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Thanksgiving special: Dinosaur drumsticks and the story of the turkey trot

The new dinosaur is called Tralkasaurus, which means "thunder reptile" in the indigenous Mapuche language common in Patagonia. In this file photo, a boy in Melbourne, Australia inspects the teeth of a theropod dinosaur
Representative image

Wings may be the obvious choice when studying the connection between dinosaurs and birds, but a pair of Yale paleontologists prefer drumsticks. That part of the leg, they say, is where fibular reduction among some dinosaurs tens of millions of years ago helped make it possible for peacocks to strut, penguins to waddle, and turkeys to trot.

“A good way to understand this is to take a look at drumsticks, like the ones people eat on Thanksgiving,” said Armita Manafzadeh, lead author of a new study in Nature. She is a postdoctoral researcher affiliated with the Yale Institute for Biospheric Studies, the Department of Earth & Planetary Science, and the Yale Peabody Museum.

“Under the meat of a drumstick, you’ll find two bones — the tibia, which is long and thick, and the fibula, which is much shorter and thinner,” Manafzadeh explained. “This shortened fibula is what allows birds to twist and turn around when they’re not in flight. And to understand its evolutionary story, we have to look at dinosaurs.”

Yet the fibula had been largely overlooked by paleontologists and other scientists, often viewed as merely a small remnant of a once-larger physiological feature. The idea that the shortened fibula had a distinct evolutionary benefit was relatively unexplored.

“The fibula is, in general, the more diminutive of the two lower leg bones, and often neglected in the study of vertebrate form and function,” said Bhart-Anjan Bhullar, associate professor of Earth and planetary sciences in Yale’s Faculty of Arts and Sciences, associate curator at the Yale Peabody Museum, and co-author of the study. “But evolution acts on all parts of the body, great and small. Structures and regions that have been ignored are often gold mines for new insights and untold tales.”

For the study, the researchers used X-ray videos of a present-day bird — a helmeted guineafowl — to precisely measure the knee-joint poses of the bird. Using cutting-edge computer animation software, they combined the videos with 3D models to visualize how the bird’s bone surfaces fit together geometrically and how those joints appeared in motion.

They also collected X-ray videos from an iguana and an alligator and examined the shapes of leg bones in other birds, including a penguin, an ostrich, an owl, and a crane.

The researchers found that in birds, the tibial joint surfaces have curved arcs, and the shortened fibula is able to roll within the bird’s drumstick for about its length relative to the tibia. Taken together, these features enable the knee bones to maintain smooth contact, even when the joint twists by more than 100 degrees.

“You can see that the fibula of birds is moving completely differently from that of other living reptiles,” Manafzadeh said. “It’s why their knees are uniquely able to spin, allowing them to navigate their world more effectively. They use that mobility to turn and maneuver on the ground, but we suspect they’re also using it in mating displays, prey gathering, and moving about tree branches.”

Next, the researchers searched for the evolutionary origins of the shortened fibula in birds — and found their answer in certain species of dinosaurs.

While many dinosaurs, including Tyrannosaurus rex, had straightened tibial surfaces and stiffened drumsticks that only allowed for hinge-like knees, certain avian ancestors, including Rahonavis ostromi and Ichthyornis dispar, showed indications of curved tibial surfaces and a shortened, thinner fibula that was free to move on its own.

“We found that the very features that appeared in early dinosaurs to stiffen the leg ended up being co-opted in birds and their close relatives to mobilize the knee joint in a unique and extreme way,” Bhullar said. “Over and again, we see that evolution operates by repurposing existing structures and functions, often in surprising and unpredictable ways.”

The researchers said several well-known Yale Peabody Museum fossils were pivotal in the work, including Allosaurus, the giant Jurassic predator discovered by O.C. Marsh (which had a stiffened dinosaurian knee); Deinonychus, the “velociraptor” of the “Jurassic Park” films (which had an early form of the birdlike knee joint); and Ichthyornis, whose proto-beak was the subject of an earlier study by Bhullar (and which had a fully modern, avian knee).

The new study is part of Bhullar and Manafzadeh’s ongoing research into the evolution of animal motion, based on their novel method for visualizing how ancient animals moved by comparing their joints with those of modern animals.

Reference:
Armita R. Manafzadeh, Stephen M. Gatesy, John A. Nyakatura, Bhart-Anjan S. Bhullar. Fibular reduction and the evolution of theropod locomotion. Nature, 2024; DOI: 10.1038/s41586-024-08251-w

Note: The above post is reprinted from materials provided by Yale University. Original written by Jim Shelton.

Sliding seeds can provide insight into devastating landslides and rock avalanches

Sliding Champatis, the seeds of the Lapsi tree, can provide insight into devastating landslides and rock avalanches. Credit: Pudasaini et al.
Sliding Champatis, the seeds of the Lapsi tree, can provide insight into devastating landslides and rock avalanches. Credit: Pudasaini et al.

Champatis, the seeds of the Lapsi tree, are valued in Nepal for their medical, economic, social, and cultural significance. They are also popular among children as simple playthings. But for a group of physicists, these unique seeds — and the way they bounce and roll down slopes — could help them better understand landslides and avalanches, leading to research that could save lives.

In a study published this week in Physics of Fluids, by AIP Publishing, a team at the Technical University of Munich, the Kathmandu Institute of Complex Flows, and Tribhuvan University studied how Champatis roll and bounce down inclines.

They suggested these seeds could serve as an analogue in the study of geological flow, particularly in a region prone to landslides and avalanches.

The Champati has a very complex structure. The wide head and narrow oval tail create a slope for each grain, leading to spin and rolling motion when sliding down slopes.

This creates interesting dynamics that drew the attention of the research team.

“We are primarily interested in the scientific question of the dynamics and deposition of Champati slide: how it flows, where it goes, how far, and with what force,” said author Shiva Pudasaini from Kathmandu.

The authors released a heap of the seeds down an inclined plane while a camera recorded their descent to analyze their speed and the dynamics of their movement.

The unique physical and geometrical properties of the supergrain led to previously unobserved dynamics as they slid down slopes.

The team’s findings showed a unique property: The grains start to spread out slowly, then decrease quickly as they move downstream, akin to rock avalanches.

“Soon after the mass hits the ground, the behavior is unprecedented and appears to be highly unpredictable,” Pudasaini said.

This research may provide valuable insights into geological flows, including hyperspreading of rock avalanches, and could contribute to resolving challenges in this area.

Additionally, findings may have significant implications for industrial process engineering.

Currently, the advanced mechanical, geotechnical, and imaging technologies needed for further study of the Champati seeds are not fully available in Kathmandu.

To address this, the research team is expanding their measurement facilities and collaborating with well-equipped research institutions abroad.

However, while the initial results offer promising insights into fragmented rock avalanches, further investigation into the structural, mechanical, and dynamic properties of these grains is essential to fully understand their relevance to earth science and engineering.

Reference:
Shiva P. Pudasaini, Bekha R. Dangol, Chet N. Tiwari, Jeevan Kafle, Puskar R. Pokhrel, Parameshwari Kattel. The Champati Slide. Physics of Fluids, 2024; 36 (11) DOI: 10.1063/5.0230878

Note: The above post is reprinted from materials provided by American Institute of Physics

How 70% of the Mediterranean Sea was lost 5.5 million years ago

The two accumulation phases of the Mediterranean salt layer during the Messinian Salinity Crisis. In the first phase, salt accumulated in a Mediterranean Basin filled with brine; in the second phase, salt accumulated in a Mediterranean completely isolated from the Atlantic Ocean, as a result of the significant drop in sea level in the western and eastern Mediterranean sub-basins. © Giovanni Aloisi
The two accumulation phases of the Mediterranean salt layer during the Messinian Salinity Crisis. In the first phase, salt accumulated in a Mediterranean Basin filled with brine; in the second phase, salt accumulated in a Mediterranean completely isolated from the Atlantic Ocean, as a result of the significant drop in sea level in the western and eastern Mediterranean sub-basins. © Giovanni Aloisi

Mediterranean Sea dropped during the Messinian Salinity Crisis — a major geological event that transformed the Mediterranean into a gigantic salt basin between 5.97 and 5.33 million years ago.

Until now, the process by which a million cubic kilometres of salt accumulated in the Mediterranean basin over such a short period of time remained unknown.

Thanks to analysis of the chlorine isotopes contained in salt extracted from the Mediterranean seabed, scientists have been able to identify the two phases of this extreme evaporation event.

During the first phase, lasting approximately 35 thousand years, salt deposition occurred only in the eastern Mediterranean, triggered by the restriction of Mediterranean outflow to the Atlantic, in an otherwise brine-filled Mediterranean basin.

During the second phase, salt accumulation occurred across the entire Mediterranean, driven by a rapid (< 10 thousand years) evaporative drawdown event during which sea-level dropped 1.7-2.1 km and ~0.85 km in the eastern and western Mediterranean, respectively.

As a result, the Mediterranean Basin lost up to 70% of its water volume.

This spectacular fall in sea level is thought to have had consequences for both terrestrial fauna and the Mediterranean landscape — triggering localised volcanic eruptions due to unloading of Earth’s crust, as well as generating global climatic effects due to the huge depression caused by the sea-level drawdown.

These results, published in Nature Communications on November 18, provide a better understanding of past extreme geological phenomena, the evolution of the Mediterranean region and successive global repercussions.

This work was supported by the European Union and the CNRS.

Notes :

  1. From the French research institute Institut de physique du globe de Paris (CNRS/Université Paris Cité/Institut de physique du globe de Paris).
  2. This exceptional event covered the floor of the Mediterranean Sea with a layer of salt up to 3 km thick. Understanding the causes, consequences and environmental changes undergone by the Mediterranean region in response to the Messinian Salinity Crisis is a challenge that has mobilised the scientific community for decades.
  3. Analysis of the two stable chlorine isotopes (³⁷Cl and ³⁵Cl) made it possible to estimate the rate of salt accumulation and detect the drop in sea level.

Reference:
G. Aloisi, J. Moneron, L. Guibourdenche, A. Camerlenghi, I. Gavrieli, G. Bardoux, P. Agrinier, R. Ebner, Z. Gvirtzman. Chlorine isotopes constrain a major drawdown of the Mediterranean Sea during the Messinian Salinity Crisis. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-53781-6

Note: The above post is reprinted from materials provided by CNRS.

New research explores volcanic caves, advancing the search for life on Mars

White microbial-like colonies on the lava tube substrate.
White microbial-like colonies on the lava tube substrate.

Through the intricate study of lava tubes — caves formed following volcanic eruptions when lava cools down — an international team of researchers has uncovered clues about Earth’s ancient environments that could be significant in the search for life on Mars.

