Solving The Dolomite Problem
The Dolomite Mountains in South Tirol.
The mineral Dolomite — a calcium-magnesium-carbonate — forms the dolostone landscape of the Dolomite mountains in Italy, the Niagara Escarpment between the U.S. and Canada, covers vast areas of the North American continent, the Iberian Peninsula, China, South Africa and is very abundant in marine sediments older than 100 million years with depositional thicknesses exceeding several hundred meters.
Yet scientists have failed to grow significant amounts of dolomite in the laboratory. Under Earth's surface temperature and pressure conditions chemical effects hinder the incorporation of magnesium ions into the crystal structure, favoring the formation of pure calcium carbonate like calcite or aragonite. This finding aligns with geological observations indicating the scarcity of dolomite in contemporary sediments.
This distinctive geological phenomenon, coupled with unsuccessful synthesis attempts, has given rise to the 'dolomite problem,' which has perplexed geologists for over two centuries.
Three primary hypotheses have been proposed regarding the mechanisms of dolomite genesis:
In 2023, a study using a combination of computer simulations and laboratory tests showed how repeated deposition of magnesium and calcium layers followed by dissolution of parts of the crystal, removing so the surplus calcium, can create stable dolomite near ambient conditions.
Dolomite crystals in dolostone from the Dolomites.
A new study published by Chinese researchers adds further evidence to this theory by constraining the formation temperature of dolomite from field samples. The research looked at magnesium isotopes and fluid inclusions recovered from a drill core obtained by drilling through a thick dolostone succession deposited between 500 to 400 million years ago in the Tarim Basin in Northwestern China.
Thermodynamic theory predicts that the extent of isotopic fractionation of magnesium diminishes as temperature increases. At low temperatures, the most common magnesium in a dolomite crystal is isotope 26. At higher temperatures, two types of magnesium — isotope 26 and isotope 25 — are equally distributed in the crystal. In a similar way, the chemical composition of fluid inclusions — bubbles of liquids or gases trapped inside a solid crystal — reflect the temperature at the moment of their formation.
The measurements and calculations show that most dolomite formed at temperatures from 45 to 189 degrees Celsius. Dolomitization starts in a near-surface environment as the carbonate sediment reacts with seawater under ambient conditions. Under shallow burial conditions, residual seawater trapped in the sediment continues to form dolomite at medium-high temperatures. Very hot hydrothermal fluids only play a role at medium to deep burial conditions.
The important role of temperature in the dolomitization process also explains why dolomite is so rarely formed today. Most dolomite formed when temperatures across the world's oceans were higher, providing ideal conditions for the accumulation of thick deposits. As Earth's temperature dropped over the past 100 million years, dolomite was replaced by now common calcium minerals.
The study, "Using Mg isotopes to constrain the formation temperature of dolomite," was published in the journal scientific reports.
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
3 hours ago
- Yahoo
Huawei chips are one generation behind US but firm finding workarounds, CEO says
By Brenda Goh BEIJING (Reuters) -Huawei Technologies' chips are one generation behind those of U.S. peers but the firm is finding ways to improve performance through methods such as cluster computing, Chinese state media quoted CEO Ren Zhengfei as saying on Tuesday. The chipmaker invests 180 billion yuan ($25.07 billion) in research annually and sees promise in compound chips - chips made from multiple elements - Ren said in an interview with the People's Daily newspaper of the governing Communist Party. There is "no need to worry about the chip problem", Ren said, addressing concerns stemming from U.S. export controls. The article, published on the front page of the newspaper, come as top U.S. and Chinese officials are set to resume trade talks for a second day in London where topics such U.S. tech restrictions on China are expected to be discussed. Since 2019, a slew of U.S. export curbs, aimed at curbing China's technological and military advancements, have restricted Huawei and other Chinese firms from accessing high-end chips and the equipment needed to produce them from abroad. Ren's comments are the first ever from him or Huawei about the company's advanced chipmaking efforts, which have become a flashpoint in U.S.