Latest news with #InternationalOceanDiscoveryProgram
Yahoo
30-04-2025
- Science
- Yahoo
Scientists Drilled Deeper Into Mantle Than Ever Before
"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." To understand the mantle—the largest layer of Earth's rocky body—scientists drill deep cores out of the Earth. Scientists drilled the deepest core yet and recovered serpentinized peridotite that forms when saltwater interacts with mantle rock. Although this is the deepest into the mantle scientists have ever drilled, the mission didn't uncover pristine mantle that lies beyond the Mohorovičić discontinuity, or Moho, boundary. If you want to understand the geology of our home planet, studying the mantle is a great place to start. Separating the planet's rocky crust and the molten outer core, the mantle makes up 70 percent of the Earth's mass and 84 percent of its volume. But despite its outsized influence on the planet's geologic processes, scientists have never directly sampled rocks from this immensely important geologic layer. And that's understandable, especially when you consider that the crust is roughly 9 to 12 miles thick on average. Luckily, that average contains outliers—areas of the world where the crust is actually incredibly thin and faulting exposes the mantle through cracks. One such area is the Mid-Atlantic Ridge, specifically near an underwater mountain called the Atlantis Massif. On the south side of this massif is an area known as the Lost City—a hydrothermal field whose vent fluids are highly alkaline and rich in hydrogen, methane, and other carbon compounds. This makes the area a particularly compelling candidate for explaining how early life evolved on Earth. Additionally, it contains mantle rock that interacts with seawater in a process known as 'serpentinization,' which alters the rock's structure and gives it a green, marble-like appearance. It was here, 800 meters south of this field, in May 2023 that members of the International Ocean Discovery Program (IODP)—aboard the JOIDES Resolution, a 470-foot-long research vessel rented by the U.S. National Science Foundation—extracted a 1,268-meter core containing abyssal peridotites, which are the primary rocks that make up the Earth's upper mantle. The results of the study were published in the journal Science. Although this makes this particular drill core the deepest sample of the mantle yet, going that deep into the rock wasn't the goal of this record-breaking expedition. 'We had only planned to drill for 200 meters, because that was the deepest people had ever managed to drill in mantle rock,' Johan Lissenberg, a petrologist at Cardiff University and co-author of the study, told Nature. He said that the drilling was so easy that they progressed three times faster than usual. The team eventually drilled a staggering 1,268 meters, and only stopped due to the mission's limited operations window. Andrew McCaig—study co-author and University of Leeds scientist—said in an article from The Conversation that, according to a preliminary analysis of the rock, the core's composition contains a variety of peridotite called harzburgite that forms via partial melting of mantle rock. It also contained rocks known as gabbros, which are coarse-grained igneous rocks. Both of these rocks then chemically reacted with seawater, changing their composition. While this core represents an incredibly opportunity to learn more about the Earth's mantle, as well as give an in-depth look at the geologic substrate upon which the Lost City rests, the mission didn't quite complete the 'grand challenge' of crossing the Mohorovičić discontinuity. Otherwise known as the Moho, the Mohorovičić discontinuity is recognized as the true boundary between the crust and pristine mantle. Future missions could continue exploring this site near the Atlantis Massif, but sadly, those missions won't include JOIDES Resolution—the NSF declined to fund more core drilling past 2024. Just as scientists are finally knocking on the door to the Earth's most ubiquitous geologic layer, the future of these kinds of drilling missions is now uncertain. You Might Also Like Can Apple Cider Vinegar Lead to Weight Loss? Bobbi Brown Shares Her Top Face-Transforming Makeup Tips for Women Over 50
The Hindu
29-04-2025
- Science
- The Hindu
Changes in monsoon affect marine productivity in Bay of Bengal: study
Strong and weak monsoons can influence marine productivity in the Bay of Bengal, a study exploring fluctuations in the Indian Summer Monsoon (ISM) over the past 22,000 years has found. Marine productivity is a proxy for plankton growth – the main source of nourishment for aquatic life. The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused warming. The study, which appears in the peer-reviewed, Nature Geoscience, brought together scientists from India, China, Europe and the United States. 'By analysing their chemistry and tracking the abundance of certain types that thrive in productive waters, we reconstructed long-term changes in rainfall, ocean temperatures and marine life in the Bay of Bengal,' said Kaustubh Thirumalai, of the University of Austin and lead author of the study. 'Together, these chemical signals helped us understand how the monsoon and ocean conditions responded to global climate changes over the past 22,000 years.' Despite covering less than 1% of the world's ocean area, the Bay of Bengal provides nearly 8% of global fishery production. Its nutrient-rich coastal waters are vital to the densely populated communities along its shores, many of whom rely heavily on fisheries for food and income. 'Millions of people living along the Bay of Bengal rely on the sea for protein, particularly from fisheries,' said Yair Rosenthal, of the Rutgers University and a co-author. 