Bogdan P. Onac, professor in the USF School of Geosciences, collaborated with researchers from Portugal, Spain and Italy to shed light on how lava tubes may serve as valuable analogs for Martian caves and the search for extraterrestrial life.

On the Spanish island of Lanzarote, just west of North Africa, the team explored six lava tubes to gather mineral deposits.

Some of the tubes are so large, they are used to host underground concerts.

“While the lava tubes on Lanzarote were discovered several years ago, we are the first to complete such a detailed study of minerals and microorganisms,” Onac said.

In the study, published in Communications Earth & Environment, Onac and the team used a range of advanced molecular, isotopic and mineralogical techniques to examine the deposits and create a comprehensive understanding of the minerals they held.

They learned the volcanic rock in the lava tubes created a protective environment that helped shield the minerals and organic compounds from weathering, ultimately preserving the minerals as records of past ecosystems.

The team found preserved biosignatures, including calcium and sodium sulfates.

This discovery indicates microbial activity and microorganisms, such as bacteria, were once active in the caves.

“This study adds to our understanding of geological and environmental changes on Earth and highlights lava tubes as potential refuges for microbial life, holding significant implications for astrobiology, particularly in identifying biosignatures on Mars and other celestial bodies,” Onac said.

Given that Martian lava tubes are similarly shielded and likely contain sulfate-rich minerals, they may also hold signs of past microbial life, giving us clues about potential life beyond Earth.

The findings may significantly impact the way scientists approach planetary exploration, particularly for upcoming missions aimed at studying the habitability of Mars.

The team will publish several additional studies on these lava tubes in the coming months and they are also planning to examine newly formed lava tubes in Iceland.

Reference:
Vera Palma, José María De la Rosa, Bogdan Petroniu Onac, Francesco Sauro, Jesús Martínez-Frías, Ana Teresa Caldeira, José Antonio González-Pérez, Nicasio Tomás Jiménez-Morillo, Ana Zélia Miller. Decoding organic compounds in lava tube sulfates to understand potential biomarkers in the Martian subsurface. Communications Earth & Environment, 2024; 5 (1) DOI: 10.1038/s43247-024-01673-4

Note: The above post is reprinted from materials provided by University of South Florida. Original written by Cassidy Delamarter.

Scientists compile library for evaluating exoplanet water

A polarized microscope photo of basaltic rock. Credit: Esteban Gazel Lab/Provided
A polarized microscope photo of basaltic rock. Credit: Esteban Gazel Lab/Provided

By probing chemical processes observed in the Earth’s hot mantle, Cornell scientists have started developing a library of basalt-based spectral signatures that not only will help reveal the composition of planets outside of our solar system but could demonstrate evidence of water on those exoplanets.

“When the Earth’s mantle melts, it produces basalts,” said Esteban Gazel, professor of engineering. Basalt, a gray-black volcanic rock found throughout the solar system, are key recorders of geologic history, he said.

“When the Martian mantle melted, it also produced basalts. The moon is mostly basaltic,” he said. “We’re testing basaltic materials here on Earth to eventually elucidate the composition of exoplanets through the James Webb Space Telescope data.”

Gazel and Emily First, a former Cornell postdoctoral researcher and now an assistant professor at Macalester College in Minnesota, are authors of “Mid-infrared Spectra for Basaltic Rocky Exoplanets,” on November 14 in Nature Astronomy.

Understanding how minerals record the processes that created these rocks, and their spectroscopic signatures is the first step in developing their library, Gazel said.

“We know that the majority of exoplanets will produce basalts, given that their host star metallicity will result in mantle minerals (iron-magnesium silicates) so that when they melt, phase equilibria (equilibrium between two states of matter) predicts that the resulting lavas will be basaltic,” Gazel said. “It will be prevalent not only in our solar system, but throughout the galaxy, too.”

First measured the emissivity — the extent to which a surface radiates the energy it encounters — of 15 basaltic samples for spectral signatures of what the space telescope’s mid-infrared spectrometer may detect.

Once basaltic melts erupt on an exoplanet and cool down, the basalts harden into solid rock, known on Earth as lava. This rock can interact with water, if present, which forms new hydrated minerals easy to spot in the infrared spectra. These altered minerals could become amphibole (a hydrous silicate) or serpentine (another hydrous silicate, which looks like a snake’s skin).

By examining small spectral differences between the basalt samples, scientists can in theory determine whether an exoplanet once had running surface water or water in its interior, said Gazel.

Proof of water does not emerge instantly, and further work is needed before this type of detection can be employed. It would take the James Webb Space Telescope (JWST) — about 1 million miles from Earth — dozens to hundreds of hours to focus on one system light-years away, then more time to analyze the data.

The research group — in looking for a rocky exoplanet to simulate its hypotheses and consider the 15 different signatures — used data from the super Earth exoplanet LHS 3844b, which orbits a red dwarf a little more than 48 light-years away.

Ishan Mishra, working in the laboratory of Nikole Lewis, associate professor of astronomy, wrote computer code modeling First’s spectral data to simulate how differing exoplanet surfaces might appear to the JWST.

Lewis said that modeling tools were first used for other applications. “Ishan’s coding tools were used originally for studying icy moons in the solar system,” she said. “We are now finally trying to translate what we’ve learned of the solar system into exoplanets.”

“The goal was not to assess planet LHS 3844b specifically,” First said, “but rather to consider a plausible range of basaltic rocky exoplanets that could be observed by JWST and other observatories in the coming years.”

In terms of exoplanets, the researchers said exploration of rocky surfaces has been mostly limited to single data points — finding evidence of only type of chemical — in the scientific literature, but that is changing to multiple components as observers make use of the JWST.

By trying to tease out signatures related to mineralogy and bulk chemical composition — for example, how much silicon, aluminum and magnesium are in a rock — the geologists can tell a little more about the conditions under which the rock formed, the geologists said.

“On Earth, if you have basaltic rocks erupting from mid-ocean ridges deep on the ocean floor, versus those erupting at ocean islands like Hawaii,” First said, “you will notice some differences in the bulk chemistry. But even rocks of similar bulk chemistry can contain different minerals, so these are both important characteristics to examine.”

In addition to First, Gazel, Lewis and Mishra, co-authors are Jonathan Letai ’23, Northeastern University; and physicist Leonard Hanssen, Ph.D. ’85, recently retired from the National Institute of Standards and Technology.

Lewis is a faculty fellow in Cornell’s Carl Sagan Institute.

The National Science Foundation, the National Institute of Standards and Technology and the Heising-Simons Foundation/51 Pegasi b Fellowship supported this research.

Reference:
Emily C. First, Ishan Mishra, Esteban Gazel, Nikole K. Lewis, Jonathan Letai, Leonard Hanssen. Potential for observing geological diversity from mid-infrared spectra of rocky exoplanets. Nature Astronomy, 2024; DOI: 10.1038/s41550-024-02412-7

Note: The above post is reprinted from materials provided by Cornell University. Original written by Blaine Friedlander, Cornell Chronicle.

Bird brain from the age of dinosaurs reveals roots of avian intelligence

Artist’s impression of Navaornis. Credit: Júlia D’Oliveira
Artist’s impression of Navaornis. Credit: Júlia D’Oliveira

A ‘one of a kind’ fossil discovery could transform our understanding of how the unique brains and intelligence of modern birds evolved, one of the most enduring mysteries of vertebrate evolution.

Researchers have identified a remarkably well-preserved fossil bird, roughly the size of a starling, from the Mesozoic Era. The complete skull has been preserved almost intact: a rarity for any fossil bird, but particularly for one so ancient, making this one of the most significant finds of its kind.

The extraordinary three-dimensional preservation of the skull allowed the researchers, led by the University of Cambridge and the Natural History Museum of Los Angeles County, to digitally reconstruct the brain of the bird, which they have named Navaornis hestiae. Navaornis lived approximately 80 million years ago in what is now Brazil, before the mass extinction event that killed all non-avian dinosaurs.

The researchers say their discovery, reported in the journal Nature, could be a sort of ‘Rosetta Stone’ for determining the evolutionary origins of the modern avian brain. The fossil fills a 70-million-year gap in our understanding of how the brains of birds evolved: between the 150-million-year-old Archaeopteryx, the earliest known bird-like dinosaur, and birds living today.

Navaornis had a larger cerebrum than Archaeopteryx, suggesting it had more advanced cognitive capabilities than the earliest bird-like dinosaurs. However, most areas of its brain, like the cerebellum, were less developed, suggesting that it hadn’t yet evolved the complex flight control mechanisms of modern birds.

“The brain structure of Navaornis is almost exactly intermediate between Archaeopteryx and modern birds — it was one of these moments in which the missing piece fits absolutely perfectly,” said co-lead author Dr Guillermo Navalón from Cambridge’s Department of Earth Sciences.

Navaornis is named after William Nava, director of the Museu de Paleontologia de Marília in Brazil’s São Paolo State, who discovered the fossil in 2016 at a site in the neighbouring locality of Presidente Prudente. Tens of millions of years ago, this site was likely a dry area with slow-flowing creeks, which enabled the fossil’s exquisite preservation. This preservation allowed the researchers to use advanced micro-CT scanning technology to reconstruct the bird’s skull and brain in remarkable detail.

“This fossil is truly so one-of-a-kind that I was awestruck from the moment I first saw it to the moment I finished assembling all the skull bones and the brain, which lets us fully appreciate the anatomy of this early bird,” said Navalón.

“Modern birds have some of the most advanced cognitive capabilities in the animal kingdom, comparable only with mammals,” said Professor Daniel Field from Cambridge’s Department of Earth Sciences, senior author of the research. “But scientists have struggled to understand how and when the unique brains and remarkable intelligence of birds evolved — the field has been awaiting the discovery of a fossil exactly like this one.”

Before this discovery, knowledge of the evolutionary transition between the brains of Archaeopteryx and modern birds was practically non-existent. “This represents nearly 70 million years of avian evolution in which all the major lineages of Mesozoic birds originated — including the first representatives of the birds that live today,” said Navalón. “Navaornis sits right in the middle of this 70-million-year gap and informs us about what happened between these two evolutionary points.”

While the skull of Navaornis somewhat resembles that of a small pigeon at first glance, closer inspection reveals that it is not a modern bird at all but instead a member of a group of early birds named enantiornithines, or the ‘opposite birds.’

‘Opposite birds’ diverged from modern birds more than 130 million years ago, but had complex feathers and were likely competent flyers like modern birds. However, the brain anatomy of Navaornis poses a new question: how did opposite birds control their flight without the full suite of brain features observed in living birds, including an expanded cerebellum, which is a living bird’s spatial control centre?

