Maastrichtian stratigraphy of Antarctica

first_imgApplication of a strontium isotope stratigaphy to the Late Cretaceous sedimentary succession of Antarctica has provided the impetus for a comprehensive strati-graphical revision of the terminal Maastrichtian Stage. Both the base and top of the stage have been defined by strontium isotope dates, and a series of inter-island correlations within the James Ross Island region (north-eastern Antarctic Peninsula) indicates the presence of a 1150-m-thick sequence of fine-grained clastic sedimentary rocks. A prolific ammonite fauna has been used to define four informal biozones, and a provisional Early-Late Maastrichtian boundary established. Two regional unconformities have been identified within the Antarctic Maastrichtian succession, dated at approximately 70 Ma and 68 Ma, respectivety. Both these stratigraphical hiatuses may be linked to global sea-level regressions, as could the presence of an extremely shallow-Water fauna in the 65.4-65.3 Ma time interval. There is certainly evidence of low shallow-marine palaeotemperatures in the Antarctic Peninsula throughout the Maastrichtian and these three regressions may be glacioeustatic in origin. Antarctic Maastrichtian marine faunas are clearly of comparatively high abundance but low taxonomic diversity. There is evidence of a number of key taxonomic groups being preferentially excluded from the high Southern latitudes through the Campanian-Maastrichtian by the dual controls of low temperature and decreasing water depth. (C) 2004 Elsevier Ltd. All rights reserved.last_img read more

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A new Holocene relative sea level curve for the South Shetland Islands, Antarctica

first_imgPrecise relative sea level (RSL) data are important for inferring regional ice sheet histories, as well as helping to validate numerical models of ice sheet evolution and glacial isostatic adjustment. Here we develop a new RSL curve for Fildes Peninsula, South Shetland Islands (SSIs), a sub-Antarctic archipelago peripheral to the northern Antarctic Peninsula ice sheet, by integrating sedimentary evidence from isolation basins with geomorphological evidence from raised beaches. This combined approach yields not only a Holocene RSL curve, but also the spatial pattern of how RSL change varied across the archipelago. The curve shows a mid-Holocene RSL highstand on Fildes Peninsula at 15.5 m above mean sea level between 8000 and 7000 cal a BP. Subsequently RSL gradually fell as a consequence of isostatic uplift in response to regional deglaciation. We propose that isostatic uplift occurred at a non-steady rate, with a temporary pause in ice retreat ca. 7200 cal a BP, leading to a short-lived RSL rise of ∼1 m and forming a second peak to the mid-Holocene highstand. Two independent approaches were taken to constrain the long-term tectonic uplift rate of the SSIs at 0.22–0.48 m/ka, placing the tectonic contribution to the reconstructed RSL highstand between 1.4 and 2.9 m. Finally, we make comparisons to predictions from three global sea level models.last_img read more

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Internal structure and emplacement mechanism of composite plutons: evidence from Mt Kinabalu, Borneo

first_imgThe internal structure and emplacement mechanisms of composite plutons are investigated using new field data from the composite Late Miocene granitic intrusion of Mt Kinabalu in northern Borneo. The pluton was emplaced in the upper to middle crust in the Late Miocene at the contact between the ultramafic basement and sedimentary cover rocks. Structural data indicate that emplacement occurred during regional NNW–SSE-oriented extension, challenging tectonic models that involve contemporaneous regional compression. The six major units forming the pluton were accommodated by upward flexure of the cover rocks with most magma pulses emplaced successively beneath their predecessors. However, the irregular 3D internal structure of the pluton also reflects preferential emplacement of successive units along the granite–country rock contact of previous units in preference to the basement–cover rock contact exploited by the initial units. This study highlights the complex emplacement mechanisms and internal structure of composite intrusions and assesses how they differ from models of tabular emplacement.last_img read more

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Diapycnal mixing in the Southern Ocean diagnosed using the DIMES tracer and realistic velocity fields

first_imgIn this work, we use realistic isopycnal velocities with a 3D eddy diffusivity to advect and diffuse a tracer in the Antarctic Circumpolar Current, beginning in the Southeast Pacific and progressing through Drake Passage. We prescribe a diapycnal diffusivity which takes one value in the SE Pacific west of 67° W and another value in Drake Passage east of that longitude, and optimise the diffusivities using a cost function to give a best fit to experimental data from the DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) tracer, released near the boundary between the Upper and Lower Circumpolar Deep Water. We find that diapycnal diffusivity is enhanced 20‐fold in Drake Passage compared with the SE Pacific, consistent with previous estimates obtained using a simpler advection‐diffusion model with constant, but different, zonal velocities east and west of 67° W. Our result shows that diapycnal mixing in the ACC plays a significant role in transferring buoyancy within the Meridional Overturning Circulation.last_img read more

