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Tectonic evolution of the Pacific margin of Antarctica 2. Structure of Late Cretaceous-early Tertiary plate boundaries in the Bellingshausen Sea from seismic reflection and gravity data

By on May 9, 2021

first_imgInterpretations of multichannel seismic (MCS) reflection and potential field data suggest that some prominent gravity anomalies in the Bellingshausen Sea are associated with plate boundaries that were active during the Late Cretaceous and early Tertiary. Between 83degrees and 93degreesW, a belt of negative anomalies extends along the West Antarctic continental slope, which we term the continental slope gravity anomaly (CSGA). MCS profiles show that the CSGA coincides with an acoustically opaque structural high imaged beneath the lower slope. We interpret this structure as the upper part of an accretionary prism which formed during southward subduction of the Phoenix and Charcot plates, before Chatham Rise separated from West Antarctica. MCS profiles crossing the same margin to the northeast show no evidence of an extensive buried accretionary prism, but instead reveal an abrupt northeastward steepening of the continental slope near 78degreesW. We attribute this change in tectonic style, at least in part, to subduction erosion resulting from subduction of rough oceanic basement which formed at the Antarctic-Phoenix ridge after an abrupt decrease in spreading rate at chron 23r (52 Ma). Near 95degreesW, the Bellingshausen gravity anomaly (BGA) consists of a prominent low-high gravity couple which crosses the West Antarctic continental shelf, slope, and rise. The BGA corresponds to a buried asymmetric basement trough, where Cretaceous oceanic basement dips beneath more elevated basement to the east. The trough probably formed after subduction of Charcot plate ocean floor stalled at the nearby Antarctic Peninsula margin, near the end of the Cretaceous Normal Superchron. Ocean floor to the east of the BGA became attached to the Antarctic Peninsula, and the BGA trough subsequently accommodated a small amount of convergent motion between the Antarctic Peninsula and the ocean floor to the west (initially part of the Marie Byrd Land plate and later part of the Bellingshausen plate). Tectonism probably ceased at the BGAat chron 27 (61 Ma), as a result of a general plate reorganization in the South Pacific.last_img read more

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Divergence time estimates for major cephalopod groups: evidence from multiple genes

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first_imgThis is the first study to use both molecular and fossil data to date the divergence of taxa within the coleoid cephalopods (octopus, squid, cuttlefish). A dataset including sequences from three nuclear and three mitochondrial genes (3415 bp in total) was used to investigate the evolutionary divergences within the group. Divergence time analyses were performed using the Thorne/Kishino method of analysis which allows multiple constraints from the fossil record and permits rates of molecular evolution to vary on different branches of a phylogenetic tree. The data support a Paleozoic origin of the Orders Vampyromorpha, Octopoda and the majority of the extant higher level decapodiform taxa. These estimated divergence times are considerably older than paleontological estimates. The major lineages within the Order Octopoda were estimated to have diverged in the Mesozoic, with a radiation of many taxa around the Cretaceous/Cenozoic boundary. Higher level decapodiform phylogenetic relationships appear to have been obscured due to an ancient diversification of this group.last_img read more

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Antarctica: closer than you think

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first_imgBritish Antarctic Survey director Chris Rapley(above) first conceived the idea of an InternationalPolar Year back in early 2003. It has now growninto the world’s largest coordinated scienceprogramme in 50 years. While IPY will refine ourknowledge of both the Arctic and Antarctic, hereChris explains the importance of Antarctica to thewhole Earth system and why the planet needs IPYnow more than ever.last_img

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Egg-release behaviour in Antarctic krill

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first_imgThe process of egg release is a complex and crucial step in the life cycle of euphausiids, especially with regards mortality and recruitment success. We examined this process in Antarctic krill (Euphausia superba) in terms of the functioning of the female genital apparatus and associated swimming behaviour. A tethering technique combined with video analysis was used to make observations of three females during the release process. We found eggs were steadily extruded over a period of up to 10 h, during which time the krill released between 1,600 and 4,000 eggs and the ovary reduced by a half in length and a third in height. Eggs were mainly released individually or, less commonly, in batches of between 2 and 4 eggs. Release rates were between 5 and 30 eggs min(-1). The steady release of eggs fits well with histological evidence that mature oocytes must pass individually through tight genital ducts with narrow apertures, before coming in to close contact with the sperm plug for fertilisation, and then expulsion from the thelycum as fertilised eggs. During spawning, the female alternated between slow and rapid rates of pleopod beating with egg release occurring at the moment of beat acceleration. At the point of release, the descent of the egg was accelerated through downward beats of the 7th thoracic leg. The cyclic pattern in pleopod beat-rate during spawning may alter swimming performance and contribute to the widely reported sex- and maturity-based biases within krill swarms.last_img read more

