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Publication date: 15 October 2025

Source: Advances in Space Research, Volume 76, Issue 8

Author(s): YeonJeong Jeong, Vithurshan Suthakar, Randa Qashoa, Gunho Sohn, Regina S.K. Lee

By evaluating historical climate records, observational and projection data, an international team of researchers found a "pushing and triggering" mechanism that has driven the Arctic climate system to a new state, which will likely see consistently increased frequency and intensity of extreme events across all system components—the atmosphere, ocean and cryosphere—this century.

In some parts of Earth's interior, seismic waves travel at different speeds depending on the direction in which they are moving through the layers of rock in Earth's interior. This property is known as seismic anisotropy, and it can offer important information about how the silicate rock of the mantle—particularly at the mantle's lowermost depths—deforms. In contrast, areas through which seismic waves travel at the same speed regardless of direction are considered isotropic.

In a remote cave in northern Greenland, a research team led by geologists Gina Moseley, Gabriella Koltai, and Jonathan Baker from the University of Innsbruck has discovered evidence of a significantly warmer Arctic. The cave deposits show that the region was free of permafrost millions of years ago and responded sensitively to rising temperatures.

For much of the 20th century, “petroleum politics” shaped international policy. In the 21st century, a new set of resources has taken center stage: critical minerals. Sourcing and extracting these minerals have become a priority for countries and communities around the world because they are used in everything from solar panels to cell phones to superconductors.

A new study suggests where prospectors can search for critical minerals: rifting sites left behind by the supercontinent Rodinia, which broke up in the Proterozoic, more than 800 million years ago.

“To better find [critical] resources, really, we need a better understanding of geology.”

“Unless it is grown, absolutely everything on the planet that we use as a manufactured good requires something that comes out of a mine,” said Chris Kirkland, a geologist at Curtin University in Australia and a coauthor of the new study, published last month in Geological Magazine. “To better find those resources, really, we need a better understanding of geology.”

Kirkland and his colleagues began by analyzing rocks unearthed by drilling companies in Western Australia. The slabs contain carbonatite, a “weird,” rare, and poorly understood kind of igneous rock formed in the mantle from magmas rich in carbonate minerals. As the magmas rise through Earth’s interior, they react with surrounding rocks, altering the chemical signatures that geologists typically use to trace a sample’s origins.

Carbonatites often contain rare earth elements, such as niobium. Although niobium can be found in different rocks, carbonatites are the only ones offering it in amounts economically suitable for extraction. The Western Australia sites are home to more than 200 million metric tons of the metal.

The team “threw the whole kitchen sink of analytical techniques” at the carbonatites, explained Kirkland. The first step was to take a drill core sample and image its structure to see the broad geological ingredients inside. Then the researchers used lasers to sample individual grains and piece out their crystals.

The carbonatites contained zircon, apatite, and mica, all crystals with isotopes that decay at known rates and can tell researchers about the sample’s age and source. The researchers also analyzed the helium present in zircon, because helium is a volatile element that easily escapes rocks near the surface and can help reveal when the rocks reached the crust.

Written in Stone

The story written in the slabs is one tied to the long history of plate tectonics. The breakup of Rodinia began around 800 million years ago and continued for millions of years as hot, metal-enriched oozes of magma rose up from the mantle. Pressure from this rising rock helped split apart the supercontinent, and the metals encased in carbonatites breached the surface at once-stable mounds of continental crust called cratons.

Today, said Kirkland, tracking these “old fossil scars” where cratons split could reveal stores of minerals.

More than 200 million metric tons of niobium were recently identified in Australia’s Aileron Province, a likely result of the breakup of Rodinia. Credit: Dröllner et al., 2025, https://doi.org/10.1017/S0016756825100204

“Reconstructing a geologic history for one particular area on Earth is something that I think has potential to help us in better understanding these pretty poorly understood carbonatite systems globally,” said Montana State University geologist Zachary Murguía Burton, who was not involved with the paper.

Burton estimates that some 20% of the carbonatites on Earth contain economically attractive concentrations of critical minerals, although he noted that the rocks in the study experienced a unique confluence of local and regional geologic processes that might influence the minerals they contain.

In particular, the carbonatites analyzed in the new study identified the source of recently discovered niobium deposits beneath central Australia. Niobium is a critical mineral used in lithium-ion batteries and to strengthen and lighten steel. Because 90% of today’s supply of niobium comes from a single operation in Brazil, finding additional deposits is a priority.

