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新证据表明上下地幔之间相互隔离 快报文章
地球科学快报，2023年第16期
作者:  王晓晨
Microsoft Word(17Kb)  |  收藏  |  浏览/下载：574/0  |  提交时间：2023/08/26
Ti  Earth evolution  
科学家重新确定地球大陆形成时间 快报文章
地球科学快报，2023年第15期
作者:  王晓晨
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Pb isotope  Earth's dynamic evolution  
科学家首次证实地球氧同位素比率取决于地球内部热流 快报文章
地球科学快报，2023年第1期
作者:  张树良
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oxygen isotope ratios  Earth's thermal evolution  heat flow  sedimentary rock  chert  
科学家采用新的联合成像技术分析陨石以探究地球水的来源 快报文章
地球科学快报，2022年第22期
作者:  张树良
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combining neutrons and X-ray imaging  meteorite  Earth evolution  water  
研究首次揭示地球早期微生物对地球轨道周期变化的响应 快报文章
地球科学快报，2022年第21期
作者:  张树良
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microbial community  earth's orbital cycles  orbital driven paleoenvironmental changes  paleoenvironment evolution  
探索地球资源的新测绘技术 快报文章
地球科学快报，2022年第13期
作者:  王晓晨
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Thermochemical structure  Cratonic  Earth evolution  
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：59/0  |  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.


  
Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：34/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.


  
Biological and geophysical feedbacks with fire in the Earth system 期刊论文
ENVIRONMENTAL RESEARCH LETTERS, 2018, 13 (3)
作者:  Archibald, S.;  Lehmann, C. E. R.;  Belcher, C. M.;  Bond, W. J.;  Bradstock, R. A.;  Daniau, A-L;  Dexter, K. G.;  Forrestel, E. J.;  Greve, M.;  He, T.;  Higgins, S. I.;  Hoffmann, W. A.;  Lamont, B. B.;  McGlinn, D. J.;  Moncrieff, G. R.;  Osborne, C. P.;  Pausas, J. G.;  Price, O.;  Ripley, B. S.;  Rogers, B. M.;  Schwilk, D. W.;  Simon, M. F.;  Turetsky, M. R.;  Van der Werf, G. R.;  Zanne, A. E.
收藏  |  浏览/下载：20/0  |  提交时间：2019/04/09
flammability  earth-system feedbacks  niche-construction  evolution  plant traits  vegetation  climate