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Temporal metabolic rate variation in a continental Antarctic springtail

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first_imgTerrestrial systems in Antarctica are characterized by substantial spatial and temporal variation. However, few studies have addressed the paucity of data on metabolic responses to the unpredictable Antarctic environment, particularly with regard to terrestrial biota. This study measured metabolic rate variation for individual springtails at a continental Antarctic site using a fiber-optic closed respirometry system incorporating a custom-made respiration chamber. Concurrent measures of (behavioural) activity were made via daily pitfall counts. Metabolic rate of Gomphiocephalus hodgsoni measured at constant temperature varied systematically with progression through the austral summer, and was greatest mid-season. This finding of clear intraseasonal and temperature-independent variation in mass-specific metabolic rate in G. hodgsoni is one of very few such reports for a terrestrial invertebrate (and the only such study for Antarctica), and parallels physiological studies in the Antarctic marine environment linking metabolic rate elevation with biological function rather than temperature adaptation per se. However, response to temperature at relatively short time-scales is also likely to be an important part of the life history strategy of Antarctic terrestrial invertebrates such as G. hodgsoni, which appears capable of both physiologically and behaviourally ‘tuning’ in to short-term thermal variability to respond appropriately to the local unpredictable Antarctic habitat. (c) 2008 Elsevier Ltd. All rights reserved.last_img read more

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Koby McEwen Headed To Marquette

By on May 8, 2021

first_img Written by FacebookTwitterLinkedInEmailMILWAUKEE (gomarquette.com)-Per reports from Jeff Goodman of ESPN and Aaron Falk of the Salt Lake Tribune, former Wasatch Academy and Utah State standout Koby McEwen is headed for the Big East.Falk and Goodman report Sunday evening that McEwen will be taking his talents to Milwaukee to play for the Marquette Golden Eagles.In two seasons for the Aggies, McEwen averaged 15 points and 5.2 rebounds a game, while shooting 42.7 percent from the field and 72.6 percent at the foul line.McEwen, a 6’4″ 200-pound guard out of Toronto, averaged 18.95 points and 4.95 rebounds per game for Wasatch Academy as well from 2014-2016 before taking his talents to Logan.McEwen is part of a successful weekend for Marquette, as the Golden Eagles also landed fellow Canadian national Joseph Chartouny, a graudate transfer from Fordham. In three seasons with the Rams, Chartouny averaged 11.9 points and 5 rebounds.A traditional basketball power that won a national title in 1977, Marquette has fallen on hard times of late, having missed the NCAA Tournament in four of the last five seasons. Tags: Koby McEwen/Marquette/Utah State/Wasatch Academy April 22, 2018 /Sports News – Local Koby McEwen Headed To Marquette Brad Jameslast_img read more

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Brito scores 23, leads Utah State past San Jose State

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first_img Written by Tags: Diogo Brito/Mountain West/Utah State Aggies Basketball FacebookTwitterLinkedInEmailSAN JOSE, Calif. (AP) — Diogo Brito scored 23 points with six assists and five rebounds and Utah State defeated San Jose State 81-63 on Wednesday night. Brito, a junior from Portugal, averages 5.6 points per game and had a previous career high of 16 points against Weber State last month. Neemias Queta, a freshman from Portugal, added 14 points with nine rebounds for the Aggies (13-5, 3-2 Mountain West). Associated Presscenter_img Baumann scored 24 points in the first 21½ minutes of play, making six of his first seven 3-point attempts. His sixth 3-pointer drew the Spartans within 43-38 with 18:31 left in the second half. The Spartans’ Zach Chappell hit a 3-pointer a couple of minutes later to make it 43-41 but the Aggies went on a 17-3 run that proved decisive. Once Utah State had its 60-44 lead the Aggies maintained at least a 12-point lead to the finish. January 16, 2019 /Sports News – Local Brito scores 23, leads Utah State past San Jose State Noah Baumann, who averages 8.8 points per game, finished with a career-high 29 points and was 7 of 10 from distance to lead San Jose State (3-13, 0-4) although he went through a 16-minute scoreless stretch in the second half. His previous career high was 23 against Northern Arizona last month.last_img read more

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UVU Baseball Hosts Washington State Tuesday