In addition to niobium, Kirkland said a geologic “recipe” similar to the one his team identified might work for finding gold.

The work is an important reminder of “how tiny minerals and clever dating techniques can not only solve deep-time geological puzzles, but also help guide the hunt for the critical metals we need,” Kirkland said.

—Hannah Richter (@hannah-richter.bsky.social), Science Writer

Citation: Richter, H. (2025), To find critical minerals, look to plate tectonics, Eos, 106, https://doi.org/10.1029/2025EO250393. Published on 21 October 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Geochemistry, Geophysics, Geosystems

In some parts of Earth’s interior, seismic waves travel at different speeds depending on the direction in which they are moving through the layers of rock in Earth’s interior. This property is known as seismic anisotropy, and it can offer important information about how the silicate rock of the mantle—particularly at the mantle’s lowermost depths—deforms. In contrast, areas through which seismic waves travel at the same speed regardless of direction are considered isotropic.

In the bottom 300 kilometers of the mantle, also known as the D’’ layer, anisotropy is potentially caused by mantle plumes or mantle flow interacting with the edges of large low-shear-velocity provinces: continent-sized, dense, hot BLOBs (big lower-mantle basal structures) at the base of the mantle above the core. Many questions persist about the viscosity, movement, stability, and shape of the BLOBS, as well as about how they can be influenced by mantle plumes and subduction.

Roy et al. used ASPECT, a 3D mantle convection modeling software, and ECOMAN, a mantle fabric simulation code, to examine the deep mantle. They tested five different mantle model configurations, adjusting the viscosity and density of the BLOBs. The goal was to see which configuration would most closely re-create the observed seismic anisotropy.

The researchers treated the BLOBs as regions with their own unique chemistry, which form from a 100-kilometer-thick layer at the bottom of the mantle. Their models simulated how mantle plumes formed over the past 250 million years, during which time events such as the breakup of Pangaea, the opening of the Atlantic, and the evolution of various subduction zones occurred.

The study suggests that the best explanation for observed seismic anisotropy is when the BLOBs are 2% denser and 100 times more viscous than the surrounding mantle. This aligns with observations of anisotropy patterns in seismic data. Plumes form mainly at the edges of BLOBs, where strong deformation causes strong anisotropy. (Geochemistry, Geophysics, Geosystems, https://doi.org/10.1029/2025GC012510, 2025)

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Seismic anisotropy reveals deep-mantle dynamics, Eos, 106, https://doi.org/10.1029/2025EO250392. Published on 21 October 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

About 15% of Italy's energy is produced by its nearly 5,000 hydroelectric power plants. In the Valle dei Laghi region, water flowing from the surrounding mountains supports local agriculture and the Santa Massenza hydroelectric plant, which powers the entire Trentino province. But as climate change accelerates, this delicate equilibrium is shifting.

Scientists from The Australian National University (ANU) have analyzed signals generated by the vibrations of traffic along the Federal Highway to learn more about the seismic nature of Lake George, situated north-east of Canberra.

Once considered a fringe idea, the prospect of offsetting global warming by releasing massive quantities of sunlight-reflecting particles into Earth's atmosphere is now a matter of serious scientific consideration. Hundreds of studies have modeled how this form of solar geoengineering, known as stratospheric aerosol injection (SAI), might work.

Gully washer. Duck drownder. Toad strangler. Cob floater. Sod soaker. Whatever their names, summer in the Midwest isn't summer without strong, sudden storms with towering clouds. While the Indian subcontinent is famous for its monsoon season, what many people don't know is that the midwestern United States has its own monsoon season, very nearly as strong.

Author(s): Bhavesh Ramkorun, Saikat C. Thakur, Ryan B. Comes, and Edward Thomas, Jr.

Carbonaceous dusty nanoparticles spontaneously grow in nonthermal plasmas from a gas mixture of argon and acetylene. These particles levitate and grow within the bulk plasma for a duration known as the growth cycle (Tc), after which they gradually move away. In experiments operating at 500 milliTorr…

