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Giant Ancient Blobs in Earth’s Mantle Could Be Over a Billion Years Old

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Massive continent-sized structures buried deep within Earth’s mantle may be more than a billion years old, shedding new light on the planet’s internal dynamics. Known as large low-seismic-velocity provinces (LLSVPs), these formations are distinct from the surrounding mantle due to their unique physical and chemical properties. Located at the boundary between the mantle and the outer core, roughly 3,000 kilometers beneath the surface, these enigmatic structures have intrigued scientists for decades. Their ability to slow down seismic waves suggests they are compositionally different, possibly containing denser or hotter materials than the rest of the mantle.

A recent study published in Nature analyzed seismic data from over 100 significant earthquakes to investigate these deep-mantle structures. As reported by Space.com, Utrecht University seismologist Arwen Deuss explained that while it was well known that seismic waves slow down in these regions, an unexpected finding was that the waves also lose less energy than anticipated. This suggests that temperature alone cannot account for the properties of LLSVPs, indicating that other factors—such as mineral composition or internal structure—play a role in their formation and persistence over geological time.

One of the key insights from the study is the role of crystal size in influencing how seismic waves behave within LLSVPs. Computer simulations suggest that seismic energy is affected by the grain boundaries between crystals, with smaller crystals leading to greater energy loss and larger crystals allowing waves to pass with less resistance. Deuss noted that while the surrounding mantle consists of fragmented tectonic plates that have broken down over time, the LLSVPs appear to have remained relatively undisturbed, preserving their larger crystal structures for over a billion years.

These findings offer a new perspective on the deep interior of Earth and its geological evolution. Understanding LLSVPs is crucial for unraveling the processes that shape mantle convection, plate tectonics, and even volcanic activity at the surface. Further research into these massive formations could help explain the role they have played in Earth’s history, including their potential connection to supercontinent cycles and deep-mantle plumes that drive hotspot volcanism.

Earthquake Swarm Near Santorini Prompts Emergency Action from Greek Authorities

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Greek authorities have launched an emergency response to a growing earthquake swarm near Santorini, triggering the closure of schools and the deployment of emergency teams across the region. The tremors, which began last week, have steadily increased in frequency and strength, prompting fears of potentially more powerful earthquakes. The largest tremor recorded so far reached a magnitude of 5, striking around 34 kilometers northeast of Santorini at 2:27 p.m. local time, as reported by the University of Athens’ earthquake monitoring system. While the situation remains unpredictable, experts have ruled out an immediate volcanic eruption despite the heightened seismic activity.

Experts attribute the ongoing tremors to fault movement rather than volcanic unrest. Santorini, located on the tectonic boundary between the African and Eurasian plates, sits atop the submerged Santorini caldera, which has previously been a site of volcanic activity. According to David Pyle, a professor of Earth Sciences at the University of Oxford, the current swarm is more likely the result of tectonic fault lines shifting, rather than magma-related activity. He noted that the swarm’s underwater location adds complexity to predicting future seismic events, making it difficult to fully assess the potential risks.

The region’s geological activity is driven by the tectonic interaction between the African and Eurasian plates, which causes significant seismic events. Earthquake swarms are not uncommon in the area; however, this recent series is particularly notable for its intensity and location. A similar swarm was recorded between 2011 and 2012, which was linked to magma movement beneath Santorini. This current event, however, appears to be more expansive, with tremors concentrated mainly between the Kolumbo volcano and Anydros Island, both of which are located underwater.

As authorities continue to monitor the situation closely, the unpredictable nature of the swarm underscores the challenge of forecasting seismic activity in a region with such complex tectonic dynamics. While there is currently no immediate volcanic threat, the authorities remain on high alert, prepared to respond to any further developments as they occur.

Gold-Sulfur Complex Identified as Key Factor in Gold Deposit Formation

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Gold-Sulfur Complex Found to Play Crucial Role in Gold Deposit Formation

An international team of scientists has made a groundbreaking discovery that could transform our understanding of gold deposit formation on Earth. Led by Adam Simon, Professor of Earth and Environmental Sciences at the University of Michigan, the study uncovers the crucial role of a gold-sulfur complex in transporting gold from deep within the Earth’s mantle to the surface. The findings, published in Proceedings of the National Academy of Sciences (2024), offer new insights into the conditions under which gold is mobilized and concentrated in Earth’s crust.

The Gold-Trisulfur Complex: A Key to Gold’s Journey

According to the study, gold is transported in the Earth’s mantle in a complex form known as the gold-trisulfur complex. This complex forms under specific temperature and pressure conditions, typically located 30 to 50 miles beneath active volcanic zones. For years, the existence of such a complex was debated, but this research has solidified its role in enriching magma with gold as it rises towards the surface. The discovery also helps explain why certain areas, particularly subduction zones, are particularly rich in gold deposits.

Subduction Zones and Volcanic Activity as Gold Sources

The researchers specifically highlight subduction zones, such as those around the Pacific Ring of Fire, as key regions for gold formation. These areas, known for their high volcanic activity, provide an ideal geological environment for gold to be carried from the mantle to surface deposits through volcanic eruptions. Locations such as New Zealand, Japan, Alaska, and Chile, which lie within these active volcanic regions, are some of the richest in gold, thanks to the unique geological processes at play in subduction zones. The study links volcanic eruptions to the mechanisms that concentrate gold in these zones, shedding light on how gold deposits form in these high-activity areas.

Implications for Gold Mining and Exploration

This new understanding of how gold is transported from deep within the Earth to surface deposits opens up new avenues for gold exploration and mining. By targeting subduction zones with the right conditions for the formation of gold-sulfur complexes, geologists and mining companies can potentially uncover new gold reserves in regions that were previously unexplored. This discovery not only improves our knowledge of the Earth’s processes but also enhances the accuracy and efficiency of gold prospecting in volcanic regions around the world.