World Cup Costa Rica qualifies for World Cup in dramatic fashion Dejan Kalinic Last updated 2 years ago 10:17 10/8/17 FacebookTwitterRedditcopy Comments(0) EZEQUIEL BECERRA World Cup Costa Rica Costa Rica v Honduras Honduras WC Qualification CONCACAF A late goal from Kendall Waston against Honduras saw the Ticos secure their place at the 2018 World Cup Costa Rica booked a spot at the 2018 World Cup after a dramatic late equaliser against Honduras on Saturday.A powerful header from Eddie Hernandez put Honduras in front in the 66th minute in the World Cup qualifier in San Jose, in a clash pushed back a day due to Tropical Storm Nate.Spain 5/1 to beat Israel 2-0 Article continues below Editors’ Picks Why Barcelona god Messi will never be worshipped in the same way in Argentina Lyon treble & England heartbreak: The full story behind Lucy Bronze’s dramatic 2019 Liverpool v Man City is now the league’s biggest rivalry and the bitterness is growing Megan Rapinoe: Born & brilliant in the U.S.A. But there was late drama as the home side levelled in the fifth minute of additional time, Kendall Waston rising highest to head in a Bryan Ruiz cross.With one match remaining in CONCACAF qualifying, the point sealed Costa Rica’s spot in Russia.Costa Rica (16 points) will finish second to Mexico (21), with those as the only two CONCACAF sides to have booked their tickets to Russia.It marks the fifth time Costa Rica have qualified for the World Cup, having reached the quarter-finals in Brazil in 2014.They became the 13th team to qualify for the 2018 showpiece, joining Russia, Brazil, Iran, Japan, Mexico, Belgium, South Korea, Saudi Arabia, Germany, England, Spain and Nigeria.QUALIFIED!Congratulations Costa Rica!The 2014 FIFA World Cup quarter-finalists are heading for Russia! #WCQ pic.twitter.com/SlvcdJ4B9Z — #WCQ (@FIFAWorldCup) October 8, 2017 The draw also sees Panama remain in the playoff position in CONCACAF on 10 points, level with Honduras which could have jumped up to fourth had the side been able to hang on for the win. The United States currently occupies third place in the table after beating Panama 4-0 on Friday night, which leaves Bruce Arena’s side in control of its own destiny heading into the final match of the Hexagonal. With just two points between the three sides fighting for the final automatic berth from CONCACAF and one playoff place, there is still plenty to play for on the final matchday. The USA will be on the road against Trinidad and Tobago, with Honduras hosting Mexico and Panama hosting Costa Rica.
AP, June 8, 2018 SAN DIEGO (AP) — A California appeals court has upheld a San Diego city ordinance that closes a picturesque children’s beach for nearly half the year so that seals may give birth, nurse and wean their pups.In a decision filed Thursday, the 4th District Court of Appeal reversed a lower court ruling that set aside the ordinance governing Children’s Pool Beach in La Jolla, an affluent seaside community in San Diego.Thursday’s ruling will keep the beach closed between Dec. 15 and May 15 every year. Violators face misdemeanor penalties of up to $1,000 in fines or six months in jail.The Children’s Pool is an artificial cove that was used as a swimming hole for youngsters until seals began moving in during the 1990s — spurring a years-long feud between supporters of the animals and those who want beach access.In 2014, the City Council approved closing the beach for part of the year after other efforts to protect the seals during their breeding season were unsuccessful. The California Coastal Commission issued a permit allowing that action.Visitors to the area often walk up to the seals, pose for selfies with them and mimic their barking noises. When they’re disturbed, seals can abandon their pups, give birth prematurely or miscarry, or become frightened and accidentally stampede babies. They’ve also nipped at humans.The group Friends of the Children’s Pool sued San Diego and the coastal commission, arguing that the Marine Mammal Protection Act gives the federal government jurisdiction over marine mammals, not local governments. The group won a trial court ruling in the matter.The appeals court rejected the group’s argument and the lower court’s ruling, saying nothing in the protection act pre-empts a state’s ability to regulate access to its own property.