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  • richardmitnick 9:30 am on September 14, 2022 Permalink | Reply
    Tags: "Igneous provinces": giant fingerprints of volcanic igneous rock., , "What Killed Dinosaurs and Other Life on Earth?", A series of eruptions in what is now known as Siberia triggered the most destructive of the mass extinctions about 252 million years ago., , , , , , Dartmouth-led study fortifies link between mega volcanoes and mass extinctions., Deccan Traps eruption, , , Large igneous provinces releasa gigantic pulses of carbon dioxide into the atmosphere and nearly choking off all life., , , , The eruption rate of the Deccan Traps in India suggests that the stage was set for widespread extinction even without the asteroid., The total amount of carbon dioxide being released into the atmosphere in modern climate change is still very much smaller than the amount emitted by a large igneous province., To count as “large” an igneous province must contain at least 100000 cubic kilometers of magma., Volcanic eruptions rocked the Indian subcontinent around the time of the great dinosaur die-off creating what is known today as the Deccan plateau.,   

    From Dartmouth College: “What Killed Dinosaurs and Other Life on Earth?” 

    From Dartmouth College

    9.12.22
    Harini Barath

    Dartmouth-led study fortifies link between mega volcanoes and mass extinctions.

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    The Mount Fagradalsfjall volcano, near Iceland’s capital of Reykjavík, erupted for six months in 2021, and also again in August. (Photo by Tanya Grypachevskaya/Unsplash Photo Community)

    The biological history of the Earth has been punctuated by mass extinctions that wiped out a vast majority of living species in a geological instant.

    Based on evidence in the fossil record, scientists have identified five such events that reshaped life on Earth, the most familiar of which brought about the demise of the mighty dinosaurs at the end of the Cretaceous Period 66 million years ago.

    What caused these catastrophes remains a matter of keen scientific debate. Some scientists argue that comets or asteroids that crashed into Earth were the most likely agents of mass destruction, while others point fingers at large volcanic eruptions.

    Assistant Professor of Earth Sciences Brenhin Keller belongs to the latter camp. In a new study published in PNAS [below], Keller and his co-authors make a strong case for volcanic activity being the key driver of mass extinctions. Their study provides the most compelling quantitative evidence so far that the link between major volcanic eruptions and wholesale species turnover is not simply a matter of chance.

    Four of the five mass extinctions are contemporaneous with a type of volcano called a flood basalt, the researchers say. These are a series of eruptions (or one giant one) that flood vast areas with lava in the blink of a geological eye, a mere million years. They leave behind giant fingerprints as evidence—extensive regions of step-like, igneous rock that geologists call large igneous provinces.

    To count as “large” an igneous province must contain at least 100,000 cubic kilometers of magma. For scale, the 1980 eruption of Mount St. Helens involved less than one cubic kilometer of magma.

    In fact, a series of eruptions in what is now known as Siberia triggered the most destructive of the mass extinctions about 252 million years ago, releasing a gigantic pulse of carbon dioxide into the atmosphere and nearly choking off all life. Bearing witness are the Siberian Traps, a large region of volcanic rock roughly the size of Australia.

    Volcanic eruptions also rocked the Indian subcontinent around the time of the great dinosaur die-off creating what is known today as the Deccan plateau. This, much like an asteroid strike, would have had far-reaching global effects, blanketing the atmosphere in dust and toxic fumes, asphyxiating dinosaurs and other life.

    “It seems like these large igneous provinces line up in time with mass extinctions and other significant climactic and environmental events,” says Theodore Green ’21, lead author of the paper.

    On the other hand, the researchers say, the theories in favor of annihilation by asteroid impact hinge upon the Chicxulub impactor, a space rock that crash-landed into Mexico’s Yucatan Peninsula around the same time that the dinosaurs went extinct.

    “All other theories that attempted to explain what killed the dinosaurs got steamrolled when the crater the asteroid had gouged out was discovered,” says Keller. But there’s very little evidence of similar impact events that coincide with the other mass extinctions despite decades of exploration, he points out.

    For his Senior Fellowship thesis, Green set out to find a way to quantify the apparent link between eruptions and extinctions and test whether the coincidence was just chance or whether there was evidence of a causal relationship between the two. Working with Keller and co-author Paul Renne, professor of Earth and planetary science at the University of California-Berkeley, Green turned to the supercomputers at the Dartmouth Discovery Cluster to crunch the numbers.

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    Discovery is a 3000+ core Linux cluster that is available to the Dartmouth research community.

    Discovery contains ‘C’ and FORTRAN compilers as well as third party applications. Requests to install additional application software are welcomed and should be directed to Research Computing.

    Job submissions on Discovery are submitted to a queue. A queuing system allows for more equitable allocation of resources and optimizes cpu usage. For more information see the Scheduling Jobs to Run page.

