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Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial 期刊论文
NATURE, 2020, 583 (7817) : 554-+
作者:  T. Blackburn;  G. H. Edwards;  S. Tulaczyk;  M. Scudder;  G. Piccione;  B. Hallet;  N. McLean;  J. C. Zachos;  B. Cheney;  J. T. Babbe
收藏  |  浏览/下载:18/0  |  提交时间:2020/08/09

Uranium isotopes in subglacial precipitates from the Wilkes Basin of the East Antarctic Ice Sheet reveal ice retreat during a warm Pleistocene interglacial period about 400,000 years ago.


Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth'  s past interglacial warm periods(1-3). About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater(2)and sea level was 6 to 13 metres higher(1,3). Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet(3), which has been argued to have remained stable for millions of years before and includes MIS11(4,5). Here we show how the evolution of(234)U enrichment within the subglacial waters of East Antarctica recorded the ice sheet'  s response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of(234)U (the product of rock-water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of(234)U enrichment place the inception of this reservoir at MIS11. Informed by the(234)U cycling observed in the Laurentide Ice Sheet, where(234)U accumulated during periods of ice stability(6)and was flushed to global oceans in response to deglaciation(7), we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The(234)U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines(8-10), indicating(11)that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts(10)and bacteria(12)implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which-assuming current ice volumes-would have contributed about 3 to 4 metres(13)to global sea levels.


  
A remnant planetary core in the hot-Neptune desert 期刊论文
NATURE, 2020, 583 (7814) : 39-+
作者:  David J. Armstrong;  Thé;  o A. Lopez;  Vardan Adibekyan;  Richard A. Booth;  Edward M. Bryant;  Karen A. Collins;  Magali Deleuil;  Alexandre Emsenhuber;  Chelsea X. Huang;  George W. King;  Jorge Lillo-Box;  Jack J. Lissauer;  Elisabeth Matthews;  Olivier Mousis;  Louise D. Nielsen;  Hugh Osborn;  Jon Otegi;  Nuno C. Santos;  ;  rgio G. Sousa;  Keivan G. Stassun;  Dimitri Veras;  Carl Ziegler;  Jack S. Acton;  Jose M. Almenara;  David R. Anderson;  David Barrado;  Susana C. C. Barros;  Daniel Bayliss;  Claudia Belardi;  Francois Bouchy;  ;  sar Briceñ;  o;  Matteo Brogi;  David J. A. Brown;  Matthew R. Burleigh;  Sarah L. Casewell;  Alexander Chaushev;  David R. Ciardi;  Kevin I. Collins;  Knicole D. Coló;  n;  Benjamin F. Cooke;  Ian J. M. Crossfield;  Rodrigo F. Dí;  az;  Elisa Delgado Mena;  Olivier D. S. Demangeon;  Caroline Dorn;  Xavier Dumusque;  Philipp Eigmü;  ller;  Michael Fausnaugh;  Pedro Figueira;  Tianjun Gan;  Siddharth Gandhi;  Samuel Gill;  Erica J. Gonzales;  Michael R. Goad;  Maximilian N. Gü;  nther;  Ravit Helled;  Saeed Hojjatpanah;  Steve B. Howell;  James Jackman;  James S. Jenkins;  Jon M. Jenkins;  Eric L. N. Jensen;  Grant M. Kennedy;  David W. Latham;  Nicholas Law;  Monika Lendl;  Michael Lozovsky;  Andrew W. Mann;  Maximiliano Moyano;  James McCormac;  Farzana Meru;  Christoph Mordasini;  Ares Osborn;  Don Pollacco;  Didier Queloz;  Liam Raynard;  George R. Ricker;  Pamela Rowden;  Alexandre Santerne;  Joshua E. Schlieder;  Sara Seager;  Lizhou Sha;  Thiam-Guan Tan;  Rosanna H. Tilbrook;  Eric Ting;  Sté;  phane Udry;  Roland Vanderspek;  Christopher A. Watson;  Richard G. West;  Paul A. Wilson;  Joshua N. Winn;  Peter Wheatley;  Jesus Noel Villasenor;  Jose I. Vines;  Zhuchang Zhan
收藏  |  浏览/下载:17/0  |  提交时间:2020/07/06

The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune '  desert'  (1,2)(a region in mass-radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b(3), which is thought to have an unusually massive core, and recent discoveries such as LTT9779b(4)and NGTS-4b(5), on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune'  s but an anomalously large mass of39.1-2.6+2.7Earth masses and a density of5.2-0.8+0.7grams per cubic centimetre, similar to Earth'  s. Interior-structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than3.9-0.9+0.8 per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation(6). Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.