“This fossil represents a species at the midpoint along the evolutionary journey of bird cognition,” said Field, who is also the Strickland Curator of Ornithology at Cambridge’s Museum of Zoology. “Its cognitive abilities may have given Navaornis an advantage when it came to finding food or shelter, and it may have been capable of elaborate mating displays or other complex social behaviour.”

“This discovery shows that some of the birds flying over the heads of dinosaurs already had a fully modern skull geometry more than 80 million years ago,” said co-lead author Dr Luis Chiappe from the Natural History Museum of Los Angeles County.

While Navaornis is one of the best-preserved bird fossils ever found from the Mesozoic Era, the researchers believe many more finds from the Brazilian site where it was found could offer further insights into bird evolution.

“This might be just one fossil, but it’s a key piece in the puzzle of bird brain evolution,” said Field. “With Navaornis, we’ve got a clearer view of the evolutionary changes that occurred between Archaeopteryx and today’s intelligent, behaviourally complex birds like crows and parrots.”

While the discovery is a significant breakthrough, the researchers say it is only the first step in understanding the evolution of bird intelligence. Future studies may reveal how Navaornis interacted with its environment, helping to answer broader questions about the evolution of bird cognition over time.

Navaornis is the most recent in a quartet of Mesozoic fossil birds described by Field’s research group since 2018, joining Ichthyornis, Asteriornis (the ‘Wonderchicken’), and Janavis. The group’s work on new fossil discoveries combined with advanced visualisation and analytical techniques have revealed fundamental insights into the origins of birds, the most diverse group of living vertebrate animals.

The research was supported in part by UK Research and Innovation (UKRI). Daniel Field is a Fellow of Christ’s College, Cambridge.

Reference:
Luis M. Chiappe, Guillermo Navalón, Agustín G. Martinelli, Ismar de Souza Carvalho, Rodrigo Miloni Santucci, Yun-Hsin Wu, Daniel J. Field. Cretaceous bird from Brazil informs the evolution of the avian skull and brain. Nature, 2024; DOI: 10.1038/s41586-024-08114-4

Note: The above post is reprinted from materials provided by University of Cambridge. Original written by Sarah Collins. The original text of this story is licensed under a Creative Commons License.

Did the world’s best-preserved dinosaurs really die in ‘Pompeii-type’ events?

Two perfectly articulated skeletons of the sheep-size dinosaur Psittacosaurus, found in China’s Yixian Formation. New research suggests they died in burrow collapses, not via volcanism, as previously thought. (Jun Liu, Institute of Paleontology and Paleoanthropology, Chinese Academy of Sciences)
Two perfectly articulated skeletons of the sheep-size dinosaur Psittacosaurus, found in China’s Yixian Formation. New research suggests they died in burrow collapses, not via volcanism, as previously thought. (Jun Liu, Institute of Paleontology and Paleoanthropology, Chinese Academy of Sciences)

Between about 120 million and 130 million years ago, during the age of dinosaurs, temperate forests and lakes hosted a lively ecosystem in what is now northeast China. Diverse fossils from that time remained pretty much undisturbed until the 1980s, when villagers started finding exceptionally preserved creatures, which fetched high prices from collectors and museums. This started a fossil gold rush. Both locals and scientists have now dug so much, their work can be seen from space — perhaps the most extensive paleontological excavations anywhere.

By the 1990s, it was clear that the so-called Yixian Formation contained uniquely well preserved remains of dinosaurs, birds, mammals, insects, frogs, turtles and other creatures. Unlike the skeletal and often fragmentary fossils unearthed in most other places, many animals came complete with internal organs, feathers, scales, fur and stomach contents. It suggested some kind of sudden, unusual preservation process at work. The finds even included a cat-size mammal and a small dinosaur locked in mortal combat, stopped in mid-action when they died. The world’s first known non-avian feathered dinosaurs showed up — some so intact that scientists worked out the feathers’ colors. The discoveries revolutionized paleontology, clarifying the evolution of feathered dinosaurs, and proving without a doubt that modern birds are descended from them.

How did these fossils come to be so perfect? The leading hypothesis up to now has been sudden burial by volcanism, perhaps like the waves of hot ash from Mt. Vesuvius that entombed many citizens of Pompeii in A.D. 79. The Yixian deposits have been popularly dubbed the “Chinese Pompeii.”

A new study says the Pompeii idea is highly appealing — and totally wrong. Instead, the creatures were preserved by more mundane events including collapses of burrows and rainy periods that built up sediments that buried the dead in oxygen-free pockets. Earlier studies have suggested that multiple Pompeii-type events took place in pulses over about a million years. The current study uses newly sophisticated technology to date the fossils to a compact period of less than 93,000 years when nothing particular happened.

The study was just published in the journal Proceedings of the National Academy of Sciences.

“These are probably the most important dinosaur discoveries of the last 120 years,” said study coauthor Paul Olsen, a paleontologist at the Columbia Climate School’s Lamont-Doherty Earth Observatory. “But what was said about their method of preservation highlights an important human bias. That is, to ascribe extraordinary causes, i.e. miracles, to ordinary events when we don’t understand their origins. These [fossils] are just a snapshot of everyday deaths in normal conditions over a relatively brief time.”

The Yixian Formation fossils come in two basic varieties: intact, perfectly articulated 3D skeletons from deposits formed mainly on land, and flattened but highly detailed carcasses found in lake sediments, some containing soft tissues.

To come up with fossil ages, the study’s lead author, Scott MacLennan of South Africa’s University of the Witwatersrand, analyzed tiny grains of the mineral zircon, taken from both surrounding rocks and the fossils themselves. Within these, he measured ratios of radioactive uranium against lead, using a new, extremely precise method called chemical abrasion isotope dilution thermal ionization mass spectroscopy, or CA-ID-TIMS. The fossils and surrounding material consistently dated to 125.8 million years ago, centered around a period of less than 93,000 years, though the exact number is not clear.

Further calculations showed that this timeframe contained three periods controlled by variations in the Earth’s orbit when the weather was relatively wet. This caused sediments to build up in lakes and on land far more rapidly than previously had been thought. Many deceased creatures were quickly buried, and oxygen that normally would fuel decomposition was sealed out. The sealing effect was fastest in lakes, resulting in the preservation of soft tissues.

The researchers rule out volcanism on multiple counts. Some previous studies have suggested that creatures were encased by lahars, fast-moving concrete-like slurries of mud that flow off volcanoes following eruptions. But lahars are extremely violent, said Olsen, and apt to rip apart any living or dead thing they encounter, so this explanation does not work.

Others have said pyroclastic flows — fast-moving waves of searing ash and poisonous gases á la Mt. Vesuvius — were responsible. These struck down residents of Pompeii, then wrapped the bodies in protective layers of material that preserved them as they were at the moment of death. Even when remains decayed, voids in the ashes remained, from which investigators have made lifelike plaster casts. The remains characteristically are curled in so-called pugilistic positions, torturously doubled over and with limbs severely drawn up, as blood boiled and bodies crumpled in the explosive heat. Victims of modern fires exhibit similar poses.

While there are in fact layers of volcanic ash, lava and intrusions of magma in the Yixian Formation, the remains there don’t match those of the unfortunate Pompeiians. For one thing, feathers, fur and everything else would almost certainly have been burned in a pyroclastic flow. For another, the dinosaurs and other animals are not in pugilistic positions; rather, many are found with arms and tails tucked cozily around their bodies, as if they were sleeping, perhaps dreaming dinosaur dreams, when death found them.

The evidence points instead to sudden burrow collapses, say the researchers. Cores of rock surrounding the skeletonized fossils generally consist of coarse grains, but grains immediately around and within the skeletons tend to be much finer. The researchers interpret this to mean that there was enough oxygen around for a while for bacteria or insects to degrade at least the animals’ skin and organs, and as this happened, whatever fine grains were in the surrounding material preferentially seeped in and filled the voids; the more decay-resistant bones remained intact. Even today, burrow collapses are a common cause of death for birds such as penguins, said Olsen. The frozen-in-time mammal-dinosaur battle may well have happened as the mammal invaded the dinosaur’s burrow to try and eat it or its babies, he said.

As to what caused the burrow collapses, this is speculation, he said. One thought: bigger dinosaurs (whose remains don’t appear here but who were almost certainly around) could have squished burrows simply by tromping around. Exceptionally rainy times could have helped destabilize the ground.

Olsen believes the Yixian Formation is not unique. “It’s just that there is no place else where such intense collecting has been done in this kind of environment,” he said. China has tried to limit for-profit fossil sales, but the market is still thriving, and huge government resources are going into development of tourism around the fossil sites.

Olsen’s personal Holy Grail is feathered dinosaurs, but these are exceedingly rare even in the richest deposits, he pointed out. “You have to dig out, say, 100,000 fish to find one feathered dinosaur, and no one is digging on the Yixian scale,” he said. Just in the eastern United States, several places that once had environments similar to the Yixian could yield such fossils, Olsen said. These include a rock quarry straddling the North Carolina-Virginia border where he has found thousands of perfectly preserved insects; sites in Connecticut where small excavations have shown promise; and a former quarry in North Bergen, N.J., now sandwiched between a highway and a strip mall that in the past yielded fabulously preserved fish and reptiles. Systematic excavations of such spots are more or less the size of a bathroom, he said.

“It takes enormous effort, which is expensive. And land is valuable in these areas,” he said. “So no one is doing it. At least not yet.”

The study was coauthored by Sean Kinney and Clara Chang of Lamont-Doherty Earth Observatory, and researchers from the Nanjing Institute of Geology and Paleontology, the Institute of Paleontology and Paleoanthropology at the Chinese Academy of Sciences, and Princeton University.

Reference:
Scott A. MacLennan, Jingeng Sha, Paul E. Olsen, Sean T. Kinney, Clara Chang, Yanan Fang, Jun Liu, Bennett B. Slibeck, Elaine Chen, Blair Schoene. Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China. Proceedings of the National Academy of Sciences, 2024; 121 (47) DOI: 10.1073/pnas.2322875121

Note: The above post is reprinted from materials provided by Columbia Climate School. Original written by Kevin Krajick.

White smokers on the lake floor

An individual submarine chimney at a depth of roughly 30 m.Photo: UFZ
An individual submarine chimney at a depth of roughly 30 m.
Photo: UFZ

In an interdisciplinary research project coordinated by the Helmholtz Centre for Environmental Research (UFZ), researchers have discovered meter-high chimneys on the floor of the Dead Sea. These are formed by the spontaneous crystallization of minerals from groundwater with an extremely high salt content flowing up out of the lake floor, they report in journal Science of the Total Environment. Discovered for the first time, these vents are an important early warning indicator for sinkholes. These subsidence craters form in the area surrounding the Dead Sea and pose a significant hazard to the population.