[Phys. Rev. E 112, 045211] Published Tue Oct 21, 2025

AbstractGeophysical measurements such as induced polarization (IP) are invaluable for understanding the physical properties of rocks, including pore structure, hydraulic properties, and mineral content. However, collecting reliable IP measurements from low-permeability rocks poses substantial challenges due to the difficulty of saturating their tight pore spaces. Additionally, IP measurements on rocks that are not cored to fit conventional sample holders, or are irregularly shaped, are particularly difficult to obtain. In this work, we address these challenges through (1) the use of reliable saturation procedures developed for low-permeability samples, and (2) a molding procedure designed to overcome the difficulties of measuring IP on irregularly shaped or broken rock cores. Core-scale gravimetric porosity measurements closely match values obtained from destructive mercury intrusion porosimetry (MICP) on rock fragments, confirming the effectiveness of the saturation procedure. Direct comparisons of IP measurements between molded and unmolded cores demonstrate that the molding process does not significantly alter the intrinsic electrical response of the samples. Fully saturated mudstones exhibit strong statistically significant relationships between the mean relaxation time (τmean) and permeability (k), and between effective porosity (1/formation factor, F) and interconnected porosity (ϕ) (Archie’s law). Conversely, partial saturation due to ineffective saturation methods introduces substantial scatter to these petrophysical correlations. Overall, these findings underscore the potential of these methods to enhance the reliability and accuracy of SIP measurements on challenging rock samples.

SummaryOn January 18, 2021, a blind mid-crustal Mw ∼6.4 earthquake occurred near San Juan, Argentina. The observation of associated ground deformation with single interferograms is obscured by strong tropospheric signals. We apply appropriate corrections to the data and reconstruct the deformation field associated to the event through InSAR time series approach. We show it is possible to retrieve this signal to invert the fault parameters. The observed ground deformation is consistent with a high angle NW-dipping fault plane at a centroid depth of ∼19 km. The geometry of this fault supports the reactivation of pre-existing structures within the Cuyania Terrane, suggesting a direct structural connection and strain transfer to the actively deforming, east-vergent Precordillera front. We analyze our findings to deduce a static friction coefficient ≤0.3 for mid-crustal faults of the region.

SummaryWe refined the Attenuated ProPagation of Local Earthquake Shaking (APPLES) ground-motion-based earthquake early warning (EEW) approach, and directly compare APPLES performance with that of the source-characterization-based U.S. ShakeAlert EEW system for a suite of historical earthquakes in the U.S. West Coast and Japan. APPLES is an extension of the Propagation of Local Undamped Motion (PLUM) algorithm in which observed shaking intensity at seismic stations is used to forward-predict intensity distributions to surrounding areas using an attenuation model derived from an intensity prediction equation. We test new configuration options within APPLES, such as using the second highest estimated ground motion rather than the maximum, to better match median ground-motion observations and reduce alerts for small magnitude earthquakes, both of which are key alerting priorities within ShakeAlert. We evaluate these configurations alongside ShakeAlert by comparing the ground-motion estimation accuracy and available warning times relative to station observations and ShakeMap distributions. Our preferred APPLES configuration produces accurate ground-motion estimates and corresponds better with median observations compared to ShakeAlert’s estimates. This preferred configuration substantially reduces alert issuance for M < 5.0 earthquakes compared to the previous APPLES configuration, and alert-release criteria can further restrict alerts to primarily M ≥ 5.5 earthquakes without requiring magnitude estimation. Prioritizing matching median-observed ground motions may reduce APPLES warning times compared to configurations that were tuned to avoid missed alerts (such as those that use the maximum estimated ground motions), which can lead to shorter warning times compared to ShakeAlert for the same alert threshold. However, station-based warning time assessments demonstrate that APPLES can outperform ShakeAlert for high target thresholds. APPLES is a simple, independent EEW approach that may improve the robustness of EEW for the West Coast of the U.S.

SummaryMetallic infrastructure, such as steel sheet situated within landfills, poses significant challenges to accurate tracking of leachate using induced polarization (IP) methods. The application of IP method is efficient to delineate leakage; however, the presence of metallic structures can cause an interference on the survey and generate high-chargeability anomalies as observed in field survey. To comprehensively validate the interference caused by steel sheets, both numerical and empirical field tests were conducted. As expected, both results demonstrate that interference diminishes as the distance between survey line and metallic structure increases. Additionally, at consistent intervals, the chargeability values inverted using integral chargeability (IC) exhibit a monotonic increase with depth. Moreover, the interference induced by metallic structures is also affected by the controlling factors (i.e. depth, width and thickness) of the structure alongside the intrinsic resistivity and chargeability. Strategic utilization of the size, chargeability, and spatial positioning of metallic structures relative to survey lines can significantly enhance background polarization. This approach offers a promising framework for improving the spatial resolution of subsurface targets exhibiting low polarization effects. The optimization of survey line placement, which must consider the dimensions and electrical properties of metallic structures such as steel sheets, is essential for accurately characterizing landfill leachate using the IP method.