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Sex-related differences in the postmolt distribution of Weddell seals (Leptonychotes weddellii ) in the southern Weddell Sea

first_imgThe population of Weddell seals (Leptonychotes weddellii) in the southern Weddell Sea is in a unique position on the continental shelf edge, with vast shelf waters to the south, and deep Southern Ocean to the north. We describe sex-related differences in the winter distribution of this population, from data collected by 20 conductivity-temperature-depth satellite relay data loggers deployed in February 2011 at the end of the annual molt. The regional daily speed was calculated, and a state-space model was used to estimate behavioral states to positions along individuals’ tracks. GLMMs estimated that males and smaller individuals, diving in shallower water, traveled less far per day of deployment (males 14.6 ± 2.26 km/d, females 18.9 ± 2.42 km/d), and males were estimated to dive in shallower water (males 604 ± 382 m, females 1,875 ± 1,458 m). Males and smaller individuals were also estimated to be more resident; males spent an average 83.4% ± 7.7% of their time in a resident behavioral state, compared to females at 74.1% ± 7.1%. This evidence that male and female Weddell seals in the southern Weddell Sea are adopting different strategies has not been shown elsewhere along their circumpolar distribution.last_img read more

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Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

first_imgThe future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further amplify warming.last_img read more

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Pepperdine wins opener 2-0 over BYU

first_img Robert Lovell March 29, 2018 /Sports News – Local Pepperdine wins opener 2-0 over BYU FacebookTwitterLinkedInEmailMALIBU, Calif. (March 25, 2018)—Four different scoring opportunities escaped the grasp of BYU baseball in a 2-0 loss at Pepperdine on Thursday.The Cougars out-hit the Waves 7-4, but stranded runners in scoring position in the third, fifth, seventh and eighth innings. Conversely, BYU forced Pepperdine to leave runners in scoring position in the first, seventh and eighth frames.BYU starter Jordan Wood (2-2) was tagged with the loss after giving up only four hits and a solitary walk in seven plus innings. The Cougars are now 13-11 overall and 2-5 in the West Coast Conference.“Jordan (Wood) was as good today as I’ve seen him, he gave us a great start but we just couldn’t put the offense together for him,” BYU coach Mike Littlewood said. “Wil Jensen did a nice job against us, he didn’t have his best stuff but he got big outs when he needed them, especially when we had bases-loaded no outs in the third.”Consecutive singles by Jarrett Perns, Mitch McIntyre and Brennon Anderson loaded the bases in the third inning for BYU. Perns had extended his consecutive hitting streak to 15 games, but was thrown out at the plate on Daniel Schneemann’s fielder’s choice.The Waves countered with an unearned run in the third and added a second run in the seventh.In the seventh inning, Nate Favero advanced to second after David Clawson successfully executed a sacrifice bunt. Favero moved to third on a passed ball where he remained.Anderson led off with another single in the eighth, advanced to second on a balk, then was thrown out at the plate on Schneemann’s single to left center as the Cougars tried to close the gap on a 2-0 deficit. When Brock Hale drew a walk, the Waves brought in a second relief pitcher with their designated hitter Jordan Qsar and got Keaton Kringlen to fly out with two Cougars aboard.“We hit the ball hard today but the wind held a few of them up,” Littlewood said. “We’ll come back ready play tomorrow (Friday).”Cottonwood High prep Wil Jensen remained undefeated at 5-0 as Pepperdine’s record improved to 11-13 overall and 3-4 in the WCC. The two teams play the second of a three-game series on Friday at 3 p.m. PDT.​ Tags: Baseball/BYU Cougars/WCC Written bylast_img read more

