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新研究阐释地球神秘D层的形成机理 快报文章
地球科学快报,2024年第11期
作者:  王晓晨
Microsoft Word(17Kb)  |  收藏  |  浏览/下载:591/0  |  提交时间:2024/06/10
Earth's D layer  Earth's core-mantle boundary  
地幔运动对于大陆地形的形成具有重要作用 快报文章
地球科学快报,2024年第10期
作者:  王晓晨
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mantle movements  Earth's surface  
美科学家揭示贵金属的地幔富集机制 快报文章
地球科学快报,2023年第20期
作者:  刘学
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Gold  precious metals  Earth's mantle  
科学家发现地球核幔边界存在新构造层 快报文章
地球科学快报,2023年第08期
作者:  王立伟
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Earth's Core-Mantle Boundary  Ultra-low Velocity Zones  
地核和地幔之间的原始3He交换 快报文章
地球科学快报,2022年第07期
作者:  王晓晨
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Earth's Core  Earth's Mantle  Helium-3 Exchange  
新研究揭示大西洋加宽的地质机理 快报文章
地球科学快报,2021年第3期
作者:  王晓晨
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Plate  Mid-ocean ridge  the earth's mantle  
英国利物浦大学新项目将绘制首个地幔4D地图 快报文章
地球科学快报,2020年第11期
作者:  王立伟
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4-D maps  Earth's mantle  
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
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origin of Earth'  s volatiles  accretion  mantle plume  noble gases  Yellowstone  
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.
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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.


  
Ruthenium isotope vestige of Earth's pre-late-veneer mantle preserved in Archaean rocks 期刊论文
NATURE, 2020, 579 (7798) : 240-+
作者:  Abadie, Valerie;  Kim, Sangman M.;  Lejeune, Thomas;  Palanski, Brad A.;  Ernest, Jordan D.;  Tastet, Olivier;  Voisine, Jordan;  Discepolo, Valentina;  Marietta, Eric, V;  Hawash, Mohamed B. F.;  Ciszewski, Cezary;  Bouziat, Romain;  Panigrahi, Kaushik;  Horwath, Irina;  Zurenski, Matthew A.;  Lawrence, Ian;  Dumaine, Anne;  Yotova, Vania;  Grenier, Jean-Christophe;  Murray, Joseph A.;  Khosla, Chaitan;  Barreiro, Luis B.;  Jabri, Bana
收藏  |  浏览/下载:31/0  |  提交时间:2020/05/13

The accretion of volatile-rich material from the outer Solar System represents a crucial prerequisite for Earth to develop oceans and become a habitable planet(1-4). However, the timing of this accretion remains controversial(5-8). It has been proposed that volatile elements were added to Earth by the late accretion of a late veneer consisting of carbonaceous-chondrite-like material after core formation had ceased(6,9,10). This view could not be reconciled with the ruthenium (Ru) isotope composition of carbonaceous chondrites(5,11), which is distinct from that of the modern mantle(12), or of any known meteorite group(5). As a possible solution, Earth'  s pre-late-veneer mantle could already have contained a fraction of Ru that was not fully extracted by core formation(13). The presence of such pre-late-veneer Ru can only be established if its isotope composition is distinct from that of the modern mantle. Here we report the first high-precision, mass-independent Ru isotope compositions for Eoarchaean ultramafic rocks from southwest Greenland, which display a relative Ru-100 excess of 22 parts per million compared with the modern mantle value. This Ru-100 excess indicates that the source of the Eoarchaean rocks already contained a substantial fraction of Ru before the accretion of the late veneer. By 3.7 billion years ago, the mantle beneath southwest Greenland had not yet fully equilibrated with late accreted material. Otherwise, no Ru isotopic difference relative to the modern mantle would be observed. If constraints from other highly siderophile elements besides Ru are also considered(14), the composition of the modern mantle can only be reconciled if the late veneer contained substantial amounts of carbonaceous-chondrite-like materials with their characteristic Ru-100 deficits. These data therefore relax previous constraints on the late veneer and are consistent with volatile-rich material from the outer Solar System being delivered to Earth during late accretion.