SummaryNorthern Europe experiences vertical land motion and sea level changes that deviate from the average as a consequence of past changes in ice sheet cover in Fennoscandia and the British Isles. The process, called Glacial Isostatic Adjustment (GIA), is controlled by the subsurface structure. Numerical models of GIA can be compared to observations of uplift or past sea level changes to constrain the subsurface structure, and such models can also be used to correct present-day sea level observations to reveal sea level changes due to climate change. GIA models for northern Europe usually adopt a homogeneous upper mantle viscosity even though seismic studies indicate contrasting elastic lithosphere thickness and upper mantle structure between Northwestern Europe and Eastern Europe. This raises the question whether the effect of lateral variations in structure (3D viscosity) can be detected in observations of GIA and whether including such variations can improve GIA model predictions. In this study we compare model output from a finite element GIA model with 3D viscosity to observations of paleo sea level and current vertical land motion. We use two different methods to derive 3D viscosities, based on seismic velocity anomalies and upper mantle temperature estimates. We use three different reconstructions of the Eurasian ice sheet, one based on an inversion using a 1D model, and two others based on glacial geology and modelling. When we use these two reconstructions, we find that the data are fit better using 3D viscosity models. Models with two separate 1D viscosities for Fennoscandia and for the British Isles cannot replicate a 3D model because a 3D model redistributes GIA-induced stresses differently from a combination of models with separate 2D viscosities. The fit to data across Fennoscandia is improved when, as indicated by seismic models, the upper mantle viscosity is higher than for the rest of Northern Europe. The best fit is obtained with a model with dry olivine rheology, in agreement with other evidence from Fennoscandia.

SummaryIn both onshore and offshore seismic exploration, seismic source localization plays a crucial role in ensuring operational safety and environmental protection. With the continuous advancement of the Marchenko method in the fields of seismic migration and internal multiple elimination, this paper investigates a seismic source localization method based on the Marchenko method, aiming to further extend application domain of this method. The key to this method lies in the data reconstruction based on convolution operations. The conventional Marchenko method is then applied to obtain a seismic profile, which includes the location of the seismic source. In the experiments, this study first uses an anticline model to simulate seismic source localization in onshore seismic exploration. The results show that the proposed method can accurately estimate both the distance to the seismic source and its depth. Furthermore, in large-scale marine model experiments, the method is also able to reliably determine the distance between the seismic source and the observation stations.

SummaryFor the interpretation of Spectral Induced Polarization spectra, the determination of the Relaxation Time Distributions (RTD) can be useful, for instance to extract the grain size distribution. However, this is an ill-posed problem, and retrieving the RTD often requires regularization during the inversion process. In this note, we use Bézier curves and simulated annealing to determine the RTD. The procedure that does not require any regularization nor smoothing, by reducing the number of parameters thanks to Bézier curves which are intrinsically continuous and infinitely derivable. We successfully applied our methodology to three examples (Cole-Cole model, Davidson-Cole model, and an experimental spectrum), demonstrating its interest and efficiency.

SummaryThe extension of direct current resistivity methods to induced polarization methods has enriched the tools available for subsurface exploration. This enrichment involves an increase in the number of parameters used in the models, as well as addressing different physical phenomena than those observed with direct current. Accounting for non-linearities, if they exist, can further enhance the sophistication of our models. Non-linearities are often observed, particularly in laboratory experiments. However, we question their origin, and the experiment described here suggests that the non-linearities observed under typical experimental conditions may be artifacts related to the electrodes, rather than reflecting the actual response of the subsurface. Indeed, we first replaced the polarizable injection electrodes with non-polarizable electrodes. The non-linearities observed due to the presence of harmonics were significantly reduced. Then, we replaced the voltage control with a current control, which completely eliminated the non-linearities still present.We know that it is impossible to prove the non-existence of a phenomenon that does not exist. This fundamental epistemological principle (as pointed out by Russell and Popper) means that we are not claiming that nonlinearity does not exist. We are simply describing an experiment that can raise doubts about its existence.

For years, we believed the Himalayas were a climatic sanctuary—untouched, pristine, and resilient to the turbulence of modernization. But what happens when mountain cities begin to mimic the dynamics of megacities in the plains?