The Dead Sea is a highly dynamic system: Its level has been dropping by roughly one meter per year for more than 50 years, because it is cut off from key tributaries and is losing large quantities of water through evaporation as a result of drought and heat. The surface has thus dropped to roughly 438 meters below sea level. This decline in the lake, which borders Israel, Jordan and the West Bank under Palestinian administration, has significant consequences, especially for the groundwater. The groundwater level is falling, making it increasingly difficult for neighbouring countries to access groundwater resources. For many years, UFZ hydrogeologist Dr. Christian Siebert has been researching how the dynamics of the groundwater system in this region are changing and how aquifers are finding new paths in the rock strata both on land and below the Dead Sea. A team of divers he deployed has now discovered chimney-shaped vents on the lake floor that discharge a shimmering fluid.

“These bear a striking similarity to black smokers in the deep sea, but the system is completely different,” says the UFZ researcher. Scientists from the fields of mineralogy, geochemistry, geology, hydrology, remote sensing, microbiology and isotope chemistry from a total of ten research institutions were involved in investigating and analysing the phenomenon.

While black smokers along the mid-ocean ridge emit hot water containing sulphides at a depth of several thousand metres, the researchers in the Dead Sea discovered that highly saline groundwater flows out through the chimneys at the bottom of the lake. But where is the salt coming from? The explanation: The groundwater from the surrounding aquifers penetrates into the saline lake sediments, leaching out extremely old and thick layers of rock consisting mainly of the mineral halite. It then flows into the lake as brine.

“Because the density of this brine is somewhat lower than that of the water in the Dead Sea, it rises upwards like a jet. It looks like smoke, but it’s a saline fluid,” explains Christian Siebert.

Contact with the lake water causes the dissolved salts, especially the halite, to spontaneously crystallize after emerging from the lake bed, where it forms the vents observed for the first time in the world. These can grow by several centimetres within a single day. Many of the slender chimneys were one to two meters high, but they also include giants more than seven meters high, with a diameter of more than 2-3 meters. Minuscule traces of 36Cl, a radioisotope from space, and the genetic verification of freshwater microbes in the water from the chimneys have shown that the white smokers have their origin in the aquifers in the surrounding area. The salts were thus not absorbed until the last few meters before the water entered the Dead Sea.

These white smokers are especially important because they can serve as an early warning indicator for sinkholes. These are subsidence craters up to 100 meters wide and up to 20 meters deep, thousands of which have formed along the Dead Sea in recent decades. They are formed by karstification of the subsoil, i.e. by the dissolution of massive layers of salt. This forms giant cavities above which the ground can collapse at any time.

“To date, no one can predict where the next sinkholes will occur. They are also life-threatening and pose a threat to agriculture and infrastructure,” says Christian Siebert. The research team was able to show that the chimneys had formed wherever the land surface subsequently collapsed over a large area and the karstification process had apparently been especially efficient.

“This makes the white smokers an outstanding forecasting tool for locating areas that are at risk of collapse in the near future,” he says. Autonomous watercraft equipped with multibeam echosounders or side-scanning sonar systems could be used to map the chimneys to a high degree of precision. “This would be the only method to date, and a highly efficient one, for identifying regions at risk of imminent collapse.”

Reference:
C. Siebert, D. Ionescu, U. Mallast, S. Merchel, B. Merkel, P. Möller, S. Pavetich, T. Pohl, T. Rödiger, Y. Yechieli. A new type of submarine chimneys built of halite. Science of The Total Environment, 2024; 955: 176752 DOI: 10.1016/j.scitotenv.2024.176752

Note: The above post is reprinted from materials provided by Helmholtz Centre for Environmental Research – UFZ.

Was ‘Snowball Earth’ a global event? Study delivers best proof yet

Reddish-brown bands of Tava sandstone cut through other rocks. (Credit: Liam Courtney-Davies)
Reddish-brown bands of Tava sandstone cut through other rocks. (Credit: Liam Courtney-Davies)

Geologists have uncovered strong evidence from Colorado that massive glaciers covered Earth down to the equator hundreds of millions of years ago, transforming the planet into an icicle floating in space.

The study, led by the University of Colorado Boulder, is a coup for proponents of a long-standing theory known as Snowball Earth. It posits that from about 720 to 635 million years ago, and for reasons that are still unclear, a runaway chain of events radically altered the planet’s climate. Temperatures plummeted, and ice sheets that may have been several miles thick crept over every inch of Earth’s surface.

“This study presents the first physical evidence that Snowball Earth reached the heart of continents at the equator,” said Liam Courtney-Davies, lead author of the new study and a postdoctoral researcher in the Department of Geological Sciences at CU Boulder.

The team will publish its findings in the Proceedings of the National Academy of Sciences. Co-authors include Rebecca Flowers, professor of geological sciences at CU Boulder, and researchers from Colorado College, the University of California, Santa Barbara and University of California, Berkeley.

The study zeroes in on the Front Range of Colorado’s Rocky Mountains. Here, a series of rocks nicknamed the Tavakaiv, or “Tava,” sandstones hold clues to this frigid period in Earth’s past, Courtney-Davies said.

The researchers used a dating technique called laser ablation mass spectrometry, which zaps minerals with lasers to release some of the atoms inside. They showed that these rocks had been forced underground between about 690 to 660 million years ago — in all likelihood from the weight of huge glaciers pressing down above them.

Courtney-Davies added that the study will help scientists understand a critical phase in not just the planet’s geologic history but also the history of life on Earth. The first multicellular organisms may have emerged in oceans immediately after Snowball Earth thawed.

“You have the climate evolving, and you have life evolving with it. All of these things happened during Snowball Earth upheaval,” he said. “We have to better characterize this entire time period to understand how we and the planet evolved together.”

Searching for snow

The term “Snowball Earth” dates back to a paper published in 1992 by American geologist Joseph Kirschvink.

Despite decades of research, however, scientists are yet to agree whether the entire globe actually froze. Geologists, for example, have discovered the fingerprints of thick ice from this time period along ancient coastal areas, but not within the interior of continents close to the equator.

Which is where Colorado enters the picture. At the time, the region didn’t sit at the northern latitudes where it does today. Instead, Colorado rested over the equator as a landlocked part of the ancient supercontinent Laurentia.

If glaciers formed here, scientists believe, then they could have formed anywhere.

Going deep

The search for that missing piece of the puzzle brought Courtney-Davies and his colleagues to the Tava sandstones. Today, these features poke up from the ground in a few locations along Colorado’s Front Range, most notably around Pikes Peak. To the untrained eye, they might seem like ordinary-looking yellow-brown rocks running in vertical bands less than an inch to many feet wide.

But for geologists, these features have an unusual history. They likely began as sands at the surface of Colorado at some point in the past. But then forces pushed them underground — like claws digging into the Earth’s crust.

“These are classic geological features called injectites that often form below some ice sheets, including in modern-day Antarctica,” Courtney-Davies said.

He wanted to find out if the Tava sandstones were also connected to ice sheets. To do that, the researchers calculated the ages of mineral veins that sliced through those features. They collected tiny samples of the minerals, which are rich in iron oxide (essentially, rust), then hit them with a laser. In the process, the minerals released small quantities of the radioactive element uranium. Because uranium atoms decay into lead at a constant rate, the team could use them as a sort of timekeeper for the planet’s rocks.

It was a Eureka moment: The group’s findings suggest that the Tava sandstone had been pushed underground at the time of Snowball Earth. The group suspects that, at the time, thick ice sheets formed over Colorado, exposing the sands to intense pressures. Eventually, and with nowhere else to go, they pushed down into the bedrock below.

“We’re excited that we had the opportunity to unravel the story of the only Snowball Earth deposits that have so far been identified in Colorado,” Flowers said.

The researchers aren’t done yet: If such features formed in Colorado during Snowball Earth, they probably formed in other spots around North America, too, Courtney-Davies said:

“We want to get the word out so that others try and find these features and help us build a more complete picture of Snowball Earth.”

Reference:
Liam Courtney-Davies, Rebecca M. Flowers, Christine S. Siddoway, Adrian Tasistro-Hart, Francis A. Macdonald. Hematite U-Pb dating of Snowball Earth meltwater events. Proceedings of the National Academy of Sciences, 2024; 121 (47) DOI: 10.1073/pnas.2410759121

Note: The above post is reprinted from materials provided by University of Colorado at Boulder. Original written by Daniel Strain.

When Earth was slushy

The research findings hint at vast rivers of glacial water rushing like a reverse tsunami from the land into the sea, then pooling on top of extra salty, extra dense ocean water. Photo courtesy of AdobeStock.
The research findings hint at vast rivers of glacial water rushing like a reverse tsunami from the land into the sea, then pooling on top of extra salty, extra dense ocean water. Photo courtesy of AdobeStock.

At the end of the last global ice age, the deep-frozen Earth reached a built-in limit of climate change and thawed into a slushy planet.

Results from a Virginia Tech-led study provide the first direct geochemical evidence of the slushy planet — otherwise known as the “plumeworld ocean” era — when sky-high carbon dioxide levels forced the frozen Earth into a massive, rapid melting period.

“Our results have important implications for understanding how Earth’s climate and ocean chemistry changed after the extreme conditions of the last global ice age,” said lead author Tian Gan, a former Virginia Tech postdoctoral researcher. Gan worked with geologist Shuhai Xiao on the study, which was released Nov. 5 in the Proceedings of the National Academy of Sciences journal.

Deep-frozen Earth

The last global ice age took place about 635 million to 650 million years ago, when scientists believe global temperatures dropped and the polar ice caps began to creep around the hemispheres. The growing ice reflected more sunlight away from the Earth, setting off a spiral of plunging temperatures.

“A quarter of the ocean was frozen due to extremely low carbon-dioxide levels,” said Xiao, who recently was inducted into the National Academy of Sciences.

When the surface ocean sealed, a chain of reactions stuttered to a stop:

  • The water cycle locked up. No evaporation and very little rain or snow.
  • Without water, there was a massive slowdown in a carbon-dioxide consuming process called chemical weathering, where rocks erode and disintegrate.
  • Without weathering and erosion, carbon dioxide began to amass in the atmosphere and trap heat.

“It was just a matter of time until the carbon-dioxide levels were high enough to break the pattern of ice,” Xiao said. “When it ended, it probably ended catastrophically.”

Plume world

Suddenly, heat started to build. The ice caps began to recede, and Earth’s climate backpedaled furiously toward the drippy and soupy. Over a mere 10 million years, average global temperatures swung from minus 50 to 120 degrees Fahrenheit (minus 45 to 48 degrees Celsius).

But the ice didn’t melt and remix with seawater at the same time. The research findings paint a very different world than what we can imagine: vast rivers of glacial water rushing like a reverse tsunami from the land into the sea, then pooling on top of extra salty, extra dense ocean water.