    Discovery is available for all Dartmouth faculty research including the Geisel School of Medicine, and professional schools.

    The researchers compared the best available estimates of flood basalt eruptions with periods of drastic species kill-off in the geological timescale, including but not limited to the five mass extinctions. To prove that the timing was more than a random chance, they examined whether the eruptions would line up just as well with a randomly generated pattern and repeated the exercise with 100 million such patterns. “Less than 1% of the simulated timelines agreed as well as the actual record of flood basalts and extinctions, suggesting the relationship is not just random chance,” says Green, who is now a graduate student at Princeton.

    But is this proof enough that volcanic flood basalts sparked extinctions? If there were a causal link, scientists expect that larger eruptions would entail more severe extinctions, but such a correlation has not been observed until now.

    By recasting how the severity of the eruptions is defined, the researchers make a convincing case to unequivocally incriminate volcanoes in their paper.

    Rather than considering the absolute magnitude of eruptions, they ordered the events by the rate at which they spewed lava and found that the ones with the highest eruptive rates did indeed cause the most destruction.

    “Our results make it hard to ignore the role of volcanism in extinction,” says Keller.

    3
    Examples of flood basalt volcanism can be seen in what are known as Grande Ronde flows exposed in Joseph Canyon on the Oregon-Washington border. (Photo courtesy of Brenhin Keller)

    The researchers ran the numbers for asteroids too. The coincidence of impacts with periods of species turnover was significantly weaker, and only worsened when the Chicxulub impactor was not considered.

    The eruption rate of the Deccan Traps in India suggests that the stage was set for widespread extinction even without the asteroid, says Green. The impact was the double whammy that loudly sounded the death knell for the dinosaurs, he adds.

    Flood basalt eruptions aren’t common in the geologic record, says Green. The last one of comparable scale happened about 16 million years ago in the Pacific Northwest. But there are other sources of emissions that pose a threat in the present day, the researchers say.

    “While the total amount of carbon dioxide being released into the atmosphere in modern climate change is still very much smaller than the amount emitted by a large igneous province, thankfully,” says Keller, “we’re emitting it very fast, which is reason to be concerned.”

    Green says that this rate of carbon dioxide emissions places climate change in the framework of historical periods of environmental catastrophe.

    Green describes Dartmouth’s Senior Fellowship program, which allows undergraduates to go beyond the curriculum in their senior year, as a unique opportunity to dive into a field of his choice and develop a taste for research.

    “This work is a great example of what Senior Fellows can achieve,” says Keller.

    Science paper:
    PNAS

    See the full article here .

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    Dartmouth College campus

    Dartmouth College is a private Ivy League research university in Hanover, New Hampshire. Established in 1769 by Eleazar Wheelock, Dartmouth is one of the nine colonial colleges chartered before the American Revolution and among the most prestigious in the United States. Although founded to educate Native Americans in Christian theology and the English way of life, the university primarily trained Congregationalist ministers during its early history before it gradually secularized, emerging at the turn of the 20th century from relative obscurity into national prominence.

    Following a liberal arts curriculum, Dartmouth provides undergraduate instruction in 40 academic departments and interdisciplinary programs, including 60 majors in the humanities, social sciences, natural sciences, and engineering, and enables students to design specialized concentrations or engage in dual degree programs. In addition to the undergraduate faculty of arts and sciences, Dartmouth has four professional and graduate schools: the Geisel School of Medicine, the Thayer School of Engineering, the Tuck School of Business, and the Guarini School of Graduate and Advanced Studies. The university also has affiliations with the Dartmouth–Hitchcock Medical Center. Dartmouth is home to the Rockefeller Center for Public Policy and the Social Sciences, the Hood Museum of Art, the John Sloan Dickey Center for International Understanding, and the Hopkins Center for the Arts. With a student enrollment of about 6,700, Dartmouth is the smallest university in the Ivy League. Undergraduate admissions are highly selective with an acceptance rate of 6.24% for the class of 2026, including a 4.7% rate for regular decision applicants.

    Situated on a terrace above the Connecticut River, Dartmouth’s 269-acre (109 ha) main campus is in the rural Upper Valley region of New England. The university functions on a quarter system, operating year-round on four ten-week academic terms. Dartmouth is known for its strong undergraduate focus, Greek culture, and wide array of enduring campus traditions. Its 34 varsity sports teams compete intercollegiately in the Ivy League conference of the NCAA Division I.

    Dartmouth is consistently cited as a leading university for undergraduate teaching by U.S. News & World Report. In 2021, the Carnegie Classification of Institutions of Higher Education listed Dartmouth as the only majority-undergraduate, arts-and-sciences focused, doctoral university in the country that has “some graduate coexistence” and “very high research activity”.