“(The ordinance) is not directed to conservation or taking of seals,” according to the ruling. “Rather, it is a land-use regulation, which falls within a traditional state police power.”Coastal commission Chair Dayna Bochco said in a statement that the ruling shows the commission “made the right decision to protect the seals and public safety at Children’s Pool.”“This agency will continue to safeguard our precious marine resources as we have for the last 40 years,” Bochco said.Friends of the Children’s Pool says on its website that the group doesn’t want to force seals to be removed from the beach, “only to force the city to find a better way to manage shared use within the law.”“The seals had prospered for over 20 years sharing habitat with people. If the City still insists shared use is impractical, it can revert to restoration of Children’s Pool as originally entrusted, not buried under 10 feet of sand,” the group says.Or, the group says, San Diego “must repatriate the seals to the wild, for their safety, per federal recommendations and procedures.”“San Diego had no right to create a pen for them on state trusted land to exploit them for a tourist attraction,” the group says. Posted: June 8, 2018 AP Court: Popular San Diego beach can keep closing for seals Categories: Local San Diego News FacebookTwitter
TEWKSBURY, MA — On Wednesday, June 20, 2018 the Tewksbury Police Department arrested Robert J. Gorski, 26, of 85 Baystate Rd., Tewksbury on a warrant for Receiving Stolen Property (subsequent offense).After setting up a surveillance operation at 85 Baystate Rd (Gorski’s residence) with an arrest warrant and search warrant in hand, Detectives observed a 2016 Black Ford Escape (Ma. Reg. 6PRY70) leaving the residence. Detectives observed Robert Gorski sitting in the passenger seat of the vehicle which led to a motor vehicle stop a short distance from the residence and his arrest without incident.Mr. Gorski is a suspect in a string of recent car breaks in the neighborhood where he resides and his arrest/warrant was the result of an ongoing investigation. The search warrant was executed at 85 Baystate Rd after his arrest and items linked to the recent car breaks were located. Mr. Gorski was held overnight and transported to Lowell District Court in the morning for arraignment.The Tewksbury Police Department urges any citizens who suspect criminal activity to call the Dispatch Center @ 978-851-7373. If you wish to remain anonymous please call the Tip Line @ 978-851-0175 or send an email to firstname.lastname@example.org.Robert Gorski(NOTE: The above press release is from the Tewksbury Police Department.)Like Wilmington Apple on Facebook. Follow Wilmington Apple on Twitter. Follow Wilmington Apple on Instagram. Subscribe to Wilmington Apple’s daily email newsletter HERE. Got a comment, question, photo, press release, or news tip? Email email@example.com.Share this:TwitterFacebookLike this:Like Loading… RelatedSuspects In Recent String Of Wilmington Break-Ins Arrested After Turning Themselves InIn “Featured”Wilmington K9 Ridic Helps Catch Bad Guy In AndoverIn “Government”WANTED: Fugitive Dumped Stolen Car In WilmingtonIn “Government”
High CourtA High Court (HC) bench on Tuesday refused to hear the death reference and appeals in the sensational 10-truck arms haul case where 14 people were sentenced to death.The bench of justice Bhabani Prasad Singha and justice Md Kamrul Hossain Mollah expressed its inability as justice Bhabani Prasad Singha acted for several days as the judge of the case’s trial court, said assistant attorney general Nirmal Kumar Das.He said the judge expressed his inability on moral grounds.The death reference and appeals will now be sent to the chief justice who will assign a new bench for the hearing.On 1 April 2004, 10 trucks of arms were seized at the Chittagong Urea Fertiliser Ltd jetty.Two cases — one for arms and another for smuggling — were filed with Karnaphuli police station the following day.Fifty people were made accused in the arms case and 52 in the other one.Fourteen people, including former Jamaat-e-Islami chief Motiur Rahman Nizami, former state minister for home Lutfozzaman Babar, Indian separatist outfit United Liberation Front of Assam (ULFA) chief Paresh Barua, former DGFI director Rezzakul Haider Chowdhury and former National Security Intelligence director general Abdur Rahim were sentenced to death in one of the cases.