The researchers tested this version of the prehistoric world by looking at a set of carbonate rocks that formed as the global ice age was ending.

They analyzed a certain geochemical signature, the relative abundance of lithium isotopes, recorded within the carbonate rocks. According to plumeworld ocean theory, the geochemical signatures of freshwater would be stronger in rocks formed under nearshore meltwater than in the rocks formed offshore, beneath the deep, salty sea — and that’s exactly what the researchers observed.

The findings bring the limit of environmental change into better focus, said Xiao, but they also give researchers additional insight into the frontiers of biology and the resiliency of life under extreme conditions — hot, cold, and slushy.

Study collaborators include:

  • Ben Gill, Virginia Tech associate professor of sedimentary geochemistry
  • Morrison Nolan, former graduate student, now at Denison University
  • Collaborators from the Chinese Academy of Sciences, University of Maryland at College Park, University of Munich in Germany, University of North Carolina at Chapel Hill, and University of Nevada at Las Vegas

Reference:
Tian Gan, Meng Tian, Xi-Kai Wang, Shijie Wang, Xiao-Ming Liu, Ganqing Jiang, Benjamin C. Gill, Morrison Nolan, Alan J. Kaufman, Taiyi Luo, Shuhai Xiao. Lithium isotope evidence for a plumeworld ocean in the aftermath of the Marinoan snowball Earth. Proceedings of the National Academy of Sciences, 2024; 121 (46) DOI: 10.1073/pnas.2407419121

Note: The above post is reprinted from materials provided by Virginia Tech. Original written by Kelly Izlar.

New trigger proposed for record-smashing 2022 Tonga eruption

The origins of the massive January 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption may have been detected in a seismic wave recorded 750 kilometers from the volcano, according to new research in Geophysical Research Letters. Credit: NASA
The origins of the massive January 2022 Hunga Tonga-Hunga Ha’apai volcanic eruption may have been detected in a seismic wave recorded 750 kilometers from the volcano, according to new research in Geophysical Research Letters. Credit: NASA

Fifteen minutes before the massive January 2022 eruption of the Hunga Tonga-Hunga Ha’apai volcano, a seismic wave was recorded by two distant seismic stations. Now, researchers argue that similar early signals could be used to warn of other impending eruptions in remote oceanic volcanoes.

The researchers propose that the seismic wave was caused by a fracture in a weak area of oceanic crust beneath the volcano’s caldera wall. That fracture allowed seawater and magma to pour into and mix together in the space above the volcano’s subsurface magma chamber, explosively kickstarting the eruption.

The research was published in Geophysical Research Letters, an open-access AGU journal that publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences.

The results build on the researchers’ previous work monitoring remote volcanoes. In this case, the Rayleigh wave, a type of seismic wave that moves through the Earth’s surface, was detected 750 kilometers (approximately 466 miles) from the volcano.

“Early warnings are very important for disaster mitigation,” said Mie Ichihara, a volcanologist at the University of Tokyo and one of the study’s coauthors. “Island volcanoes can generate tsunamis, which are a significant hazard.”

Silent precursor to a violent eruption

Hunga Tonga-Hunga Ha’apai is an oceanic volcano in the western Pacific Ocean in the Kingdom of Tonga. The seamount was created by the subduction of the Pacific Plate underneath the Australian Plate, a process that generates magma and leads to eruptions.

On January 15, 2022, the volcano erupted with record-breaking energy, injecting 58,000 Olympic swimming pools of water vapor into the stratosphere, setting off an unprecedented lightning storm and generating a tsunami. That massive eruption was preceded by a smaller eruption on January 14 and, before that, a month of eruptive activity.

Researchers still debate the exact start time of the eruption, though most agree that the eruption started shortly after 4:00 Coordinated Universal Time (UTC). The new study reports a Rayleigh wave that started around 3:45 UTC.

The researchers used seismic data to analyze the Rayleigh wave, which was detected by instruments, but not felt by humans, at seismic stations on the islands of Fiji and Futuna. While Rayleigh waves are a common feature of volcanic eruptions and earthquakes, the researchers believe that this wave signified a precursor event and possible cause of the massive eruption.

“Many eruptions are preceded by seismic activity,” said Takuro Horiuchi, a volcanology graduate student at the University of Tokyo and the lead author of the study. “However, such seismic signals are subtle and only detected within several kilometers of the volcano.”

In contrast, this seismic signal traveled a great distance, indicating a huge seismic event. “We believe unusually large movements started at the time of the precursor,” Horiuchi said.

Secrets of the seamount

Scientists may never know exactly what caused the gigantic, “caldera-forming” eruption, but Ichihara believes that the process was not instantaneous. Instead, she thinks that this precursor event was the start of an underground process that ultimately led to the eruption.

But it can be difficult to nail down the origins of these rare, colossal eruptions.

“There are very few observed caldera-forming eruptions, and there are even fewer witnessed caldera-forming eruptions in the ocean,” Ichihara said. “This gives one scenario about the processes leading to caldera formation, but I wouldn’t say that this is the only scenario.”

Regardless, detecting early eruption signals may give island nations and coastal areas more valuable time to prepare when faced with imminent tsunamis — even when the signal cannot be felt on the surface.

“At the time of the eruption, we didn’t think of using this kind of analysis in real-time,” Ichihara said. “But maybe the next time that there is a significant eruption underwater, local observatories can recognize it from their data.”

Reference:
Takuro Horiuchi, Mie Ichihara, Kiwamu Nishida, Takayuki Kaneko. A Seismic Precursor 15 min Before the Giant Eruption of Hunga Tonga‐Hunga Ha’apai Volcano on 15 January 2022. Geophysical Research Letters, 2024; 51 (21) DOI: 10.1029/2024GL111144

Note: The above post is reprinted from materials provided by American Geophysical Union.

What’s Inside Meteorites?

An example of a Pallasite meteorite (from the Esquel fall) on display in the Vale Inco Limited Gallery of Minerals at the Royal Ontario Museum. Credit: Captmondo
An example of a Pallasite meteorite (from the Esquel fall) on display in the Vale Inco Limited Gallery of Minerals at the Royal Ontario Museum. Credit: Captmondo

What’s Inside Meteorites? Exploring the Cosmic Composition

Meteorites are cosmic messengers, carrying clues about the formation of the solar system, planetary processes, and even the origins of life. These extraterrestrial fragments, which survive their fiery journey through Earth’s atmosphere, are scientifically invaluable due to their pristine preservation of ancient material. This article delves into the fascinating world of meteorites, revealing their compositions, structures, and the insights they provide into the cosmos.

Introduction to Meteorites

Meteorites are pieces of debris from celestial bodies like asteroids, comets, or planets that survive the descent through Earth’s atmosphere and land on its surface. They are classified into three primary categories based on their composition:

  1. Stony Meteorites (Chondrites and Achondrites): These are the most common, making up about 94% of all known meteorites.
  2. Iron Meteorites: Composed predominantly of iron and nickel alloys, they originate from the cores of differentiated planetary bodies.
  3. Stony-Iron Meteorites: A rare blend of metal and silicate minerals, these meteorites offer a glimpse into the interface between core and mantle regions of planetesimals.

How Are Meteorites Formed?

Meteorites are fragments of larger celestial bodies ejected by high-energy collisions in space. These collisions may involve asteroids, comets, or proto-planetary bodies. Over millions of years, these fragments travel through space until gravitational interactions or orbital alignments direct them toward Earth.

Connection with Asteroids and Comets:

  • Asteroids: Many meteorites originate from asteroid belt objects, offering insights into primordial materials.
  • Comets: Cometary meteorites are rarer but provide information about volatile-rich regions of the solar system.

Types of Meteorites and Their Composition

Meteorites vary significantly in their composition and origin:

  • Chondrites:
    These stony meteorites contain small, spherical particles known as chondrules, formed from molten droplets in the early solar nebula. They also include calcium-aluminum-rich inclusions (CAIs), which are among the oldest materials in the solar system.
  • Achondrites:
    Unlike chondrites, these meteorites lack chondrules. They originate from differentiated parent bodies where melting and crystallization occurred.
  • Iron Meteorites:
    Composed mainly of iron and nickel, they often display a unique Widmanstätten pattern, a crystalline structure visible upon etching.
  • Stony-Iron Meteorites:
    These rare meteorites are a mix of metallic iron-nickel and silicate minerals, representing core-mantle boundaries of disrupted planetesimals.

Elemental and Mineralogical Composition

Meteorites contain a wide range of elements, including common terrestrial ones like silicon, oxygen, and iron, as well as rarer elements such as iridium, which is linked to the extinction event that ended the Cretaceous period.

Key Elements:

  • Iron and Nickel: Dominant in iron meteorites.
  • Magnesium and Silicon: Abundant in stony meteorites.
  • Iridium and Platinum: Found in trace amounts, these are significant in studying asteroid impacts.

Organic Compounds in Meteorites

Meteorites often harbor organic compounds, making them crucial for astrobiology. For instance, the Murchison meteorite contains amino acids, the building blocks of life. Complex molecules like PAHs (Polycyclic Aromatic Hydrocarbons) suggest that prebiotic chemistry might be widespread in the cosmos.

Isotopic Signatures and What They Reveal

Meteorites contain isotopic signatures that provide a timeline for the solar system. Radiometric dating techniques, such as uranium-lead or argon-argon dating, help determine the age of these space rocks, often placing them at over 4.5 billion years old.

Microscopic Structures in Meteorites

Advanced imaging techniques have uncovered intricate microscopic structures in meteorites:

  • Chondrules: Glassy spheres within chondrites.
  • CAIs: High-temperature inclusions.
  • Nanodiamonds: Microscopic diamonds formed under intense pressure.

FAQs

  1. What is the most common type of meteorite?
    Chondrites are the most common type, accounting for 85–90% of meteorite finds.
  2. What elements are unique to meteorites?
    Rare elements like iridium and platinum are often found in meteorites and are less common on Earth.
  3. Can meteorites contain water?
    Yes, some meteorites, particularly carbonaceous chondrites, contain hydrated minerals.
  4. How are meteorites analyzed?
    Techniques include spectroscopy, electron microscopy, and isotope ratio mass spectrometry.
  5. What can meteorites tell us about asteroids?
    Meteorites provide direct samples from asteroids, revealing their composition and history.
  6. Are meteorites linked to the origins of life?
    Yes, they contain organic molecules like amino acids, which are essential for life.