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first_imgMay 14, 2019 /Sports News – Local UVU Baseball Hosts Washington State Tuesday Tags: A.J. Block/Alexander Marco/Bryce Moyle/Danny Sinatro/Davis Baillie/Dillon Plew/Michael Beltran/Ryan Eastburn/Sacramento State/UVU Baseball/WAC Tournament/Washington State baseball The Cougars are paced by junior outfielder Danny Sinatro (a team-best .291 batting average), and junior infielder Dillon Plew ( a team-best 4 home runs and 27 RBI). Senior infielder Ryan Eastburn leads the Wolverines in batting average (.344) and fellow senior, outfielder Michael Beltran bats .328 and senior infielder Alexander Marco leads Utah Valley with six home runs and 36 RBI. Brad James The Wolverines, despite their disappointing record, took two of three games from conference-leading Sacramento State last week to remain in prime position for claiming a berth in the upcoming WAC tournament at Mesa, Ariz.center_img Written by FacebookTwitterLinkedInEmailOREM, Utah-Tuesday, Utah Valley baseball (13-36, 9-15 in WAC play) hosts Washington State (10-36-1, 2-21-1 in Pac-12 play) in a non-conference tilt at UCCU Ballpark. Junior left-hander A.J. Block (a team-best 39 strikeouts) leads Washington State’s pitching staff. Both sophomore left-hander Bryce Moyle and redshirt junior right-handed hurler Davis Baillie are 1-1 on the season for Washington State in conference play. last_img read more

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Tip Times Announced For Beehive Classic

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first_img Tags: Utah Jazz/Vivint Smart Home Arena/Zions Bank Beehive Classic FacebookTwitterLinkedInEmailSALT LAKE CITY-Monday, the Utah Jazz announced tip times for the third installment of the Zions Bank Beehive Classic, which is slated for December 14 at Vivint Smart Home Arena of Salt Lake City.Weber State will face Utah at 1:00 pm and BYU squares off against Utah State at 5:00 pm.Public ticket sales commence Friday September 13 at 10:00 am through each of the participating schools’ respective athletic department ticket offices, the Vivint Smart Home Arena box office and online at vivintarena.com.Tickets can be purchased separately for each game at $10 for upper bowl seats and $30 for lower bowl seats. September 9, 2019 /Sports News – Local Tip Times Announced For Beehive Classic Written by Brad Jameslast_img read more

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Equinor, YPF partner for exploration of CAN 100 block offshore Argentina

By on May 7, 2021

first_imgThe CAN 100 block, which comprises an area of 15,000km², is considered to be the largest block in the North Argentinian Basin Image: Officials from Equinor and YPF. Photo: courtesy of Ole Jørgen Bratland / Equinor ASA. Equinor has signed an agreement with Argentina’s state-owned YPF to jointly explore the CAN 100 offshore block in the North Argentina Basin.Considered to be the largest block in the North Argentinian Basin, the CAN 100 block comprises an area of 15,000km².Equinor to acquire 50% stake in CAN 100 blockUnder the terms of the preliminary agreement, Equinor has agreed to acquire a 50% stake in the CAN 100 offshore block from YPF.Equinor said that the move will allow the two firms to expand their alliance and move forward with the exploration process offshore Argentinian.Equinor exploration executive vice-president Tim Dodson said: “We are delighted with this opportunity to continue and expand our close partnership with YPF in Argentina.“Currently we are partners in two offshore blocks in the same area, and we are jointly exploring onshore opportunities in the Vaca Muerta formation in the Neuquen province. We are looking forward to collaborate closely with YPF on this new exploration opportunity.“Through this agreement Equinor strengthens its position offshore Argentina, in line with our exploration strategy to access at scale in basins with high impact potential.”YPF acquired a 100% stake in the block in May 2019, following which the first exploratory period of four years started at the block.YPF CEO Daniel González said: “We have a strong relationship with Equinor based on mutual trust built on the development of exploration and unconventional projects. This new agreement deepens our bond with Equinor and allows us to learn from their undisputed experience in offshore projects worldwide.”Currently, Equinor and YPF are partnering on the CAN 102 and CAN 114 blocks which are located in the North Argentina Basin. The blocks were awarded to the partners as part of the open bid round for offshore acreage in Argentina conducted by the national government.In May, the Argentina government awarded permits for hydrocarbon exploration in 18 offshore areas across three basins to companies, including Exxon Mobil, Total, Eni, and Royal Dutch Shell.In 2017, YPF announced plans to invest more than $30bn (£24.7bn) over the next five years to boost its oil and gas production capacity as well as power generation capacity.last_img read more

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