-China tensions. Huawei is just one of many Chinese chipmakers, Ren said in the interview, adding: "The United States has exaggerated Huawei's achievements. Huawei is not that great. We have to work hard to reach their evaluation." "Our single chip is still behind the U.S. by a generation. We use mathematics to supplement physics, non-Moore's law to supplement Moore's law and cluster computing to supplement single chips and the results can also achieve practical conditions. Software is not a bottleneck for us," he said. Cluster computing is when multiple computers work together. Moore's law refers to the speed of chip advancement. HUAWEI'S LAUNCHES Huawei's Ascend series of AI chips compete in China with offerings from Nvidia, the global leader in AI chips. The U.S. commerce department last month said the use of Ascend chips would be a violation of export controls. Nvidia's AI chips are more powerful than Huawei's but the company has been barred by Washington from selling its most sophisticated chips to China, causing it to lose significant market share to Huawei. In April, Huawei launched "AI CloudMatrix 384", a system that links 384 Ascend 910C chips in a cluster that companies can use to train AI models, which has been described by analysts as able to outperform Nvidia's GB200 NVL72 system on some metrics. Dylan Patel, founder of semiconductor research group SemiAnalysis, said in an article that month that it meant that Huawei and China now had AI system capabilities that could beat Nvidia. Nvidia and the U.S. commerce department did not immediately respond to a request for comment on Ren's remarks. Ren also said about a third of Huawei's annual research spending went to theoretical research while the rest was spent on product research and development. "Without theory, there will be no breakthroughs, and we will not catch up with the United States." ($1 = 7.1802 Chinese yuan)
Yahoo
4 hours ago
- Yahoo
Huawei chips are one generation behind US but firm is finding workarounds, CEO says
BEIJING (Reuters) -Huawei Technologies' chips are one generation behind those of U.S. peers but the firm is finding ways to improve performance through methods such as cluster computing, Chinese state media quoted CEO Ren Zhengfei as saying on Tuesday. The chipmaker invests 180 billion yuan ($25.07 billion) in research annually and sees promise in compound chips - or chips made from multiple elements - Ren said in an interview in the People's Daily newspaper of the governing Communist Party. The public comments are the first from Ren or Huawei about the firm's advanced chip manufacturing efforts. U.S. export controls since 2019 have prevented Huawei from accessing high-end chips and equipment to manufacture them. Huawei has since marketed its Ascend series of artificial intelligence chips which compete in China with offerings from U.S. rival Nvidia, the global leader in AI chips. The U.S. commerce department last month said use of Ascend chips would be a violation of export controls. Huawei is just one of many Chinese chipmakers, Ren said in the interview. "The United States has exaggerated Huawei's achievements. Huawei is not that great. We have to work hard to reach their evaluation," he said. "Our single chip is still behind the U.S. by a generation. We use mathematics to supplement physics, non-Moore's law to supplement Moore's law and cluster computing to supplement single chips and the results can also achieve practical conditions," he said. Cluster computing is when multiple computers work together. Moore's law refers to the speed of chip advancement. ($1 = 7.1802 Chinese yuan renminbi)
Scientific American
9 hours ago
- Scientific American
Thermal Runaway Explains Why Waymo Cars Burned So Completely in the Recent Los Angeles Protests
Imagine watching a car burn until it seems to vaporize and the street itself begins to sag. That happened on Sunday in Los Angeles, when protesters torched at least five Waymo-branded Jaguar I-Pace robotaxis. When the smoke cleared, virtually the entire shell of each car—its roof, doors, hood, trunk and body panels—was gone, leaving only wheel rims and traces of aluminum lacing. Why did the fires cause such obliteration? The answer starts with the battery. Each I-Pace can carry roughly 90 kilowatt-hours of stored chemical energy, comparable to about 170 pounds (77 kilograms) of TNT. That energy is distributed across hundreds of lithium-ion pouch cells, which are sealed in flammable electrolyte and separated by polymer films as thin as snack-bag plastic. When any one cell is punctured or overheated—or set aflame with an incendiary device—chemical reactions generate more heat than the cell can shed, and neighboring cells follow in a chain reaction. This