Weather-changing El Nino oscillation is at least 250 million years old

The August 2023 El Nino, as mapped from space. The huge mass of warm water against the coast of Ecuador and Peru exerts global influence on weather patterns. (Image: NOAA)
The August 2023 El Nino, as mapped from space. The huge mass of warm water against the coast of Ecuador and Peru exerts global influence on weather patterns. (Image: NOAA)

The El Niño event, a huge blob of warm ocean water in the tropical Pacific Ocean that can change rainfall patterns around the globe, isn’t just a modern phenomenon.

A new modeling study from a pair of Duke University researchers and their colleagues shows that the oscillation between El Niño and its cold counterpart, La Niña, was present at least 250 million years in the past, and was often of greater magnitude than the oscillations we see today.

These temperature swings were more intense in the past, and the oscillation occurred even when the continents were in different places than they are now, according to the study, which appears the week of Oct. 21 in the Proceedings of the National Academy of Sciences.

“In each experiment, we see active El Niño Southern Oscillation, and it’s almost all stronger than what we have now, some way stronger, some slightly stronger,” said Shineng Hu, an assistant professor of climate dynamics in Duke University’s Nicholas School of the Environment.

Climate scientists study El Niño, a giant patch of unusually warm water on either side of the equator in the eastern Pacific Ocean, because it can alter the jet stream, drying out the U.S. northwest while soaking the southwest with unusual rains. Its counterpart, the cool blob La Niña, can push the jet stream north, drying out the southwestern U.S., while also causing drought in East Africa and making the monsoon season of South Asia more intense.

The researchers used the same climate modeling tool used by the Intergovernmental Panel on Climate Change (IPCC) to try to project climate change into the future, except they ran it backwards to see the deep past.

The simulation is so computationally intense that the researchers couldn’t model each year continuously from 250 million years ago. Instead they did 10-million-year ‘slices’ — 26 of them.

“The model experiments were influenced by different boundary conditions, like different land-sea distribution (with the continents in different places), different solar radiation, different CO2,” Hu said. Each simulation ran for thousands of model years for robust results and took months to complete.

“At times in the past, the solar radiation reaching Earth was about 2% lower than it is today, but the planet-warming CO2 was much more abundant, making the atmosphere and oceans way warmer than present, Hu said.” In the Mezozoic period, 250 million years ago, South America was the middle part of the supercontinent Pangea, and the oscillation occurred in the Panthalassic Ocean to its west.

The study shows that the two most important variables in the magnitude of the oscillation historically appear to be the thermal structure of the ocean and “atmospheric noise” of ocean surface winds.

Previous studies have focused on ocean temperatures mostly, but paid less attention to the surface winds that seem so important in this study, Hu said. “So part of the point of our study is that, besides ocean thermal structure, we need to pay attention to atmospheric noise as well and to understand how those winds are going to change.”

Hu likens the oscillation to a pendulum. “Atmospheric noise — the winds — can act just like a random kick to this pendulum,” Hu said. “We found both factors to be important when we want to understand why the El Niño was way stronger than what we have now.”

“If we want to have a more reliable future projection, we need to understand past climates first,” Hu said.

This work was supported by the National Natural Science Foundation of China (42488201) and the Swedish Research Council Vetenskapsrådet (2022-03617). Simulations were conducted at the High-performance Computing Platform of Peking University.

Reference:
Xiang Li, Shineng Hu, Yongyun Hu, Wenju Cai, Yishuai Jin, Zhengyao Lu, Jiaqi Guo, Jiawenjing Lan, Qifan Lin, Shuai Yuan, Jian Zhang, Qiang Wei, Yonggang Liu, Jun Yang, Ji Nie. Persistently active El Niño–Southern Oscillation since the Mesozoic. Proceedings of the National Academy of Sciences, 2024; 121 (45) DOI: 10.1073/pnas.2404758121

Note: The above post is reprinted from materials provided by Duke University. Original written by Karl Leif Bates

What happened when a meteorite the size of four Mount Everests hit Earth?

Mount Everest officially stands at 8,848 metres (29,029 feet) above sea level
Mount Everest officially stands at 8,848 metres (29,029 feet) above sea level

Billions of years ago, long before anything resembling life as we know it existed, meteorites frequently pummeled the planet. One such space rock crashed down about 3.26 billion years ago, and even today, it’s revealing secrets about Earth’s past.

Nadja Drabon, an early-Earth geologist and assistant professor in the Department of Earth and Planetary Sciences, is insatiably curious about what our planet was like during ancient eons rife with meteoritic bombardment, when only single-celled bacteria and archaea reigned — and when it all started to change. When did the first oceans appear? What about continents? Plate tectonics? How did all those violent impacts affect the evolution of life?

A new study in Proceedings of the National Academy of Sciences sheds light on some of these questions, in relation to the inauspiciously named “S2” meteoritic impact of over 3 billion years ago, and for which geological evidence is found in the Barberton Greenstone belt of South Africa today. Through the painstaking work of collecting and examining rock samples centimeters apart and analyzing the sedimentology, geochemistry, and carbon isotope compositions they leave behind, Drabon’s team paints the most compelling picture to date of what happened the day a meteorite the size of four Mount Everests paid Earth a visit.

“Picture yourself standing off the coast of Cape Cod, in a shelf of shallow water. It’s a low-energy environment, without strong currents. Then all of a sudden, you have a giant tsunami, sweeping by and ripping up the sea floor,” said Drabon.

The S2 meteorite, estimated to have been up to 200 times larger than the one that killed the dinosaurs, triggered a tsunami that mixed up the ocean and flushed debris from the land into coastal areas. Heat from the impact caused the topmost layer of the ocean to boil off, while also heating the atmosphere. A thick cloud of dust blanketed everything, shutting down any photosynthetic activity taking place.

But bacteria are hardy, and following impact, according to the team’s analysis, bacterial life bounced back quickly. With this came sharp spikes in populations of unicellular organisms that feed off the elements phosphorus and iron. Iron was likely stirred up from the deep ocean into shallow waters by the aforementioned tsunami, and phosphorus was delivered to Earth by the meteorite itself and from an increase of weathering and erosion on land.

Drabon’s analysis shows that iron-metabolizing bacteria would thus have flourished in the immediate aftermath of the impact. This shift toward iron-favoring bacteria, however short-lived, is a key puzzle piece depicting early life on Earth. According to Drabon’s study, meteorite impact events — while reputed to kill everything in their wake (including, 66 million years ago, the dinosaurs) — carried a silver lining for life.

“We think of impact events as being disastrous for life,” Drabon said. “But what this study is highlighting is that these impacts would have had benefits to life, especially early on … these impacts might have actually allowed life to flourish.”

These results are drawn from the backbreaking work of geologists like Drabon and her students, hiking into mountain passes that contain the sedimentary evidence of early sprays of rock that embedded themselves into the ground and became preserved over time in the Earth’s crust. Chemical signatures hidden in thin layers rock help Drabon and her students piece together evidence of tsunamis and other cataclysmic events.

The Barberton Greenstone Belt in South Africa, where Drabon concentrates most of her current work, contains evidence of at least eight impact events including the S2. She and her team plan to study the area further to probe even deeper into Earth and its meteorite-enabled history.

Reference:
Nadja Drabon, Andrew H. Knoll, Donald R. Lowe, Stefano M. Bernasconi, Alec R. Brenner, David A. Mucciarone. Effect of a giant meteorite impact on Paleoarchean surface environments and life. Proceedings of the National Academy of Sciences, 2024; 121 (44) DOI: 10.1073/pnas.2408721121

Note: The above post is reprinted from materials provided by Harvard University. Original written by Anne J. Manning.

Newly discovered Late Cretaceous birds may have carried heavy prey like extant raptors

Reconstruction of an avisaurid (e.g., A. darwini). Morphology of the tarsometatarsus suggests that these large birds engaged in raptorial behavior and could carry proportionally large prey. Illustration done by Ville Sinkkonen.Credit Clark et al., 2024, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
Reconstruction of an avisaurid (e.g., A. darwini). Morphology of the tarsometatarsus suggests that these large birds engaged in raptorial behavior and could carry proportionally large prey. Illustration done by Ville Sinkkonen.
Credit
Clark et al., 2024, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Newly discovered birds from Late Cretaceous North America were hawk-sized and had powerful raptor-like feet, according to a study published October 9, 2024 in the open-access journal PLOS ONE by Alexander Clark of the University of Chicago, U.S. and colleagues.

The most diverse birds during the Cretaceous Period were a now-extinct group called enantiornithines, known from all over the world during this time.

However, enantiornithines and other Mesozoic birds are mainly known from Lower Cretaceous deposits, with a relatively poor record from the Late Cretaceous.

Thus, there is a general lack of understanding of trends in bird evolution toward the end of the Mesozoic Era.

In this study, Clark and colleagues describe three new enantiornithine birds from fossils found in the Hell Creek Formation of Montana, dating to the latest Cretaceous Period (68 — 66 million years ago, shortly before the mass extinction that wiped out non-avian dinosaurs and enantiornithines). All three fossil birds are identified from lower leg bones.

Two are new species named Magnusavis ekalakaensis and Avisaurus darwini, while the third is an unnamed species of Avisaurus.

These birds are all larger than Early Cretaceous enantiornithines, with Avisaurus darwini estimated to have weighed over one kilogram, roughly the size of a large hawk.

Analysis of the leg bones of Avisaurus and its relatives reveals proportions and adaptations similar to hawks and owls, indicating powerful leg muscles and feet that could grip and potentially carry proportionally large prey, similar to some modern raptorial birds.

These fossils expand the known diversity of Late Cretaceous birds, confirm the trend toward large body size, and highlight how, over time, enantiornithines evolved a greater diversity of ecological roles.

This study emphasizes how even fragmentary fossils can reveal important ecological information and be used to clarify evolutionary trends.

The authors add: “Avisaurids, a group of enantiornithine birds from the latest Cretaceous, exhibit hindlimb features indicating strong ankle flexion, which suggests the ability to carry heavy prey and behaviors similar to living raptorial birds.”

Reference:
Alexander D. Clark, Jessie Atterholt, John B. Scannella, Nathan Carroll, Jingmai K. O’Connor. New enantiornithine diversity in the Hell Creek Formation and the functional morphology of the avisaurid tarsometatarsus. PLOS ONE, 2024; 19 (10): e0310686 DOI: 10.1371/journal.pone.0310686

Note: The above post is reprinted from materials provided by PLOS.

Understanding landslides: a new model for predicting motion

Paul's Slide, at Post Mile 22, has been active for much of the history of Highway 1 on the Big Sur coast. (Photos by Kevin Schmidt/USGS)
Paul’s Slide, at Post Mile 22, has been active for much of the history of Highway 1 on the Big Sur coast. (Photos by Kevin Schmidt/USGS)

Along coastal California, the possibility of earthquakes and landslides are commonly prefaced by the phrase, “not if, but when.” This precarious reality is now a bit more predictable thanks to researchers at UC Santa Cruz and The University of Texas at Austin, who found that conditions known to cause slip along fault lines deep underground also lead to landslides above.

