A complete arc-trench system recognized in Gondwana sequences of the Antarctic Peninsula region

first_imgPrior to Late Triassic–Early Jurassic times, the geological history of the Antarctic Peninsula region was dominated almost entirely by Gondwana sequences that together comprised a major arc-trench system. Subduction complex, trench-slope-break and fore-arc basin sedimentation can all be recognized, and deposition was at least partly on early Palaeozoic or older continental crust. The only evidence for a contemporaneous magmatic arc situated in the Antarctic Peninsula at this time consists of patchy occurrences of metavolcanic rocks, possibly representing the frontal edge of the arc, and the major outcrop area of these rocks is believed to lie under the broad shallow continental shelf E of the Antarctic Peninsula. This is contrary to most current hypotheses in which a marginal basin, presumably floored by oceanic crust, is thought to crop out close to the E coast of the Antarctic Peninsula. However, the complete absence of substantial outcrops of pre-Jurassic volcanic rocks anywhere in eastern Antarctica and South Africa, which are the closest and most likely places in which these should exist, supports the new proposal. Moreover, the identification of back-arc elements of the arc-trench system (foreland fold-thrust belt and retro-arc foreland basin) in eastern Antarctica and South Africa greatly strengthens the likelihood of the arc cropping out in the area suggested. Towards the end of the Triassic and during the Early Jurassic Periods, an intense diastrophic event, or culmination of events, of orogenic magnitude occurred (Gondwanian orogeny), causing substantial redistribution of the pre-existing elements of the arc-trench system. In particular, all the fore-arc sequences were strongly deformed, some possibly for the first time (e.g. in the fore-arc basin), and became firmly accreted to the continental margin. Moreover, the magmatic foci migrated trenchwards to intrude the deformed rocks in the Antarctic Peninsula. Because many of the plutons were emplaced synkinematically, they often closely resemble ‘basement’ gneisses. The distinction between these rocks remains a serious problem in the Antarctic Peninsula and it can be solved only partially by radiometriclast_img read more

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Refudiate this

first_imgOxford University Press has named “refudiate” Word of the Year 2010, a spelling blunder made by Sarah Palin on her Twitter profile earlier this year.In July, Palin encouraged “peaceful Muslims” to “refudiate” plans for a Ground Zero mosque. She was subsequently mocked by political opponents and the media, to which she retorted, “English is a living language. Shakespeare liked to coin new words too”. Described as a fusion of the words ‘refute’ and ‘repudiate’, OUP said the word suggested “a general sense of ‘reject’”. Senior Lexicographer Christine Lindberg described Palin’s word as a “time capsule” of the past year.In 2009, the award went to “unfriend” and other contenders included “vuvuzela”, “gleek” and “nom nom”.last_img read more

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Seniors head to Peace Corps

first_imgNotre Dame ranked 18th among medium-sized schools this year to send the most volunteers to serve in the group, according to a University press release. The University jumped five spots on the list from last year as the Peace Corps prepares to mark its 50th anniversary, the release said. Notre Dame was included on this list for the past 11 years. Peace Corps recruiter Rok Teasley said Notre Dame averaged 23 applicants to the group in each of the past four years. Nineteen seniors applied already this year, and the rolling application process is ongoing. Current seniors wishing to join the 25 Notre Dame alumni currently serving in the Peace Corps must first complete a grueling application process, according to the release. Senior Claire Brosnihan said the process includes a lengthy online application, an hour-long interview with very specific and personal questions, and multiple steps of clearance, contributing to months of waiting. Brosnihan, a political science major with a minor in peace studies, said she would be stationed in French-speaking sub-Saharan Africa to work on a malnutrition-focused public health program. “The Peace Corps gives you a different perspective from South Bend, Indiana and Notre Dame,” Brosnihan said. “Putting all of your beliefs into action is a big part of it.” Brosnihan said she would like to work in international relations or at an international non-profit organization after her time in the Peace Corps. Senior Shannon Coyne will also join the Peace Corps after graduation. A political science and Arabic double major with a minor in peace studies, Coyne said she will be teaching English in either Jordan or Morocco. “I was attracted to the principles that underlie the mission of the [Peace Corps],” Coyne said. “I was interested in post-graduate service, and it seemed like a logical choice.” Coyne said her minor in Peace Studies prepared her for her time in the Peace Corps. “Peace Studies classes are good for helping you think about ways to promote international development,” Coyne said. “But more than my studies, my experiences outside the classroom really prepared me.” Coyne participated in service through the Center for Social Concerns and the Kellogg Institute, and traveled to Ghana and Cairo, Egypt through the University, which provided invaluable service experiences for her. Coyne said she is most interested in gender issues and will seek a master’s degree in development after leaving the Peace Corps in hopes of working for a non-governmental organization. Megan Conway, a 2006 Notre Dame graduate, also studied Peace Studies while she was a student. She joined the Peace Corps after graduation and is now at the University of Michigan Law School. Conway said a class on tropical African politics she took as an undergraduate piqued her interest in Africa. She was stationed in Cameroon, where she worked on public health initiatives. “We worked with potable water projects, AIDS education, basic health and hygiene and environmental education classes,” Conway said. “And I focused in pre-natal care projects.” Although her time in the Peace Corps was rewarding and worthwhile, Conway said she learned that international sustainable development, more specifically public health, was not the field for her. “I had a phenomenal experience, but I realized that I didn’t want to live abroad for the rest of my life,” Conway said. Conway said the unique undergraduate experience at Notre Dame contributed to her choice to join the Peace Corps. “I don’t think I would have joined the Peace Corps if I had attended one of the other universities I was thinking of,” Conway said. Notre Dame’s relationship can be attributed to the University’s mission to serve others, Coyne said. “It’s definitely the emphasis that Notre Dame students put on service,” Coyne said, “and taking what you learn in the classroom to give back to others.”last_img read more

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California regulators back major increase in renewables, ban on new natural gas plants

first_img FacebookTwitterLinkedInEmailPrint分享Reuters:California on Thursday adopted a new emissions target for its electric sector that would double the state’s clean energy capacity over the next decade and close the door to development of new natural gas plants, but green groups said the goal was not aggressive enough.The state’s Public Utilities Commission set a target of reducing greenhouse gas emissions to 46 million metric tons by 2030, 56% below 1990 levels. The goal outpaces the state’s overall goal of slashing emissions to 40% below 1990 levels by 2030.California electricity providers will need to develop nearly 25 gigawatts of renewable energy and battery storage to achieve the goal, nearly double the amount the state has currently, CPUC Commissioner Liane Randolph said in a statement. The agency anticipates 8,900 MW of energy storage will be included in that total, or about eight times more than existed in the entire United States at the end of 2018.Environmental groups had pressed for a more aggressive target of 30 MMT that would get the state closer to its 2045 goal of sourcing electricity exclusively from carbon-free sources. They favor a rapid shift away from fossil fuels to fight global climate change.In a win for green groups, the CPUC closed a loophole that would allowed development of new natural gas plants if paired with energy storage. Expansion of existing natural gas plants is allowed if paired with energy storage, however.New gas plants are allowed if they use biomethane, which comes from manure, landfills or wastewater and is interchangeable with gas drilled out of the ground. It cuts greenhouse gas emissions by ensuring significant volumes of methane, that would have been produced anyway, never reach the atmosphere.[Nichola Groom]More: California sets goal to double clean energy by 2030 California regulators back major increase in renewables, ban on new natural gas plantslast_img read more

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