Share Michael Stravato for The Texas TribuneEvacuees flee flooding in a boat with a nearly submerged Houston sign behind them, on Aug, 29, 2017. Hurricane Harvey made landfall as a Category 4 storm with winds of 130 miles per hour four days prior.A commission convened by Gov. Greg Abbott to focus on rebuilding after Hurricane Harvey issued a report Thursday saying the state should take a series of steps to prepare for the next big storm, including improving local disaster response procedures and considering major infrastructure projects designed to harden the state against future disasters.The 175-page report, which Abbott called a “roadmap” for the Texas Legislature and local communities moving forward, came more than a year after Harvey inundated parts of the Houston area with more than 60 inches of rain. It was compiled by the Commission to Rebuild Texas, which was overseen by Texas A&M University System Chancellor John Sharp.“We knew when the hurricane hit, that Hurricane Harvey would deserve a Texas-size response,” Abbott said. “By following the recommendations in the report, Texas will be better prepared to deal with future disasters.”The report praised Texas’ response to Harvey, saying that “Texas is a national leader in responding to disasters.” But it also highlighted problems that arose, including uneven preparedness among local jurisdictions and communication problems among first responders. And it said that “Hurricane Harvey was a warning that we should heed.”“The enormous toll on individuals, businesses and public infrastructure should provide a wakeup call underlining the urgent need to ‘future-proof’ the Gulf Coast — and indeed all of Texas — against future disasters,” the report said in its executive summary.The plan identified more than 4,000 potential projects geared toward that future-proofing. One recommendation is to consider “buy-outs” of properties that are consistently or severely damaged, while underscoring that homeowners would need to request or volunteer for a buy-out. The report points to the Federal Emergency Management Agency’s Hazard Mitigation Grant Program, which has already spent $555 million in Texas to acquire or elevate more than 4,000 properties.Another possible strategy the report identifies is the prevention of home building in “vulnerable locations in the first place.” In April, the Houston City Council approved changes to floodplain regulations to reduce future damage.The report also discusses the benefits of building a “coastal spine” to protect the greater Houston area from a hurricane’s storm surge. Depending on a given storm’s strength, the report identified savings of “$400 million to $7 billion” per storm if a coastal spine system was built. And it called for placing public infrastructure such as sewer and water lines in “the least flood-prone areas within a community.”But the report didn’t go into details for how to pay for each individual project, many of which would require federal or local funds.Sitting next to Abbott, Sharp talked about the importance of making sure someone in every county in the state was trained in disaster management. He also talked about institutionalizing the use of extension agents from the Texas A&M AgriLife Extension Service to better support the Texas Division of Emergency Management.Harvey made landfall in August 2017. It left more than 90 people dead and caused extreme flooding in Houston and other areas near the coast. The storm was the costliest U.S. disaster in 2017 and the second costliest in U.S. history.In November, an interim report from the Texas Senate’s budget-writing panel estimated that state government has already spent $2.7 billion on Harvey recovery. More than 80 percent of that came from federal sources.The report was released on the same day the Texas Water Development Board released a state flood assessment. The 54-page report, also compiled for the Legislature, identifies strategies like improved flood mapping and modeling, and recommended coordinated watershed-based planning, to prepare for future floods.While the assessment said Texas “does not have a systematic method for identifying and calculating flood mitigation costs,” it estimated a total need up to $36 billion for flood mitigation. Part of that cost, the assessment said, could be met using funding from local, state or federal programs.This article was originally published in The Texas Tribune, a nonprofit, nonpartisan media organization that informs Texans — and engages with them — about public policy, politics, government and statewide issues. Disclosure: The Texas A&M University System has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune’s journalism. Find a complete list of them here.