Observations of TOI-849b reveal a radius smaller than Neptune'  s but a large mass of about 40 Earth masses, indicating that the planet is the remnant core of a gas giant.


  
Multiple transpolar auroral arcs reveal insight about coupling processes in the Earth's magnetotail 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (28) : 16193-16198
作者:  Zhang, Qing-He;  Zhang, Yong-Liang;  Wang, Chi;  Lockwood, Michael;  Yang, Hui-Gen;  Tang, Bin-Bin;  Xing, Zan-Yang;  Oksavik, Kjellmar;  Lyons, Larry R.;  Ma, Yu-Zhang;  Zong, Qiu-Gang;  Moen, Joran Idar;  Xia, Li-Dong
收藏  |  浏览/下载:14/0  |  提交时间:2020/07/06
aurora  solar-terrestrial interaction  magnetosphere  polar ionosphere  transpolar auroral arcs  
Extreme climate after massive eruption of Alaska's Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (27) : 15443-15449
作者:  McConnell, Joseph R.;  Sigl, Michael;  Plunkett, Gill;  Burke, Andrea;  Kim, Woon Mi;  Raible, Christoph C.;  Wilson, Andrew, I;  Manning, Joseph G.;  Ludlow, Francis;  Chellman, Nathan J.;  Innes, Helen M.;  Yang, Zhen;  Larsen, Jessica F.;  Schaefer, Janet R.;  Kipfstuhl, Sepp;  Mojtabavi, Seyedhamidreza;  Wilhelms, Frank;  Opel, Thomas;  Meyer, Hanno;  Steffensen, Jorgen Peder
收藏  |  浏览/下载:17/0  |  提交时间:2020/06/29
ice core  volcano  Okmok  Rome  climate forcing  
Vertical angular momentum constraint on lunar formation and orbital history 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (27) : 15460-15464
作者:  Tian, ZhenLiang;  Wisdom, Jack
收藏  |  浏览/下载:8/0  |  提交时间:2020/06/29
moon formation  orbital evolution  angular momentum  
The Nd-142/Nd-144 variations in mantle-derived rocks provide constraints on the stirring rate of the mantle from the Hadean to the present 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (26) : 14738-14744
作者:  Hyung, Eugenia;  Jacobsen, Stein B.
收藏  |  浏览/下载:5/0  |  提交时间:2020/06/22
Quantifying uncertainties of climate signals in chemistry climate models related to the 11-year solar cycle - Part 1: Annual mean response in heating rates, temperature, and ozone 期刊论文
ATMOSPHERIC CHEMISTRY AND PHYSICS, 2020, 20 (11) : 6991-7019
作者:  Kunze, Markus;  Kruschke, Tim;  Langematz, Ulrike;  Sinnhuber, Miriam;  Reddmann, Thomas;  Matthes, Katja
收藏  |  浏览/下载:11/0  |  提交时间:2020/06/16
Massive formation of early diagenetic dolomite in the Ediacaran ocean: Constraints on the "dolomite problem" 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 14005-14014
作者:  Chang, Biao;  Li, Chao;  Liu, Deng;  Foster, Ian;  Tripati, Aradhna;  Lloyd, Max K.;  Maradiaga, Ingrid;  Luo, Genming;  An, Zhihui;  She, Zhenbing;  Xie, Shucheng;  Tong, Jinnan;  Huang, Junhua;  Algeo, Thomas J.;  Lyons, Timothy W.;  Immenhauser, Adrian
收藏  |  浏览/下载:17/0  |  提交时间:2020/06/16
Doushantuo Formation  clumped isotope  early diagenesis  carbonate geochemistry  early oceans  
Identification of chondritic krypton and xenon in Yellowstone gases and the timing of terrestrial volatile accretion 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 13997-14004
作者:  Broadley, Michael W.;  Barry, Peter H.;  Bekaert, David V.;  Byrne, David J.;  Caracausi, Antonio;  Ballentine, Christopher J.;  Marty, Bernard
收藏  |  浏览/下载:9/0  |  提交时间:2020/06/16
origin of Earth'  s volatiles  accretion  mantle plume  noble gases  Yellowstone  
Global impact of atmospheric arsenic on health risk: 2005 to 2015 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (25) : 13975-13982
作者:  Zhang, Lei;  Gao, Yang;  Wu, Shiliang;  Zhang, Shaoqing;  Smith, Kirk R.;  Yao, Xiaohong;  Gao, Huiwang
收藏  |  浏览/下载:16/0  |  提交时间:2020/06/16
atmospheric arsenic  GEOS-Chem  cancer risk  noncarcinogenic effect