The new study, led by UC Santa Cruz geologist Noah Finnegan, used detailed data from two landslide sites in Northern California that researchers have identified and closely monitored for years. Finnegan and his co-author then applied a model originally developed to explain slow fault slip and eventually landed on a striking result: The model worked just as well for landslides as it did for faults.

The finding is an important breakthrough suggesting that a model designed for faults can also be used to predict landslide behavior. And in California, where slow-moving slides are constant and cost hundreds of millions of dollars annually, this represents a major step forward in the ability to predict landslide movements — particularly in response to environmental factors like changes in groundwater levels.

According to Finnegan, landslides are essentially a “plumbing problem.” When rain saturates the ground, water pressure within rocks increases, and the friction that would otherwise work against slipping decreases, he explained.

“At a practical level, this study provides us with a framework for understanding how much motion to expect based on a change in rainfall, which leads to a change in water pressure in the ground that then translates into motion,” said Finnegan, a professor of earth and planetary sciences. “We have very few tools for thinking predictively, and this is an incremental step in that direction. It doesn’t solve the bigger problem, but it’s at least something that we can use now.”

In the world of earthquakes, especially in regions like California, one of the primary challenges is understanding the different behaviors of fault lines. Some faults are “locked” and only fail periodically, leading to large earthquakes. Others are constantly slipping, moving at a steady rate. Seismologists have spent decades trying to unravel why certain faults behave differently in order to better predict seismic activity and earthquake hazards.

Over the last two decades, researchers have begun to recognize that faults exhibit a wide range of slip behaviors. Some of these behaviors don’t produce noticeable earthquakes, but still influence fault mechanics. These quiet, “silent” slip events change the hazard landscape and present a puzzle because they are difficult to observe and understand.

Similarities between slides and quakes

Much like faults, landslides also behave differently. Some fail catastrophically, causing fatalities and widespread damage, while others creep slowly, causing chronic and cumulative infrastructure issues. A current example is the landslide in Rancho Palos Verdes, a city in northern L.A. County. There, the Portuguese Bend Landslide Complex has seen increased slippage over the last two years, resulting in utilities like gas and power being cut off to hundreds of homes due to safety concerns. Even though it’s a slow-moving landslide, the impact was still serious enough for Gov. Gavin Newsom to issue an emergency declaration.

“A fundamental question in landscape-hazards science is what controls the style of behavior. Why do some landslides creep and others fail rapidly and in a way that is much more destructive and hazardous?” said co-author Demian Saffer, director of the University of Texas Institute for Geophysics and a professor at UT Jackson School of Geosciences. “Landslide motion is analogous in many ways to tectonic faulting. If we can understand why some systems slip slowly and others fail catastrophically, it provides a window into the physics that control this style of behavior.”

Similar to the uncertainties in earthquake science, we have limited understanding of what controls the behavior of landslides — why some move slowly and steadily, while others fail suddenly. In earthquake science, friction’s effects are more clearly understood, particularly how friction changes as materials in the ground move. Scientists often distinguish between “static friction,” which keeps things at rest, and “dynamic friction,” which occurs when things are in motion. The challenge is that friction behaves differently under different conditions, and these changes are key to understanding how both earthquakes and landslides unfold.

For landslides, the study of friction is still in its early stages, but this paper presents a significant advance. The team found that friction affects faults and landslides in a similar fashion by using measurements of stress from instrumentation at the landslide sites, and tracking how fast they moved. They then compared this field data with friction experiments conducted in the lab. Specifically, they looked at how friction within the landslides changed with movement. The measurements from the field were found to align with the lab experiments, providing a consistent picture of how friction influences landslide motion.

Finnegan points to California’s iconic Highway 1 as a prime example of how insights from this study can have a positive, practical impact. “Caltrans is engaged in this constant battle to keep it open,” he said. “The benefit of this model lies in its ability to assist operational decisions on a more informed basis. It doesn’t just isolate data points but contextualizes them, enabling authorities to predict how changes in factors like rainfall can influence ground movement.”

Importance of material properties

A key part of the research focused on different types of rock and how their behavior under stress varies. For instance, clay-rich rocks tend to creep slowly and stably, while quartz-rich rocks are more likely to experience a sudden drop in friction when they start to slide, leading to catastrophic failure. This understanding could eventually allow scientists to predict how a landslide will behave based on the types of rock present in an area.

The researchers used field observations from two sites in Northern California. One is located just east of Fremont, which Finnegan first identified and has monitored for eight years. The other is in Humboldt County, far to the north, where observations were made by different scientists in the eighties. Both sites lie within the “Franciscan Melange,” a rock formation that is prone to slow-moving landslides. This formation is the remnant of an ancient subduction zone, where one tectonic plate slid beneath another, similar to what is happening today in the Cascadia region of Northern California.

According to Saffer, a key insight came when they connected field observations at the two sites with the kinds of data generated in rock-deformation experiments in the lab. They found that by thinking of the landslide itself as a large-scale “experiment,” the slides’ motion encoded clues about the material’s physics.

“It’s basically a giant rheology (rock deformation) experiment,” he said. “And it suggests that if we were to sample rocks in a region and take the reverse approach — by making detailed measurements of the rheology in the laboratory — we could in theory identify places where catastrophic rapid landslides are more likely and places where we expect the land to creep. That’s where we want to take this work next.”

Unlocking tectonic insights

One of the more abstract, but equally important, implications of this study is its relevance to plate tectonics and subduction zones. The rocks involved in the landslides being studied at one point existed at the interface of an ancient subduction zone, a setting that is notorious for producing devastating magnitude-9 earthquakes. These earthquakes are among the most destructive natural disasters on Earth.

Studying slow landslides in these types of rocks could offer valuable insights into the mechanics of slip processes in subduction zones. Due to the difficulty of taking direct measurements in these deep underwater fault environments, landslide research could illuminate how these plate interfaces behave under various conditions. In particular, understanding slip behavior in the fault zones at the seafloor could enhance predictions related to earthquake-triggered tsunamis, helping experts understand how and when these critical seismic events might occur.

“Apart from the practical value of this work, it’s also an example of how crossing disciplinary boundaries provides news insights on old problems,” Finnegan said. “In this case, we show how landslides — where it is relatively easy to make measurements — can provide a window into processes acting deep within faults, where measurements are nearly impossible but physical constraints are crucial for understanding hazards.”

Reference:
Noah J. Finnegan, Demian M. Saffer. Seasonal slow slip in landslides as a window into the frictional rheology of creeping shear zones. Science Advances, 2024; 10 (42) DOI: 10.1126/sciadv.adq9399

Note: The above post is reprinted from materials provided by University of California – Santa Cruz. Original written by Mike Peña

Iron nuggets in the Pinnacles unlock secrets of ancient and future climates

The Pinnacles Desert
The Pinnacles are limestone formations within Nambung National Park, near the town of Cervantes, Western Australia.

Small iron-rich formations found within Western Australia’s Pinnacles, which are part of the world’s largest wind-blown limestone belt spanning more than 1000km, have provided new insights into Earth’s ancient climate and changing landscape.

The new research found the pinnacles were formed about 100,000 years ago during what was the wettest period in the past half-million years for the area, and very different from the Mediterranean climate Western Australia experiences today.

Lead author Dr Matej Lipar, Adjunct Research Fellow in Curtin’s School of Earth and Planetary Sciences, now at the Research Centre of the Slovenian Academy of Sciences and Arts (ZRC SAZU), said the spectacular finger-like stone pinnacles at Nambung National Park are a type of karst created by water dissolving rocks.

“These formations offer crucial insights into ancient climates and environments, but accurately dating them has been extremely challenging until now,” Dr Lipar said.

“Karst landscapes, like those in Nambung National Park, are found globally and serve as sensitive indicators of environmental change. Studying them within an accurate timeline helps us understand how Earth’s geological systems respond to climate shifts.

“We found tyhis period was locally the wettest in the past half-million years, distinct from other regions in Australia and far removed from Western Australia’s current Mediterranean climate.

“An abundance of water during this time caused the limestone to dissolve, forming the distinctive pillars of the Pinnacles and creating the ideal environment for the iron nodules to develop.”

Curtin co-author Associate Professor Martin Danišík, from the John de Laeter Centre, said the iron-rich nodules acted as geological clocks, trapping helium from the consistent radioactive decay of tiny quantities of naturally occurring uranium and thorium.

“Measuring this helium provides a precise record of when the nodules formed,” Dr Danišík said.

“The innovative dating techniques developed in this study reveal the nodules date back about one hundred thousand years, highlighting an exceptionally wet climate period.”

Study co-author Associate Professor Milo Barham, from Curtin’s Timescales of Mineral Systems Group in the School of Earth and Planetary Sciences, said being able to reconstruct past climate changes was important given the context it provides to understanding human evolution and ecosystems more broadly amid dramatic climate fluctuations over the past three million years.

“This new knowledge will enhance our understanding of global environments and ecosystems, helping us prepare for, and mitigate the impacts of, a warming planet,” Dr Barham said.

“This research not only advances scientific knowledge but also offers practical insights into climate history and environmental change, relevant to anyone concerned about our planet’s present and future.”

An international collaboration with ZRC SAZU, the research project was supported by the Slovenian Research and Innovation Agency.

Reference:
Matej Lipar, Milo Barham, Martin Danišík, Andrej Šmuc, John A. Webb, Kenneth J. McNamara, Aleš Šoster, Mateja Ferk. Ironing out complexities in karst chronology: (U-Th)/He ferricrete ages reveal wet MIS 5c. Science Advances, 2024; 10 (40) DOI: 10.1126/sciadv.adp0414

Note: The above post is reprinted from materials provided by Curtin University. Original written by Lucien Wilkinson.

Tongan volcanic eruption triggered by explosion as big as ‘five underground nuclear bombs’

Sakurajima Volcano with LightningCredit & Copyright: Martin Rietze (Alien Landscapes on Planet Earth)
Sakurajima Volcano with Lightning
Credit & Copyright: Martin Rietze (Alien Landscapes on Planet Earth)

The Hunga Tonga underwater volcano was one of the largest volcanic eruptions in history, and now, two years later, new research from The Australian National University (ANU) has revealed its main trigger.

Until now, the cause of the cataclysmic event has remained largely a mystery to the scientific community, yet a student-led team of ANU seismologists has been able to shed new light on the natural explosion that initiated the event.

The student researchers analysed the climactic event’s noisy but valuable seismic records to decipher its mysterious physical mechanism.