    The university has many prominent alumni, including 170 members of the U.S. Senate and the U.S. House of Representatives, 24 U.S. governors, 23 billionaires, 8 U.S. Cabinet secretaries, 3 Nobel Prize laureates, 2 U.S. Supreme Court justices, and a U.S. vice president. Other notable alumni include 79 Rhodes Scholars, 26 Marshall Scholarship recipients, and 14 Pulitzer Prize winners. Dartmouth alumni also include many CEOs and founders of Fortune 500 corporations, high-ranking U.S. diplomats, academic scholars, literary and media figures, professional athletes, and Olympic medalists.

    Comprising an undergraduate population of 4,307 and a total student enrollment of 6,350 (as of 2016), Dartmouth is the smallest university in the Ivy League. Its undergraduate program, which reported an acceptance rate around 10 percent for the class of 2020, is characterized by the Carnegie Foundation and U.S. News & World Report as “most selective”. Dartmouth offers a broad range of academic departments, an extensive research enterprise, numerous community outreach and public service programs, and the highest rate of study abroad participation in the Ivy League.

    Dartmouth, a liberal arts institution, offers a four-year Bachelor of Arts and ABET-accredited Bachelor of Engineering degree to undergraduate students. The college has 39 academic departments offering 56 major programs, while students are free to design special majors or engage in dual majors. For the graduating class of 2017, the most popular majors were economics, government, computer science, engineering sciences, and history. The Government Department, whose prominent professors include Stephen Brooks, Richard Ned Lebow, and William Wohlforth, was ranked the top solely undergraduate political science program in the world by researchers at The London School of Economics (UK) in 2003. The Economics Department, whose prominent professors include David Blanchflower and Andrew Samwick, also holds the distinction as the top-ranked bachelor’s-only economics program in the world.

    In order to graduate, a student must complete 35 total courses, eight to ten of which are typically part of a chosen major program. Other requirements for graduation include the completion of ten “distributive requirements” in a variety of academic fields, proficiency in a foreign language, and completion of a writing class and first-year seminar in writing. Many departments offer honors programs requiring students seeking that distinction to engage in “independent, sustained work”, culminating in the production of a thesis. In addition to the courses offered in Hanover, Dartmouth offers 57 different off-campus programs, including Foreign Study Programs, Language Study Abroad programs, and Exchange Programs.

    Through the Graduate Studies program, Dartmouth grants doctorate and master’s degrees in 19 Arts & Sciences graduate programs. Although the first graduate degree, a PhD in classics, was awarded in 1885, many of the current PhD programs have only existed since the 1960s. Furthermore, Dartmouth is home to three professional schools: the Geisel School of Medicine (established 1797), Thayer School of Engineering (1867)—which also serves as the undergraduate department of engineering sciences—and Tuck School of Business (1900). With these professional schools and graduate programs, conventional American usage would accord Dartmouth the label of “Dartmouth University”; however, because of historical and nostalgic reasons (such as Dartmouth College v. Woodward), the school uses the name “Dartmouth College” to refer to the entire institution.

    Dartmouth employs a total of 607 tenured or tenure-track faculty members, including the highest proportion of female tenured professors among the Ivy League universities, and the first black woman tenure-track faculty member in computer science at an Ivy League university. Faculty members have been at the forefront of such major academic developments as the Dartmouth Workshop, the Dartmouth Time Sharing System, Dartmouth BASIC, and Dartmouth ALGOL 30. In 2005, sponsored project awards to Dartmouth faculty research amounted to $169 million.

    Dartmouth serves as the host institution of the University Press of New England, a university press founded in 1970 that is supported by a consortium of schools that also includes Brandeis University, The University of New Hampshire, Northeastern University, Tufts University and The University of Vermont.

    Rankings

    Dartmouth was ranked tied for 13th among undergraduate programs at national universities by U.S. News & World Report in its 2021 rankings. U.S. News also ranked the school 2nd best for veterans, tied for 5th best in undergraduate teaching, and 9th for “best value” at national universities in 2020. Dartmouth’s undergraduate teaching was previously ranked 1st by U.S. News for five years in a row (2009–2013). Dartmouth College is accredited by The New England Commission of Higher Education.

    In Forbes’ 2019 rankings of 650 universities, liberal arts colleges and service academies, Dartmouth ranked 10th overall and 10th in research universities. In the Forbes 2018 “grateful graduate” rankings, Dartmouth came in first for the second year in a row.

    The 2021 Academic Ranking of World Universities ranked Dartmouth among the 90–110th best universities in the nation. However, this specific ranking has drawn criticism from scholars for not adequately adjusting for the size of an institution, which leads to larger institutions ranking above smaller ones like Dartmouth. Dartmouth’s small size and its undergraduate focus also disadvantage its ranking in other international rankings because ranking formulas favor institutions with a large number of graduate students.