By Renee Foose, Special to the AFROMost people would agree that being born into homelessness is not a good situation. Few, if any, would consider such a circumstance to be a blessing. However, one Baltimore native falls into the category of feeling blessed to have been born homeless to a single mom who struggled from alcoholism. Richard Antoine White has used his early life experiences to shape his journey from being cold, barefoot, hungry and alone in the Sandtown-Winchester community in West Baltimore to healthy, happy, educated, and playing symphony music on a world stage.Richard Antoine White (Courtesy Photo)Born to a single mom who battled addiction, White was often left alone to fend for himself as he wandered the streets looking for his mother. When searching for her, he’d also scan storm drains and sidewalks looking for spare change. “Eventually when I had a dollar, I would go buy chicken gizzards so I could eat,” White told the AFRO. “I would keep gizzard meat under my tongue all day, to help with hunger.”White recalls sleeping under trees, and on park benches as a child not having reached school age. “There is a problem when everyone sees a child running around without shoes and sleeping in a park,” White said. He also has scars on his torso from being bitten by rats while sleeping, he said.After police found him sleeping on a very cold morning he was placed in foster care. His new foster parents were the same foster parents that raised his mother. and they were eager to adopt him. “He didn’t have much trouble adjusting, my children and the other children we had, helped him quite a bit,” said foster parent Richard McClain, Sr. McClain, who is active in his church choir, doesn’t play an instrument but supported White’s desire to learn how to play music. “We put him in school and he wanted to play music, so I got him a trumpet,” said McClain.Richard Antoine White (Courtesy Photo)Eventually a music teacher believed White had strong lungs and natural strength, so he was given a sousaphone, a lighter version of a tuba. White didn’t read music well, so he listened to cassette tapes of tuba players and practiced until he could mimic the sound. “I played for fun with no real interest in being a musician,” White said. “I wanted to play football until I broke my hip in a street game, then I became more serious about playing music,” he said.When it came time to enter high school, White took his basic music skills and a borrowed sousaphone to audition for a seat at the Baltimore School for the Performing Arts. Unfortunately, he missed the audition date, and showed up to an empty school. Luckily for White, he was greeted by Chris Ford, the head of the music department.“He was an intriguing sight, a kid on crutches carrying a plastic sousaphone,” Ford told the AFRO. Ford, now the director of Baltimore School for the Arts, said he chose to give White a chance to audition because he sensed White’s determination. “He couldn’t sight read music, and his ability to sing back pitches was weak; but he had a way of manipulating sound in a meaningful way,” Ford said. White was granted admission to the school and began playing the tuba.As he planned to further his musical talents, he worked as an usher at the Baltimore Symphony Orchestra. During concerts, White paid close attention to the principal tubist, David Fedderly. “During performances, most ushers congregate in lobby areas; Richard didn’t do that. He’d stay and listen to the music and after the performance he would find me and ask questions,” Fedderly said. “I knew he wanted to learn tuba and I knew he wanted to gain admission into a good college program to become a good musician,” Fedderly said. Fedderly, who also taught music, became White’s teacher at The Peabody Institute of Johns Hopkins University, where he worked closely with White to master the tuba. Upon earning his bachelor’s degree, White enrolled at Indiana University to pursue graduate studies. After just a few years, White earned a doctorate in tuba performance and became the first African American at Indiana University to do so. The American Federation of Musicians report that African Americans make up less than four percent of symphony musicians world-wide, and White became one of the elites after accepting a one-year position with the New Mexico Symphony Orchestra (NMSO) in Albuquerque. New Mexico became his new home and he earned tenure with the orchestra, in addition to teaching at the University of New Mexico.In 2011, NMSO filed for bankruptcy and White was out of a job. The survival instincts he learned as a homeless child kicked in, and White did something few would consider. He met with