“Our findings confirm there was an explosion, possibly due to a gas-compressed rock, which released energy that equated to five of the largest underground nuclear explosions conducted by North Korea in 2017,” study co-author and ANU PhD student, Jinyin Hu, said.

“Our model suggests the event resulted from the gas-compressed rock being trapped underneath a shallow sea, like an overcooked pressure cooker.

“This would be surprising to many because it had been commonly thought that the interaction of hot magma with cold seawater caused such massive underwater volcanic eruptions.

“We used a technique previously developed to study underground explosions for this natural explosion.”

Study co-author, Dr Thanh-Son Pham, said the explosion caused a massive vertical push of water upwards into the atmosphere, causing tsunamis that reached as high as 45 metres at nearby islands.

“The water volume that was uplifted during the event was huge. Based on our estimates, there was enough water to fill about one million standard Olympic-sized swimming pools,” Dr Phạm said.

Study co-author, Professor Hrvoje Tkalčić, from ANU, added: “Using seismic waveform modelling, we observed a significant vertical force pointing upward during the event. At first, we were confused by it. But then we realised that the solid earth rebounded upwards after the water column got uplifted,” he said.

“A couple of weeks ago, we saw how seismology was used to explain an extraordinary sequence of events in Greenland that included a landslide due to glacial melting, a tsunami, and a seiche lasting for nine days observed globally.

“With Hunga Tonga, we have a relatively short-duration explosive event observed globally and, again, academically driven curiosity and forensic seismology at its best.”

According to the ANU seismologists, the Tonga eruption is the best instrumentally recorded event compared to events of similar sizes in the recent past.

“This is one of the largest events in our lifetime. Luckily, we had multiple ways to record the event, from data from satellite images to seismic sensors that record the sound waves and structure,” Mr Hu said.

“There was another event that happened in 1991 that was a similar size in Pinatubo in the Philippines, but back then, monitoring systems weren’t as sophisticated as they are now.”

The ANU seismologists believe that monitoring the release of gases and micro-seismicity from volcanic sites can help better prepare for future events.

Reference:
Jinyin Hu, Thanh‐Son Phạm, Hrvoje Tkalčić. A Composite Seismic Source Model for the First Major Event During the 2022 Hunga (Tonga) Volcanic Eruption. Geophysical Research Letters, 2024; 51 (18) DOI: 10.1029/2024GL109442

Note: The above post is reprinted from materials provided by Australian National University.

Closer look at New Jersey earthquake rupture could explain shaking reports

Photo of Taylor’s Mill in Readington Township, New Jersey after the 5 April 2024 earthquake. | GEER-NIST
Photo of Taylor’s Mill in Readington Township, New Jersey after the 5 April 2024 earthquake. | GEER-NIST

The magnitude 4.8 Tewksbury earthquake surprised millions of people on the U.S. East Coast who felt the shaking from this largest instrumentally recorded earthquake in New Jersey since 1900.

But researchers noted something else unusual about the earthquake: why did so many people 40 miles away in New York City report strong shaking, while damage near the earthquake’s epicenter appeared minimal?

In a paper published in The Seismic Record, YoungHee Kim of Seoul National University and colleagues show how the earthquake’s rupture direction may have affected who felt the strongest shaking on 5 April.

Kim and her colleague and co-author Won-Young Kim of Lamont-Doherty Earth Observatory of Columbia University became curious about the strange pattern of shaking after visiting the epicenter area of the earthquake just eight hours after the mainshock.

“We expected some property damages — chimneys knocked down, walls cracked or plasters fallen to the ground — but there were no obvious signs of property damages,” the researchers said in an email. “Police officers within a couple of kilometers from the reported epicenter calmly talked about the shaking from the mainshock. It was a surprising response by the people and houses for a magnitude 4.8 earthquake in the region.”

“This contrasted with the wide and huge response from the residents in and around the New York City area, some 65 kilometers from the epicenter,” they added.

The earthquake garnered more than 180,000 felt reports — the largest number ever for a single earthquake received by the U.S. Geological Survey’s “Did You Feel It?” app and website, according to a second paper published in The Seismic Record by USGS seismologist Oliver Boyd and colleagues.

Boyd and colleagues said the earthquake was felt by an estimated 42 million people between Virginia and Maine.

The reports from people southwest of the epicenter, toward Washington, D.C., indicated “weak” shaking on the scale that the USGS uses to measure an earthquake’s intensity, while people reporting from northeast of the epicenter felt “light to moderate” shaking.

Based on previous models of magnitude and earthquake intensity developed for the eastern U.S., however, a magnitude 4.8 earthquake should produce very strong shaking within about 10 kilometers or about six miles from its epicenter.

With this pattern in mind, Kim and colleagues wanted to look closer at the directivity of the earthquake’s rupture. To model the rupture, they turned to a kind of seismic wave called Lg waves, due to the lack of nearby seismic observation at the time of the mainshock. Lg waves are shear waves that bounce back and forth within the crust between the Earth’s surface and the boundary between the crust and mantle.

The resulting model indicated the earthquake rupture had propagated toward the east-northeast and down on an east-dipping fault plane. The direction of the rupture might have funneled the earthquake’s shaking away from its epicenter and toward the northeast, the researchers concluded.

In general, earthquakes in the northeastern U.S. take place as thrust faulting along north-south trending faults. The New Jersey earthquake is unusual, Kim and colleagues noted, because it appears to have been a combination of a thrust and strike-slip mechanism along a possible north-northeast trending fault plane.

“Earthquakes in the eastern North America usually occur along the pre-existing zone of weakness — that is, existing faults,” the researchers explained. “In the Tewksbury area, a hidden fault plane trending north-northeast and dipping moderately can be mapped from the numerous small aftershocks detected and located” after the Tewksbury mainshock.

Boyd and colleagues noted that some damage was documented by a reconnaissance team deployed by the Geotechnical Extreme Events Reconnaissance Association and the National Institute of Standards and Technology. Along with cracks in drywall and objects falling from shelves, the team documented the partial collapse of the stone façade of Taylor’s Mill, a pre-Revolutionary War structure near the town of Lebanon, New Jersey.

The researchers have not yet attributed the earthquake to a particular fault but the locations of the mainshock and aftershocks suggest that the area’s well-known Ramapo fault system was not active during the earthquake.

The findings could “help us identify new earthquake sources and rethink how stress and strain are being accommodated in the eastern United States,” Boyd said.

He noted that some seismometers that were rapidly deployed to the region by the USGS will remain in place for at least five months.

“This can help us study, for example, mechanisms related to how the crust responds to the stress of a mainshock in the region, and how productive aftershock sequences can be in the eastern United States,” Boyd explained.

“Good station coverage can also allow us to observe how earthquake ground motions vary across the region as a function of magnitude, epicentral distance, and Earth structure. And each of these examples can help us better appreciate potential seismic hazards.”

Reference:
Sangwoo Han, Won-Young Kim, Jun Yong Park, Min-Seong Seo, YoungHee Kim. Rupture Model of the 5 April 2024 Tewksbury, New Jersey, Earthquake Based on Regional Lg-Wave Data. The Seismic Record, 2024; 4 (3): 214 DOI: 10.1785/0320240020

Note: The above post is reprinted from materials provided by Seismological Society of America.

Mystery of Uruguay’s amethyst geodes

Amethyst-calcite geode from Los Catalanes already processed in the workshop and ready to sell.Photo: Fiorella Arduin Rode
Amethyst-calcite geode from Los Catalanes already processed in the workshop and ready to sell.
Photo: Fiorella Arduin Rode

Amethyst is a violet variety of quartz which has been used as a gemstone for many centuries and is a key economic resource in northern Uruguay. Geodes are hollow rock formations often with quartz crystals, such as amethyst, inside. Amethyst geodes in Uruguay have been found in cooled lava flows, which date from the original breakup of the supercontinent Gondwana around 134 million years ago. However, their formation has remained a mystery. So, a research team led by the University of Göttingen investigated using cutting-edge techniques. The researchers discovered that the amethyst geodes formed at unexpectedly low crystallisation temperatures of just 15 to 60 °C. Taken with their other results, researchers were able to propose a new model to explain their formation. The research was published in the journal Mineralium Deposita.

Amethyst has been mined for over 150 years in the Los Catalanes District of Uruguay, where the research was carried out.

This is an area renowned for the deep violet colour and high quality of its gems, as well as magnificent giant geodes sometimes over 5 m high.

The deposits here have been recognised as one of the top 100 geological heritage sites in the world, highlighting their scientific and natural value.

However, limited knowledge of how these geodes formed has made locating them challenging, relying largely on miners’ experience.

To address this, researchers conducted extensive geological surveys across more than 30 active mines, analysing geode minerals, geode-hosted water, and groundwater.

Using advanced techniques like nucleation-assisted microthermometry of initial one-phase fluid inclusion and triple-oxygen-isotope geochemistry, the team uncovered new insights into how these prized geodes formed.

As well as finding that the amethyst geodes formed at unexpectedly low crystallisation temperatures, the researchers also showed that the mineralising fluids had the low levels of salinity and proportion of isotopes consistent with water originating from the natural weather cycle, which probably came from groundwater held in nearby rocks.

“The precision and accuracy of these new techniques, allowed us to estimate with confidence the temperature and composition of the mineralizing fluids,” said Fiorella Arduin Rode, lead author and PhD researcher at Göttingen University’s Geoscience Centre.

“Our findings support the idea that these amethysts crystallised at low temperatures from groundwater-like fluids.” The study proposes a model where mineral phases like amethyst crystallise within volcanic cavities in a dark rock known as basalt, influenced by regional variations in temperature in the Earth’s crust.

Arduin Rode adds, “Understanding the conditions for amethyst formation — such as the temperature and composition of the mineralising fluid, as well as the silica source, the timing of the mineralisation, and its relationship with the host rocks — is crucial for unravelling the process. This could significantly improve exploration techniques and lead to sustainable mining strategies in the future.”

Funding for this research was provided by Research Grants — Doctoral Programmes in Germany, 2021/22 — 57552340 — Deutscher Akademischer Austauschdienst (DAAD)

Reference:

Fiorella Arduin-Rode, Graciela Sosa, Alfons van den Kerkhof, Yves Krüger, David Bajnai, Andreas Pack, Tommaso Di Rocco, Pedro Oyhantçabal, Klaus Wemmer, Daniel Herwartz, Swea Klipsch, Bettina Wiegand, Siegfried Siegesmund, Mathias Hueck. World-class amethyst-agate geodes from Los Catalanes, Northern Uruguay: genetic implications from fluid inclusions and stable isotopes. Mineralium Deposita, 2024; DOI: 10.1007/s00126-024-01310-2

Note: The above post is reprinted from materials provided by University of Göttingen.

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