    The 2006 Carnegie Foundation classification listed Dartmouth as the only “majority-undergraduate”, “arts-and-sciences focus[ed]”, “research university” in the country that also had “some graduate coexistence” and “very high research activity”.

    The Dartmouth Plan

    Dartmouth functions on a quarter system, operating year-round on four ten-week academic terms. The Dartmouth Plan (or simply “D-Plan”) is an academic scheduling system that permits the customization of each student’s academic year. All undergraduates are required to be in residence for the fall, winter, and spring terms of their freshman and senior years, as well as the summer term of their sophomore year. However, students may petition to alter this plan so that they may be off during their freshman, senior, or sophomore summer terms. During all terms, students are permitted to choose between studying on-campus, studying at an off-campus program, or taking a term off for vacation, outside internships, or research projects. The typical course load is three classes per term, and students will generally enroll in classes for 12 total terms over the course of their academic career.

    The D-Plan was instituted in the early 1970s at the same time that Dartmouth began accepting female undergraduates. It was initially devised as a plan to increase the enrollment without enlarging campus accommodations, and has been described as “a way to put 4,000 students into 3,000 beds”. Although new dormitories have been built since, the number of students has also increased and the D-Plan remains in effect. It was modified in the 1980s in an attempt to reduce the problems of lack of social and academic continuity.

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  • richardmitnick 5:15 pm on February 10, 2017 Permalink | Reply
    Tags: , , Deccan Traps eruption,   

    From COSMOS: “Two huge magma plumes fed the Deccan Traps eruption” 

    Cosmos Magazine bloc

    COSMOS

    10 February 2017
    Kate Ravilious

    1
    Thick lava flows in Hawaii are nothing compared to the mammoth rivers of hot rock that rolled across in India in the late Cretaceous. New research suggests those flows were fed by two magma sources. Justinreznick / Getty Images

    Some 65 million years ago, the skies over India darkened as one of Earth’s biggest volcanic eruptions burbled from below. It rumbled on for millions of years, blocking out sunlight and casting a chill globally, to produce what we know today as the Deccan Traps.

    Many believe the eruption sent the dinosaurs into severe demise before an asteroid collision finally finished them off. But just how the Earth produced such vast volumes of lava (covering an area greater than the Australian states of New South Wales and Victoria combined) has remained a bit of a mystery. Now a new study by a pair of geologists in Canada shows that the eruption may have been fed by not one, but two deep mantle plumes.

    Like the hot air that rises to create a thundercloud, mantle plumes are thought to be narrow regions of convection that fast-track hot material all the way up from the core-mantle boundary and through the Earth’s 2,900-kilometre-thick layer of hot rock called the mantle.

    There are thought to be a number of active mantle plumes today, some of which have created a chain of volcanic islands as the oceanic plate glides across the plume top. The Hawaiian-Emperor seamount chain, the Easter Islands and the Walvis Ridge (culminating in the island of Tristan da Cunha) are just a few examples.

    By calculating past movements of tectonic plates, scientists have shown that the mantle plume currently underneath the Indian Ocean Island of Réunion was probably responsible for melting the mantle underneath the Deccan region 66 million years ago. But scientists have remained perplexed as to how one mantle plume could produce such a prodigious volume of melt.

    Petar Glišović and Alessandro Forte from the University of Quebec in Montréal, Canada, decided to revisit the Deccan conundrum using a model of mantle convection and running it in reverse for 70 million years.

    “This is a really hard problem as it is impossible to undo heat diffusion,” explains James Wookey, a geophysicist at the University of Bristol in the UK, who wasn’t involved with the study.

    So the pair ran many iterations of their model, with each scenario starting 2.5 million years ago with a different mantle structure configuration, and run forwards until one produced current mantle conditions.

    Taking the best fit and rewinding mantle dynamics by 70 million years, Glišović and Forte’s model showed that the Réunion mantle plume was situated underneath the Deccan region of India, as expected, but to their surprise there was also another mantle plume nearby at that time, responsible for feeding the volcanism on the East African island of Comoros today.

    Publishing in Science, Glišović and Forte calculated that the combined heat of the Réunion and Comoros mantle plumes would have been sufficient to melt around 60 million cubic kilometres of mantle at the time of the eruption; more than enough to feed the Deccan Traps. “We see mantle plumes merging and splitting in our forward running models of mantle convection, so the idea that these two plumes merged in the past is certainly plausible,” says Wookey.

    The model also shows that the Comoros plume had lost most of its heat by 40 million years ago, while the Réunion mantle plume ran out of steam around 20 million years ago. Today, both plumes are mere shadows of their former selves. But Wookey cautions against taking the findings too literally, adding: “the physics of the model is reasonable, but whether the mantle movements are precisely what the Earth actually did is another matter.”

    See the full article here .

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