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SUU Football’s Zach Larsen Named As Phil Steele All-American

first_imgJanuary 7, 2019 /Sports News – Local SUU Football’s Zach Larsen Named As Phil Steele All-American Tags: Austin Mikkelson/Chinedu Ahanonu/Judd Cockett/Marquez Tucker/Phil Steele/SUU Football/Zach Larsen Also being honored on Steele’s squad for the Big Sky Conference all-conference team from SUU were offensive lineman Marquez Tucker on the second team offense and linebacker Chinedu Ahanonu on the second team defense. FacebookTwitterLinkedInEmailCEDAR CITY, Utah-Southern Utah football center Zach Larsen was named as a third-team FCS All-American on college football expert Phil Steele’s squads to headline the honors for several Thunderbirds released Monday morning. Prior to this announcement, Larsen, a product of Jordan High School and a Draper native, was named to the Walter Camp FCS All-American team. Making Steele’s third team were tight end McCoy Hill and offensive lineman Austin Mikkelson and linebacker Taylor Nelson made the third team defense. Brad James Written by Additionally, kick returner Judd Cockett was named to the special teams’ second team on Steele’s squad.last_img read more

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Utes Add Transfer QB From Texas

first_img Tags: Cameron Rising/Utah Utes Football FacebookTwitterLinkedInEmail (Salt Lake City, UT)  —  The Utah Utes are adding a quarterback to their team via transfer.  Former Texas quarterback Cameron Rising has committed to the Utes.  Written by January 18, 2019 /Sports News – Local Utes Add Transfer QB From Texascenter_img Associated Press Rising will be eligible to play in 2020. Rising is a freshman who spent this past season as the third-string quarterback for the Longhorns.  last_img

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Pelosi invites US women’s soccer team to Capitol Hill amid uncertainty over Trump invitation

first_img Written by July 8, 2019 /Sports News – National Pelosi invites US women’s soccer team to Capitol Hill amid uncertainty over Trump invitation Beau Lundcenter_img FacebookTwitterLinkedInEmailMaja Hitij/Getty Images(NEW YORK) — President Donald Trump congratulated the U.S. women’s soccer team for their historic World Cup win against the Netherlands on Sunday and tweeted last month that he is planning on inviting the team to the White House, “win or lose.”But amid a public feud with the team’s co-captain and top scorer, Megan Rapinoe, Trump appeared less certain about the invitation when talking to reporters on Sunday.“We haven’t really thought about it,” he said. “We’ll look at that.”The Trump administration has so far hosted only one women’s sports team at the White House — the Baylor University Lady Bears — and has not invited any of the WNBA champions since Trump took office. ABC News has reached out to the White House, but a request for comment was not returned.But House Speaker Nancy Pelosi did not hesitate and tweeted an invitation to the players to visit the U.S. Capitol, tweeting, “I’m pleased to invite the players to the US Capitol as a team or individually to celebrate your inspiring victory.”Pelosi’s invitation comes after Rapinoe, who drew Trump’s ire when she declared last month that she’s “not going to the f—— White House” if her team wins, accepted Democratic Rep. Alexandria Ocasio-Cortez’s offer to visit the Capitol instead.This is not the first time that Pelosi and Democrats have gotten in the middle of one of Trump’s feuds with sports teams and athletes.Last year, Pelosi and Democratic Rep. Barbara Lee — who both represent California — invited the Golden State Warriors and their families to the Capitol amid news that Trump, who withdrew his invitation to the NBA champs in 2017, had decided not to invite them at all after their 2018 win.“I stand by the comments that I made about not wanting to go to the White House, with the exception of the expletive,” Rapinoe said amid some backlash following her initial comments and criticism from Trump. “My mom would be very upset about that.”Rapinoe, who has been an outspoken critic of the Trump administration, was one of the first athletes to follow then-NFL quarterback Colin Kaepernick’s lead in September 2016 by taking a knee during the playing of the national anthem to protest racial oppression and police brutality against black people.Trump slammed Rapinoe on Twitter and claimed that “leagues and teams love coming to the White House,” but since Trump took office, the president has feuded with a wide variety of sports champs — from football to basketball and baseball — and many players refused invitations to the White House, citing their opposition to Trump.“I am a big fan of the American Team, and Women’s Soccer, but Megan should WIN first before she TALKS! Finish the job! We haven’t yet … invited Megan or the team, but I am now inviting the TEAM, win or lose. Megan should never disrespect our Country, the White House, or our Flag, especially since so much has been done for her & the team. Be proud of the Flag that you wear. The USA is doing GREAT!” Trump wrote in a series of tweets.Teammate Ali Krieger, who defended Rapinoe following Trump’s criticism, tweeted that she “will sit this one out as well,” and cited her opposition to the Trump administration’s actions regarding “LGBTQ+ citizens, immigrants & our most vulnerable.”Team forward Alex Morgan said on Friday that the women will decide as a team whether to accept a potential White House invitation.Copyright © 2019, ABC Radio. All rights reserved.last_img read more

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