university athletic staff and proposed a scenario to help the marching band with breathing techniques and choreography. “He saw an opportunity and presented a way how he could help the university,” said Chad Simons, associate professor and director of marching bands University of New Mexico. White’s pitch worked, and he was hired as the assistant marching band director. “His motivation and positive message are powerful for nineteen-year-olds to hear,” said Simons.White is now a tenured faculty member at the University of New Mexico. After the collapse of the NMSO, White was one of several musicians to form the New Mexico Philharmonic, where he is the principal tubist.His personal journey through destitution to doctoral studies only became widely known after two Baltimore-based filmmakers contacted Ford with an interest in creating a documentary about arts education being underfunded. Darren Durlach and David Larson are the founders of Early Light Media. Their inspiring and award-winning films capture the human element in a way that compels viewers to be open to new perspectives. When Ford suggested the filmmakers contact White, they were unaware of all the nuances of his journey, but quickly saw a powerful message. “Our challenge in making the film was finding a way to tell the story in an authentic way,” said Durlach. “The story is one of persistence, and how a teacher can make all the difference in someone’s life,” he said.Durlach and Larson documented White’s journey and compelling message of hope, help and hard work. The film, RAW (White’s initials) Tuba is a contender for several independent film festival awards around the nation.White considers his journey a blessing and wants his message to inspire others to find hope, commit to a work ethic, and never give up. To hear music performed by White, visit his web page at RawTuba.com.
Comparison of measured and time-integrated Th/U in zircon. The panel a is for oldest known terrestrial igneous zircons, whereas panel b is for oldest known terrestrial detrital zircons from Western Australia. Time-integrated means calculated from measured 208Pb/206Pb ratio and 207Pb/206Pb age. Corresponding data can be found in Credit: Nature Communications, doi: 10.1038/s41467-019-10382-y LEFT: Influence of Pb mobility on present-day 207Pb/206Pb ages and time-integrated Th/U. The panel (a) shows the effect of Pb-loss and Pb-addition on determined 207Pb/206Pb ages for a 4430 Ma zircon with original Th/U of 1, whereas the panel (b) presents the effect of Pb-loss and Pb-addition on time-integrated Th/U for the same zircon. Percentages next to the dotted-curves correspond to the degree of Pb-loss or Pb-addition. The age of perturbation refers to the age at which the Pb is lost or added. Note that Pb-addition corresponds to local increase in radiogenic Pb concentration and not addition of common Pb. This figure illustrates the great sensitivity of 207Pb/206Pb ages to Pb mobility whereas it has a limited effect on time-integrated Th/U. RIGHT: Time-integrated Th/U as a function of that measured for Martian zircons. Data are from previous studies. Note the large decoupling between measured and time-integrated Th/U for domains within zircon Z2 from NWA 7533. Measured Th/U are also well outside the common magmatic range, much as what can be seen in Jack Hills zircons. Error bars represent two standard errors on analytical measurements. Corresponding data can be found in Credit: Nature Communications, doi: 10.1038/s41467-019-10382-y Via extensive experiments, Guitreau and Flahaut showed that decoupling between the measured and time-integrated Th/U exhibited by terrestrial zircons as a proxy for zircon alterations by aqueous solutions at low temperatures. Upon comparison, the scientists showed that lunar (moon) zircons exhibited anomalously high Th/U in compliance with the common range for terrestrial larva/magma based igneous (fiery) zircon. This was expected since there is no evidence for liquid water on the moon. Similarly, Martian zircon crystals obtained from the meteorite NWA 7533 and the matrix of NWA 7034 showed consistent measurements and time-integrated Th/U ratios. Based on existing data and the present calculations, Guitreau and Flahaut interpreted the horizontal distribution as evidence for low temperature alterations of Martian zircon grains by aqueous solutions—much like the crystals from Western Australia. The present findings using decoupling between the measured and time-integrated Th/U ratios reinforced the idea of the availability of liquid water in the Martian subsurface. The phenomenon induced advanced weathering of radiation-damaged zircon crystals. Explore further