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A chunk of the Grand Canyon found in Australia could offer answers about how Earth was formed
According to a paper published in Geology by geologists at Monash University, a strip of the north-west coast of Tasmania is likely to be the Grand Canyon's long-lost cousin.
Research conducted by the geologists suggests the "unusual" rocks have a similar geochemical fingerprint to rocks from the Grand Canyon in the USA.
They're part of a very famous bit of land, Rocky Cape National Park, where cave middens reveal evidence of Aboriginal occupation from at least 8000 years ago. It's been officially recognized as "Pinmatik" ("peen mah teek") since 1991.
But hundreds of millions of years ago, it was part of a megacontinent known as Rodinia, and joined to what is now known as the west coast of the USA, 13,000km away.
In particular, it's got bits of the Grand Canyon in it, and that makes it very, very interesting for Earth science researchers.
Rodinia was formed when an even older supercontinent known as Columbia broke apart, but you won't find any Rodinian fossils at Rocky Cape, because Rodinia existed one billion years ago, well before terrestrial life had formed.
It began breaking up around 700 million years ago.
Jack Mulder, a research fellow at Monash University in Melbourne, thought the rocks looked similar to those in the Grand Canyon, and decided to test his theory.
It turned out that rocks from both regions shared similar stratigraphy, depositional age, and they contain matching hafnium isotopes readings.
Mulder was able to trace where the ancient sand and mud came from by analyzing the geochemical fingerprint of tiny grains of the mineral zircon, which makes up a small proportion of the sedimentary rocks.
"When we compared the Tasmanian rocks to similar-aged rocks nearby in Australia, we found that not only did they look very different, but they also had distinct zircon fingerprints. Instead, the enigmatic Tasmanian rocks look strikingly similar to the one billion-year-old sedimentary rocks found near the bottom of Grand Canyon in Arizona," he said.
"In addition to forming at the same time and in similar geological environment, the ancient sedimentary rocks in Tasmania and Grand Canyon share the same zircon fingerprint. Together, this evidence supports the interpretation that these now widely separated rock units once formed part of the same sedimentary basin."
That dates "Pinmatik" back as much as 1.1 billion years to the late Mesoproterozoic era.
One professor, Alan Collins, at the University of Adelaide, Australia, told New Scientist the paper shows Tasmania "holds the key" to understanding how the planet was put together.
It could help future geologists build full plate models of ancient Earth, he said. [Reply]
European scientists say they have made a major breakthrough in their quest to develop practical nuclear fusion - the energy process that powers the stars.
The UK-based JET laboratory has smashed its own world record for the amount of energy it can extract by squeezing together two forms of hydrogen.
If nuclear fusion can be successfully recreated on Earth it holds out the potential of virtually unlimited supplies of low-carbon, low-radiation energy.
The experiments produced 59 megajoules of energy over five seconds (11 megawatts of power).
This is more than double what was achieved in similar tests back in 1997.
It's not a massive energy output - only enough to boil about 60 kettles' worth of water. But the significance is that it validates design choices that have been made for an even bigger fusion reactor now being constructed in France.
"The JET experiments put us a step closer to fusion power," said Dr Joe Milnes, the head of operations at the reactor lab. "We've demonstrated that we can create a mini star inside of our machine and hold it there for five seconds and get high performance, which really takes us into a new realm."
For the first time, researchers have spotted short-term, regional fluctuations in atmospheric carbon dioxide (CO2) across the globe due to emissions from human activities.
Using a combination of NASA satellites and atmospheric modeling, the scientists performed a first-of-its-kind detection of human CO2 emissions changes. The new study uses data from NASA’s Orbiting Carbon Observatory-2 (OCO-2) to measure drops in CO2 emissions during the COVID-19 pandemic from space. With daily and monthly data products now available to the public, this opens new possibilities for tracking the collective effects of human activities on CO2 concentrations in near real-time.
Previous studies investigated the effects of lockdowns early in the pandemic and found that global CO2 levels dropped slightly in 2020. However, by combining OCO-2’s high-resolution data with modeling and data analysis tools from NASA’s Goddard Earth Observing System (GEOS), the team was able to narrow down which monthly changes were due to human activity and which were due to natural causes at a regional scale. This confirms previous estimates based on economic and human activity data.
The team’s measurements showed that in the Northern Hemisphere, human-generated growth in CO2 concentrations dropped from February through May 2020 and rebounded during the summer, consistent with a global emissions decrease of 3% to 13% for the year.
The results represent a leap forward for researchers studying regional effects of climate change and tracking results of mitigation strategies, the team said. The method allows detection of changes in atmospheric CO2 just a month or two after they happen, providing fast, actionable information about how human and natural emissions are evolving.
Discerning subtle changes in Earth’s atmosphere
Carbon dioxide (CO2) is a greenhouse gas present in the atmosphere and its concentration changes due to natural processes like respiration from plants, exchange with the world’s oceans, and human activities like fossil fuel combustion and deforestation. Since the Industrial Revolution, the concentration of CO2 in the atmosphere has increased nearly 49%, passing 400 parts per million for the first time in human history in 2013.
When governments asked citizens to stay home early in the COVID-19 pandemic, fewer cars on the road meant steep drops in the amount of greenhouse gases and pollutants released into the atmosphere. But with CO2, a “steep drop” needs to be put in context, said Lesley Ott, a research meteorologist at NASA’s Global Modeling and Assimilation Office at Goddard Space Flight Center in Greenbelt, Maryland. This gas can last in the atmosphere for up to a century after it is released, which is why short-term changes could get lost in the overall global carbon cycle – a sequence of absorption and release that involves natural processes as well as human ones. The lockdowns of early 2020 are one small part of the total CO2 picture for the year.
