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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：21/0  |  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.


  
The Mesoproterozoic Baoban Complex, South China: A missing fragment of western Laurentian lithosphere 期刊论文
GEOLOGICAL SOCIETY OF AMERICA BULLETIN, 2020, 132 (7-8) : 1404-1418
作者:  Xu, Ya-Jun;  Cawood, Peter A.;  Zhang, Hang-Chuan;  Zi, Jian-Wei;  Zhou, Jin-Bo;  Li, Li-Xing;  Du, Yuan-Sheng
收藏  |  浏览/下载：15/0  |  提交时间：2020/08/18
A giant soft-shelled egg from the Late Cretaceous of Antarctica 期刊论文
NATURE, 2020
作者:  Lewnard, Joseph A.;  Lo, Nathan C.;  Arinaminpathy, Nimalan;  Frost, Isabel;  Laxminarayan, Ramanan
收藏  |  浏览/下载：16/0  |  提交时间：2020/06/22

Egg size and structure reflect important constraints on the reproductive and life-history characteristics of vertebrates(1). More than two-thirds of all extant amniotes lay eggs(2). During the Mesozoic era (around 250 million to 65 million years ago), body sizes reached extremes  nevertheless, the largest known egg belongs to the only recently extinct elephant bird(3), which was roughly 66 million years younger than the last nonavian dinosaurs and giant marine reptiles. Here we report a new type of egg discovered in nearshore marine deposits from the Late Cretaceous period (roughly 68 million years ago) of Antarctica. It exceeds all nonavian dinosaur eggs in volume and differs from them in structure. Although the elephant bird egg is slightly larger, its eggshell is roughly five times thicker and shows a substantial prismatic layer and complex pore structure(4). By contrast, the new fossil, visibly collapsed and folded, presents a thin eggshell with a layered structure that lacks a prismatic layer and distinct pores, and is similar to that of most extant lizards and snakes (Lepidosauria)(5). The identity of the animal that laid the egg is unknown, but these preserved morphologies are consistent with the skeletal remains of mosasaurs (large marine lepidosaurs) found nearby. They are not consistent with described morphologies of dinosaur eggs of a similar size class. Phylogenetic analyses of traits for 259 lepidosaur species plus outgroups suggest that the egg belonged to an individual that was at least 7 metres long, hypothesized to be a giant marine reptile, all clades of which have previously been proposed to show live birth(6). Such a large egg with a relatively thin eggshell may reflect derived constraints associated with body shape, reproductive investment linked with gigantism, and lepidosaurian viviparity, in which a '  vestigial'  egg is laid and hatches immediately(7).


A fossil egg unearthed from Cretaceous deposits in Antarctica is more than 20 cm long, exceeds all known nonavian eggs in volume, is soft-shelled, and was perhaps laid by a giant marine lizard such as a mosasaur.


  
Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica - Part 1: long-term trends 期刊论文
ATMOSPHERIC CHEMISTRY AND PHYSICS, 2020, 20 (11) : 6379-6394
作者:  French, W. John R.;  Mulligan, Frank J.;  Klekociuk, Andrew R.
收藏  |  浏览/下载：12/0  |  提交时间：2020/06/09
Airborne bacteria confirm the pristine nature of the Southern Ocean boundary layer 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (24) : 13275-13282
作者:  Uetake, Jun;  Hill, Thomas C. J.;  Moore, Kathryn A.;  DeMott, Paul J.;  Protat, Alain;  Kreidenweis, Sonia M.
收藏  |  浏览/下载：11/0  |  提交时间：2020/06/09
bioaerosol  marine aerosol  Southern Ocean  
Solar UV radiation measurements in Marambio, Antarctica, during years 2017-2019 期刊论文
ATMOSPHERIC CHEMISTRY AND PHYSICS, 2020, 20 (10) : 6037-6054
作者:  Aun, Margit;  Lakkala, Kaisa;  Sanchez, Ricardo Daniel;  Asmi, Eija;  Nollas, Fernando;  Meinander, Outi;  Sogacheva, Larisa;  De Bock, Veerle;  Arola, Antti;  de Leeuw, Gerrit;  Aaltonen, Veijo;  Bolsee, David;  Cizkova, Klara M.;  Mangold, Alexander;  Metelka, Ladislav;  Jakobson, Erko;  Svendby, T. M.;  Gillotay, Didier;  Van Opstal, Bert
收藏  |  浏览/下载：12/0  |  提交时间：2020/07/02
Deposition, recycling, and archival of nitrate stable isotopes between the air-snow interface: comparison between Dronning Maud Land and Dome C, Antarctica 期刊论文
ATMOSPHERIC CHEMISTRY AND PHYSICS, 2020, 20 (9) : 5861-5885
作者:  Winton, V. Holly L.;  Ming, Alison;  Caillon, Nicolas;  Hauge, Lisa;  Jones, Anna;  Savarino, Joel;  Yang, Xin;  Frey, Markus M.
收藏  |  浏览/下载：11/0  |  提交时间：2020/05/20
Characteristics of methanesulfonic acid, non-sea-salt sulfate and organic carbon aerosols over the Amundsen Sea, Antarctica 期刊论文
ATMOSPHERIC CHEMISTRY AND PHYSICS, 2020, 20 (9) : 5405-5424
作者:  Jung, Jinyoung;  Hong, Sang-Bum;  Chen, Meilian;  Hur, Jin;  Jiao, Liping;  Lee, Youngju;  Park, Keyhong;  Hahm, Doshik;  Choi, Jung-Ok;  Yang, Eun Jin;  Park, Jisoo;  Kim, Tae-Wan;  Lee, SangHoon
收藏  |  浏览/下载：11/0  |  提交时间：2020/05/13
Butcher Ridge igneous complex: A glassy layered silicic magma distribution center in the Ferrar large igneous province, Antarctica 期刊论文
GEOLOGICAL SOCIETY OF AMERICA BULLETIN, 2020, 132 (5-6) : 1201-1216
作者:  Nelson, Demian A.;  Cottle, John M.;  Schoene, Blair
收藏  |  浏览/下载：7/0  |  提交时间：2020/07/02
Extreme thermal metamorphism associated with Gondwana assembly: Evidence from sapphirine-bearing granulites of Rajapalayam, southern India 期刊论文
GEOLOGICAL SOCIETY OF AMERICA BULLETIN, 2020, 132 (5-6) : 1013-1030
作者:  Li, Shan-Shan;  Palin, Richard M.;  Santosh, M.;  Shajis, E.;  Tsunogae, T.
收藏  |  浏览/下载：6/0  |  提交时间：2020/07/02