In the present work, Guitreau and Flahaut explored if decoupling between the measured and time-integrated Th/U in Zircon could proxy for low-temperature aqueous alterations and then outlined the principles of their new method. When the scientists applied the method to extraterrestrial zircons on the moon for comparison with Martian zircons, they obtained evidence for low-temperature aqueous weathering on Mars. In this way, Guitreau and Flahaut presented their new data with robust evidence from existing investigations to indicate that the low-temperature alteration event recorded in NWA zircons occurred in the late Amazonian period on Mars. They assume that the availability of water for weathering in the late-Amazonian was likely controlled by impact-induced hydrothermal activity. The observations in the present study were consistent with post-brecciation (rock fragmentation) zircon alteration, and the youngest volcanic activity on Mars could also have played a role due to alterations with the current cryosphere. The recorded alterations of Zircons in the NWA 7533 meteorite represented the youngest episode of persistent aqueous alteration thus far reported on Mars. The results support the concept that Mars may yet be habitable relative to the evidenced availability of liquid water in its recent past. Calculated radiation doses as a function of Th/U in zircon. The panels a, b and c correspond to data from previous studies. Note the general upward-opening fan shape distribution of data above the first percolation point (stage at which amorphous domains become connected). Corresponding data can be found in Credit: Nature Communications, doi: 10.1038/s41467-019-10382-y Many accounts at present support the presence of liquid water on Mars, where hydrated minerals testify to past processes of aqueous weathering in Martian meteorites such as NWA 7533/7034. Planetary scientists aim to estimate the timing of weathering on the Martian crust to help understand its evolution, the availability of liquid water and habitability on Mars. In a recent study, Martin Guitreau and Jessica Flahaut at the University of Manchester, U.K., and the National Center for Scientific Research in France, presented a new method based on U-Th-Pb (Uranium-Thorium-Lead) isotope dating systems. Using the technique, Guitreau and Flahaut investigated if Zircon crystals underwent low-temperature aqueous alteration, similar to observations with Hadean-aged detrital crystals from Western Australia. Results for the two-stage model simulating Martian zircon evolution. Models were run for U enrichment factors of 5 for panels (a) and (b), whereas a factor of 2 was used for the results presented in panels (c) and (d). The pre-alteration Th/U was set to 1 for models shown in panels a and c, and it was set to 0.5 in panels (b) and (d). Th/U ratios increased by alteration were set to 1–27 and 0.5–27, depending on the pre-alteration Th/U. Colored curves correspond to measured Th/U in zircon Z2 domains. The U–Pb resetting age corresponds to the lower intercept of the general Discordia line displayed in a previous study and is represented by a solid vertical line. The horizontal dashed lines, which are the intercepts between the colored curves and the solid vertical line, indicate the time-integrated Th/U deduced from our model. The gray-shaded zones between Th/U values of 1 and 2 correspond to the time-integrated Th/U exhibited by zircon Z2 domains. These results show that time-integrated Th/U derived from the current model are higher than those exhibited by zircon Z2 domains, and, hence, alteration at 1700 Ma (or 1500 Ma) cannot account for the observed decoupling between measured and time-integrated Th/U in the study. Credit: Nature Communications, doi: 10.1038/s41467-019-10382-y More information: Martin Guitreau et al. Record of low-temperature aqueous alteration of Martian zircon during the late Amazonian, Nature Communications (2019). DOI: 10.1038/s41467-019-10382-y A. A. Nemchin et al. Record of the ancient martian hydrosphere and atmosphere preserved in zircon from a martian meteorite, Nature Geoscience (2014). DOI: 10.1038/ngeo2231 Michael H. Carr et al. Geologic history of Mars, Earth and Planetary Science Letters (2009). DOI: 10.1016/j.epsl.2009.06.042 William J. Weber et al. The radiation-induced crystalline-to-amorphous transition in zircon, Journal of Materials Research (2007). DOI: 10.1557/JMR.1994.0688 Timeframe for Martian crust evolution. Displayed are details of knowledge about the history of NWA 7034/7533 and paired stones. The igneous crystallization of NWA7034/7533 zircons and clasts are derived from previous studies. Metamorphism and