'The productivity of these waters – the ability of the ocean to support plankton growth – is the foundation of the marine food web. If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks and threatening food security for coastal communities.' The study found that both abnormally strong and weak monsoons throughout history caused major disruptions in ocean mixing, leading to a 50% reduction in food for marine life in the surface waters. This occurs because extreme monsoon conditions interfere with the vertical movement of nutrient-rich waters from the deep ocean to the surface, where plankton—the base of the food chain—flourish. To reconstruct past ocean conditions, scientists analysed fossilised shells of foraminifera, tiny single-celled marine organisms that record environmental data in their calcium carbonate shells. These microfossils were retrieved from seafloor sediments by scientists aboard the JOIDES Resolution, a research ship operating under the International Ocean Discovery Program. The researchers found that marine productivity declined sharply during periods like Heinrich Stadial 1 (a cold phase between 17,500 and 15,500 years ago) and the early Holocene (about 10,500 to 9,500 years ago), when monsoons were either unusually weak or strong. Monsoon rainfall directly affects river run-off into the Bay of Bengal, altering ocean salinity and circulation. When too much freshwater builds up at the surface, it prevents nutrient mixing. Conversely, weak monsoons reduce wind-driven mixing, also starving surface waters of nutrients. 'Both extremes threaten marine resource availability,' Mr. Thirumalai said. By comparing ancient patterns with modern ocean data and climate model projections, researchers identified 'worrying' similarities, the authors said in a statement. Future scenarios suggest warmer surface waters and stronger freshwater run-off—conditions linked to past drops in marine productivity. Additionally, weaker future winds may fail to break through ocean stratification and restore nutrient cycling.
The Hindu
29-04-2025
- Science
- The Hindu
Changes in monsoon strength affects marine productivity in Bay of Bengal
Strong and weak monsoons can influence marine productivity in the Bay of Bengal, a study exploring fluctuations in the Indian Summer Monsoon (ISM) over the past 22,000 years has found. Marine productivity is a proxy for plankton growth – the main source of nourishment for aquatic life. The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused warming. The study, which appears in the peer-reviewed, Nature Geoscience, brought together scientists from India, China, Europe and the United States. 'By analysing their chemistry and tracking the abundance of certain types that thrive in productive waters, we reconstructed long-term changes in rainfall, ocean temperatures and marine life in the Bay of Bengal,' said Kaustubh Thirumalai, of the University of Austin and lead author of the study. 'Together, these chemical signals helped us understand how the monsoon and ocean conditions responded to global climate changes over the past 22,000 years.' Despite covering less than 1% of the world's ocean area, the Bay of Bengal provides nearly 8% of global fishery production. Its nutrient-rich coastal waters are vital to the densely populated communities along its shores, many of whom rely heavily on fisheries for food and income. 'Millions of people living along the Bay of Bengal rely on the sea for protein, particularly from fisheries,' said Yair Rosenthal, of the Rutgers University and a co-author. 'The productivity of these waters – the ability of the ocean to support plankton growth – is the foundation of the marine food web. If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks and threatening food security for coastal communities.' The study found that both abnormally strong and weak monsoons throughout history caused major disruptions in ocean mixing, leading to a 50% reduction in food for marine life in the surface waters. This occurs because extreme monsoon conditions interfere with the vertical movement of nutrient-rich waters from the deep ocean to the surface, where plankton—the base of the food chain—flourish. To reconstruct past ocean conditions, scientists analysed fossilised shells of foraminifera, tiny single-celled marine organisms that record environmental data in their calcium carbonate shells. These microfossils were retrieved from seafloor sediments by scientists aboard the JOIDES Resolution, a research ship operating under the International Ocean Discovery Program. The researchers found that marine productivity declined sharply during periods like Heinrich Stadial 1 (a cold phase between 17,500 and 15,500 years ago) and the early Holocene (about 10,500 to 9,500 years ago), when monsoons were either unusually weak or strong. Monsoon rainfall directly affects river run-off into the Bay of Bengal, altering ocean salinity and circulation. When too much freshwater builds up at the surface, it prevents nutrient mixing. Conversely, weak monsoons reduce wind-driven mixing, also starving surface waters of nutrients. 'Both extremes threaten marine resource availability,' Mr. Thirumalai said. By comparing ancient patterns with modern ocean data and climate model projections, researchers identified 'worrying' similarities, the authors said in a statement. Future scenarios suggest warmer surface waters and stronger freshwater run-off—conditions linked to past drops in marine productivity. Additionally, weaker future winds may fail to break through ocean stratification and restore nutrient cycling.