“Early in 2020, we saw fires in Australia that released CO2, we saw more uptake from plants over India, and we saw all these different influences mixed up,” Ott said. “The challenge is to try to disentangle that and understand what all the different components were.”
Up until recently, measuring these kinds of changes wasn’t possible with satellite technology. NASA’s OCO-2 satellite has high-precision spectrometers designed to pick up even smaller fluctuations in CO2, and combined with the comprehensive GEOS Earth system model, were a perfect fit to spot the pandemic-related changes.
“OCO-2 wasn’t designed for monitoring emissions, but it is designed to see even smaller signals than what we saw with COVID,” said lead author Brad Weir, a research scientist at Goddard and Morgan State University. Weir explained that one of the OCO-2 mission research goals was to track how human emissions shifted in response to climate policies, which are expected to produce small, gradual changes in CO2. “We hoped that this measurement system would be able to detect a huge disruption like COVID.”
The team compared the measured changes in atmospheric CO2 with independent estimates of emissions changes due to lockdowns. In addition to confirming those other estimates, the agreement between emissions models and atmospheric CO2 measurements provides strong evidence that the reductions were due to human activities.
GEOS contributed important information on wind patterns and other natural weather fluctuations affecting CO2 emission and transport. “This study really is bringing everything together to attack an enormously difficult problem,” Ott said.
More of the ingredients for life have been found in meteorites.
Space rocks that fell to Earth within the last century contain the five bases that store information in DNA and RNA, scientists report April 26 in Nature Communications.
These “nucleobases” — adenine, guanine, cytosine, thymine and uracil — combine with sugars and phosphates to make up the genetic code of all life on Earth. Whether these basic ingredients for life first came from space or instead formed in a warm soup of earthly chemistry is still not known (SN: 9/24/20). But the discovery adds to evidence that suggests life’s precursors originally came from space, the researchers say.
Scientists have detected bits of adenine, guanine and other organic compounds in meteorites since the 1960s (SN: 8/10/11, SN: 12/4/20). Researchers have also seen hints of uracil, but cytosine and thymine remained elusive, until now.
“We’ve completed the set of all the bases found in DNA and RNA and life on Earth, and they’re present in meteorites,” says astrochemist Daniel Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Md.
A few years ago, geochemist Yasuhiro Oba of Hokkaido University in Sapporo, Japan, and colleagues came up with a technique to gently extract and separate different chemical compounds in liquified meteorite dust and then analyze them.
“Our detection method has orders of magnitude higher sensitivity than that applied in previous studies,” Oba says. Three years ago, the researchers used this same technique to discover ribose, a sugar needed for life, in three meteorites (SN: 11/22/19).
In the new study, Oba and colleagues combined forces with astrochemists at NASA to analyze one of those three meteorite samples and three additional ones, looking for another type of crucial ingredient for life: nucleobases.
The researchers think their milder extraction technique, which uses cold water instead of the usual acid, keeps the compounds intact. “We’re finding this extraction approach is very amenable for these fragile nucleobases,” Glavin says. “It’s more like a cold brew, rather than making hot tea.”
With this technique, Glavin, Oba and their colleagues measured the abundances of the bases and other compounds related to life in four samples from meteorites that fell decades ago in Australia, Kentucky and British Columbia. In all four, the team detected and measured adenine, guanine, cytosine, uracil, thymine, several compounds related to those bases and a few amino acids.
Using the same technique, the team also measured chemical abundances within soil collected from the Australia site and then compared the measured meteorite values with that of the soil. For some detected compounds, the meteorite values were greater than the surrounding soil, which suggests that the compounds came to Earth in these rocks.
But for other detected compounds, including cytosine and uracil, the soil abundances are as much as 20 times as high as in the meteorites. That could point to earthly contamination, says cosmochemist Michael Callahan of Boise State University in Idaho.
“I think [the researchers] positively identified these compounds,” Callahan says. But “they didn’t present enough compelling data to convince me that they’re truly extraterrestrial.” Callahan previously worked at NASA and collaborated with Glavin and others to measure organic materials in meteorites.
But Glavin and his colleagues point to a few specific detected chemicals to support the hypothesis of an interplanetary origin. In the new analysis, the researchers measured more than a dozen other life-related compounds, including isomers of the nucleobases, Glavin says. Isomers have the same chemical formulas as their associated bases, but their ingredients are organized differently. The team found some of those isomers in the meteorites but not in the soil. “If there had been contamination from the soil, we should have seen those isomers in the soil as well. And we didn’t,” he says.
Going directly to the source of such meteorites — pristine asteroids — could clear up the matter. Oba and colleagues are already using their extraction technique on pieces from the surface of the asteroid Ryugu, which Japan’s Hayabusa2 mission brought to Earth in late 2020 (SN: 12/7/20). NASA’s OSIRIS-REx mission is expected to return in September 2023 with similar samples from the asteroid Bennu (SN: 1/15/19).
“We’re really excited about what stories those materials have to tell,” Glavin says. [Reply]
Originally Posted by Fish:
This was a well done video.
I'm a big fan of that channel in general. It's pretty dense sometimes, but he's always very well researched, and the topics are almost always interesting. [Reply]
Originally Posted by DaFace:
I'm a big fan of that channel in general. It's pretty dense sometimes, but he's always very well researched, and the topics are almost always interesting.
He caused quite a stir a couple of months ago trying to explain how electromagnetism propagates [basically a hypothetical of a resistance-free pair of parallel wires connecting a light on the moon and switch to a battery here on earth], partially because it's a poorly understood phenomenon to begin with, and partially because he tried to explain it in lay terms.
The net benefit was a ton of experts put out some good material critiquing and correcting.
Not groundbreaking, but a quality update on some basics with top notch visualizations and a decently layman presentation. . . BBC production on how size affects our understanding of the laws of nature.
