could help scientists understand times of significant environmental change – past and present.
A little background – Scientists have studied both giant needle-shaped “magnetofossils” found on the continental shelf at Wilson Lake, New Jersey.
As the study indicates:
The New Jersey continental shelf has seen a rapid global influx of clay, iron oxide mineralization, dinoflagellate blooms, and benthic foraminiferous species turnover.
As a result, these fossils contain the remains of microscopic, magnetotactic bacteria and other microorganisms with iron components. In the case of these bacteria, magnetotactic means that they orient themselves along magnetic field lines.
As the study explains, the bacteria present in the magnetofossils formed magnetic chains, acting like a small-scale compass. This magnetic ability guided microorganisms to favorable nutrients in nearby oceans using the Earth’s magnetic field as a roadmap to food.
Ancient giant magnetofossils, formed 34 to 56 million years ago, took these magnetic properties to another level, forming unique shapes, including “giant balls, spindles and needles”, which were around 20 years old. times the size of conventional magnetic fossils, according to Research.
How they did it – Unlike previous studies, which crushed samples of magnetofossils into powder, these researchers examined the fossils without damaging them.
Scientists have developed a new, high-resolution technology for analyzing magnetofossils, known as First Order Inversion Curves (FORC).
According to the study, FORC can “measure the response of all magnetic particles, including giant magnetofossils, in a bulk sediment sample.”
They also used transmission electron microscopy to generate an image of the specimens using an electron beam. Finally, they used simulations to predict the magnetic behavior of giant needles in fossils.
Preservation of samples is important for future research, Courtney Wagner, lead author of the study and a PhD student at the University of Utah, said in a press release.
“The extraction process can be long and unsuccessful, electron microscopy can be expensive, and destruction of samples means they are no longer useful for most other experiments,” says Wagner.
What’s up – The giant needle-shaped magnetofossils – much like the needle on a compass – produce “distinct magnetic signatures” from those typically found in conventional magnetic fossils, the researchers found.
These distinct characteristics could ultimately reveal other giant magnetofossils, according to the research.
The structure of conventional magnetofossils is “optimized for magnetic navigation” because they generate the “maximum magnetic moment with the minimum of iron,” the study said.
Oddly enough, the structure of the giant magnetofossils is more variable than what the researchers expected. One theory they present is that these giant magnetofossils may have formed when there was an abundance of iron, making efficient magnetic movements less critical to the survival of organisms.
Why is this important – Giant needle magnetofossils are only associated with periods of ancient environmental upheaval.
In turn, researchers could use these fossils to better understand how ecological disturbances affect ancient marine life and the ocean ecosystem.
“It’s so much fun to be part of a discovery like this, something that can be used by other researchers studying magnetofossils and intervals of planetary change,” says Wagner.
“This work can be used by many other scientists, inside and outside our specialist community. It’s very exciting and rewarding, ”she adds.
There are no living creatures that form giant magnetofossils, which makes the study of these specimens extremely important.
Ultimately, they could act as a time capsule, revealing ancient changes in the geological record – and hidden glimpses of modern climate change and the world’s oceans.
According to the study:
By studying the presence of giant magnetofossils, we can better understand how sensitive marine ecosystems have responded to past climate change.
If the microorganisms in these fossils could use magnetic fields to respond to past climate changes and adapt, using the Earth’s magnetic field to find nutrients for survival, perhaps these lessons could help us respond and to adapt to the current climate crisis.
And after – “The organisms that produced these giant magnetofossils are absolutely mysterious, but it leaves exciting research avenues open for the future,” said Ioan Lascu, study co-author and researcher at the Smithsonian National Museum of Natural History, in a press release.
But scientists need to do more research to fully understand the makeup of the magnetic bacteria in these giant fossils.
“Collecting and storing these samples requires specialized personnel, equipment and planning, which is why we want to save as much material as possible for further studies,” says Wagner.
Abstract: Coastal marine sediments deposited during the Paleocene-Eocene thermal maximum at Lake Wilson, New Jersey, contain abundant conventional and giant magnetofossils. We find that the giant needle-shaped magnetofossils of Wilson Lake produce distinct magnetic signatures in low noise, high resolution first order inversion curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Lake Wilson sediments. These simulations highlight the characteristics of a single domain and the high magnetic coercivity associated with the extreme elongation of giant needle crystals. So far, giant magnetofossils have only been identified in sediments deposited during global hyperthermic events and can therefore serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a non-destructive method for identifying giant magnetofossil assemblages in bulk sediments, which will allow testing of their ecology and significance to environmental changes.
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