positive-feedback loop is called 'thermal runaway.' According to a 2024 study in the Journal of Power Sources, as the battery burns, its temperature can soar past 1,000 degrees Celsius. At that point, the pack becomes its own furnace. Aluminum sections of the car's floor surrender, liquefying at about 660 degrees C and taking the underbody with them. Magnesium parts—seat-base frames, the bracket that holds the steering column and the cross-car beam that is located behind the dashboard—flare bright white. Patches of magnesium can catch fire and burn fiercely. Plastics disappear as vapor, wheels lose their tire, and even the lidar mast on the roof quickly resembles an overcooked marshmallow. A 2025 study in Fire Technology and a 2023 study in Applied Energy noted that the placement of the battery on the floor—sometimes referred to as a 'skateboard architecture'—makes the floor the hottest zone. Thus, flames radiate upward and outward, cooking everything above. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. All the while, the battery cells vent hydrogen fluoride, a toxic, lung-searing gas documented in laboratory test burns of commercial lithium packs. Among the disturbing scenes from the recent Los Angeles protests, which erupted over federal immigration raids, are those in which protestors stood around the flaming Waymos. Historically, first responders without supplied-air protection have developed throat burns and breathing difficulties upon arriving at scenes with burning lithium-ion batteries. Depending on the hydrogen fluoride levels, an exposed person can begin coughing up blood within minutes. Whereas inhaling concentrations above roughly 30 parts per million (ppm) is immediately dangerous to health, 50 ppm may be fatal when inhaled for a half-hour to an hour, according to the U.S. Centers for Disease Control and Prevention. The Environmental Protection Agency estimates that exposure to 170 ppm for 10 minutes can be deadly. Measurements taken near electric-vehicle (EV) fires show peaks of 150 to 450 ppm, with levels during much of the fire hovering around 50 ppm. Firefighters call such blazes 'battery box fires,' and they hate them. Flame-retardant foams do little, and fire departments now favor high-pressure water lances or immersion pits. Dousing a runaway battery usually means lowering temperatures below the runaway threshold for every last battery cell—a task that, according to the Independent, can swallow 30,000 to 40,000 gallons (about 114,000 to 151,000 liters) of water. That's at least 40 times the amount of water required to extinguish a gasoline-car fire. If you hit the flames too lightly, stranded energy reignites hours later—a quirk the National Transportation Safety Board flagged in its 2020 report on EV firefighting hazards. Car designers have tried to address the danger. Software monitors cell temperatures and slows the rate at which batteries charge to prevent overheating. And it automatically cuts current if anything looks amiss. Yet even the best code cannot rewrite chemistry: in 2023 Jaguar recalled more than 6,400 I-Pace cars after at least a dozen of them caught fire from overheated batteries—which had likely shorted from manufacturing defects in their pouch cells. Six of the fires happened while the car was either plugged in or within a few minutes of being unplugged. Waymo's fleet got the update to better regulate the batteries, but software can't help when someone smashes one of the car's windows and lights up its interior with a 'makeshift flamethrower,' as reported by the Los Angeles Times. Could a Waymo van have burned just as thoroughly? Only with great effort. The company's earlier Chrysler Pacifica hybrids, which were phased out in 2023, stored a tenth of their battery energy in a steel-framed shell. Steel keeps its shape beyond 1,300 degrees C, so after a typical blaze, you would still recognize the carcass. To prevent thermal runaway, Teslas have batteries that use thousands of small cylindrical cells locked inside an aluminum tray with titanium undershields and built-in firebreaks. And most brands of electric-car batteries now sit in similarly rigid aluminum or steel boxes—and are shifting toward less volatile chemistries. Importantly, however, the scene in Los Angeles by no means indicates that electric cars are tinderboxes. A 2023 study in Finland showed that, mile for mile, they caught fire less often than gasoline cars. But when an EV does burn, the physics shift. You're no longer fighting a puddle of gasoline on asphalt; you're battling an energy-dense, metal-oxide battery that is determined to finish what it started—and in such cases, a single Molotov cocktail can turn a sleek robotaxi into a pool of molten alloy.