alteration ages are from additional studies. Brecciation age range is also from previous investigations, and so is the age of ejection. Corresponding data can be found in Credit: Nature Communications, doi: 10.1038/s41467-019-10382-y Moon rock recovered by astronauts likely originated on Earth Journal information: Nature Communications The data for NWA 7533 Zircons showed evidence for aqueous alteration, and modeling the evolving U-Th-Pb isotope system indicated the latest alteration to have occurred in the late Amazonian period (227-56 Ma). The finding largely expands the time duration in which liquid water was available near the Martian surface—suggesting that Mars may still be habitable, based on the evidence. Results of the study are now published on Nature Communications. Zircon is a robust time capsule extensively used in U-Pb geochronology and in the study of magmatic/metamorphic processes on Earth. Planetary scientists have testified this process using terrestrial detrital Zircon predating to 4378 million years. Nevertheless, the alpha-particle emission and α-recoil cascades due to U and Th decay can damage the crystal lattice, causing radiation to accumulate in zirconium at different rates based on the concentrations (ratio) of U and Th. This stage is defined as the “first percolation point” after which chemical elements can be more readily mobilized than in pristine crystals. The progressive amorphization can induce crystal lattice expansion and crack formation in Zircon to enhance the crystal’s sensitivity to thermal events as observed with ancient Zircons from Jack Hills, Western Australia. When they modeled the evolution of the U-Th-Pb isotope systems of zircon to determine the development of decoupling between the measured and time-integrated Th/U, they discovered the alteration occurred at 1500-1700 Ma; as a much younger event. The event corresponded to the late Amazonian period, which is generally considered cold and dry on Mars. As a result, the present work demonstrated the availability of water near the Martian surface in the recent past, suggesting its presence in the present day. To investigate the sensitivity of Zircon, the scientists considered chemical modifications as well as isotopic resetting during preservation of the lattice. To assess these conditions, they used macroscopic visual criteria and microscopic methods including transmission electron microscopy, Raman spectroscopy, X-ray diffraction, nuclear magnetic resonance and atom probe tomography. A simpler, indirect approach is to also calculate the radiation dose that a zircon sample underwent (alpha decay events per gram of sample) using chronological information provided by U-Pb isotype systems and U and Th concentrations. For example, when scientists calculated the radiation doses of Jack Hills zircon datasets, they showed decoupling between the measured and time-integrated Th/U ratios in zircon domains. In this instance, radiation doses appeared to accumulate beyond the first percolation point, however the process required verification prior to its use on aqueous alterations beyond Earth. To understand the timing of Marian aqueous weathering, Guitreau and Flahaut developed a two-stage model of the U-Th-Pb isotope evolution in the present work. They tested if an aberration event (deviation) at 1500 or 1700 Ma could have accounted for the observed decoupling between the measured and time-controlled Th/U and the zircon alteration in NWA 7533. In the first stage of the model, Guitreau and Flahaut investigated zircon formation at 4430 Ma, followed by the second stage as an alteration event on increasing U and Th concentrations to alter zircon in the NWA 7533 meteorite. Using the two-stage model, they showed that uranium could be enriched by 2-5 times the original concentration to match both Jack Hills and Martian Zircon data. The results indicated that the observed levels of Th/U could have occurred at 1700 Ma or 1500 Ma. The scientists further implemented the model with an additional stage to form a three-stage model, using the same Th/U ratios and Uranium enrichment factors as in the two-stage model. The results showed that while the determined alteration ages remained very young, the specific alterations recorded by the scientists occurred during the late Amazonian period. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. , Earth and Planetary Science Letters Citation: Low-temperature aqueous alteration of Martian zircon during the late Amazonian period (2019, June 26) retrieved 18 August 2019 from https://phys.org/news/2019-06-low-temperature-aqueous-martian-zircon-late.html © 2019 Science X Network , Nature Geoscience