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New perspectives on deep carbon cycling

Science China Earth Sciences 2024年第8期67卷 2411-2422页

作者： weidong sun Center of Deep Sea Research Key Laboratory of Ocean Observation and Forecasting Institute of Oceanology Chinese Academy of Sciences Laoshan Laboratory University of Chinese Academy of Sciences

The proto-atmosphere serves as a crucial starting point for the carbon cycle. Estimations based on atmospheric data from Mars and Venus suggest that Earth's proto-atmosphere contained >110 bar of CO2and >2.6 bar of nitrogen. The protoatmosphere had over 1000 bar of water vapor during the magma ocean stage, assuming the proto-ocean had a volume of two oceans of water. During this stage both water and carbon dioxide were in a supercritical state at the magma-atmosphere interface.Intense serpentinization reactions occurred due to rock-water interaction, producing abundant hydrogen. Consequently, nitrogen is reduced to ammonia, and carbon dioxide to methane, forming carbonate simultaneously. The proto-atmosphere dominated by methane, ammonia, and hydrogen formed a significant amount of amino acids through lightning. This process is essential not only to the origin of life, but also to the early carbon-nitrogen cycle on Earth. By the Hadean eon, a large amount of CO2was sequestered as carbonate and organic material. Subsequently, it mainly entered the deep mantle through mantle overturn or subduction. In the mantle transition zone, carbonate undergoes “Redox freezing”, where carbonate is reduced to diamond through oxidation of ferrous iron in the melt. In the lower mantle, Fe2+undergoes disproportionation reactions, forming Fe3+and metallic iron. Among these, Fe3+mainly resides in bridgmanite, thereby increasing the oxygen fugacity of the lower mantle,while metallic iron falls to the Earth's core. The distribution of carbon in the mantle is crucial for deep carbon cycling. The density curves of diamond and mantle peridotite melt intersect at the bottom of the mantle transition zone（about 660 km）. This density crossover leads to the accumulation of diamond during the magma ocean stage. When materials such as subducting slabs enter the lower mantle, compensatory upwelling of lower mantle material occurs. Bridgmanite enters the upper mantle, decomposes, releasing Fe3+ions and oxidizes diamond to carbonate, which under th

关键词： Carbon cycling Proto-atmosphere Amino acids Subduction initiation Passive margin subduction Atmospheric carbon dioxide

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The influence of silica on reaction rates and molecular hydrogen(H_(2))generation during olivine hydrothermal alteration

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Science China Earth Sciences 2024年第1期67卷 222-233页

作者： Ruifang HUANG weidong sun Xing DING Yusheng ZHAO Yibing LI Xiuqi SHANG CAS Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China SUSTech Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China Center of Deep Sea Research Institute of OceanologyChinese Academy of SciencesQingdao 266071China State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Institue of Geology Chinese Academy of Geological SciencesBeijing 100037China

Hydrothermal alteration of olivine greatly influences geodynamics and the recycling of volatiles(such as water and carbon)in subduction zones.Silica is an important component of geological fluids,and its influence on the hydrothermal alteration of olivine remains poorly constrained.In this study,we performed experiments at 300–515℃ and 3.0 kbar(1 bar=10^(5)Pa)by reacting well homogenized mixtures of olivine and silica powders with saline solutions(0.5 mol L^(−1)NaCl).Silica greatly influences the reaction pathways,reaction rates,and molecular hydrogen(H_(2))formation during olivine hydrothermal alteration.In experiments at 300℃ and 3.0 kbar with mixtures of olivine and 10 wt%silica,olivine was replaced by serpentine and talc.The proportions of serpentine and talc were determined according to standard curves based on infrared spectroscopy analyses.Around 6.5%serpentine and 12%talc were produced after an experimental duration of 7 days,which had no change after a longer period(14 days).Compared to the kinetics in silica-free systems,the rates of olivine hydrothermal alteration in experiments with 10 wt%silica are much lower.The overall reaction is:4.5Forsterite+5.5SiO_(2),aq+4H_(2)O=Serpentine+2Talc.With the addition of more silica(20 wt%and 40 wt%),olivine was transformed into talc.The rates of reaction were much faster,e.g.,for experiments with olivine and 20 wt%silica,43%of talc was produced after 14 days,which increased to 77%for experiments with 40 wt%silica over the same period.The overall reaction is:3Forsterite+5SiO_(2),aq+2H_(2)O=2Talc.In experiments at 400–505℃ and 3.0 kbar,the promoting effect of silica on olivine hydrothermal alteration was also observed,which is closely associated with a decrease in Gibbs free energies of olivine hydrothermal alteration.At 300℃ and 3.0 kbar,silica decreased H_(2)formed during olivine hydrothermal alteration by around an order of magnitude,resulting in an increase in oxygen fugacity.Based on measured H_(2),we calibrated oxygen fugacities,ranging from 0.96 to 3.41 log un

关键词： Olivine hydrothermal alteration Silica Serpentinization Hydrogen Serpentine

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近海海底管道阴极保护有效性的评估方法及应用

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腐蚀与防护 2024年第1期45卷 93-98页

作者：孙伟栋管网集团(徐州)管道检验检测有限公司徐州221008

以某在役海底输油管道牺牲阳极阴极保护系统为应用对象,采用室内试验结合数值模拟方法,及海底管道电位实测和牺牲阳极取样测试等方法,获得了海底管道保护电位水平并预估了牺牲阳极寿命。结果表明:牺牲阳极在所处海域的电化学行为与初始... 详细信息

以某在役海底输油管道牺牲阳极阴极保护系统为应用对象,采用室内试验结合数值模拟方法,及海底管道电位实测和牺牲阳极取样测试等方法,获得了海底管道保护电位水平并预估了牺牲阳极寿命。结果表明:牺牲阳极在所处海域的电化学行为与初始设计选值稍有偏差,结合数值模拟结果,牺牲阳极寿命能够满足初始设计要求(35 a),且寿命期内海底管道保护电位达标,管道处于有效保护状态。数值模拟方法结合实际检测对评估海底管道牺牲阳极阴极保护状况具有较好的一致性和互补性。

关键词：海底管道牺牲阳极阴极保护寿命电位分布数值模拟

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Understand china's Development,Keep Faith in Cooperation

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中印对话（英文版） 2022年第3期 4-9页

作者： sun weidong 不详

I hope young friends search for and discover a true,multi-dimensional and comprehensive picture of china,and contribute more wisdom and energy to the friendly and cooperative bonds between China and India.

关键词： comprehensive friendly cooperative

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Toward Closer China-Pakistan Community With Shared Future

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China News Release 2023年第10期 8-12页

作者： sun weidong minister of foreign affairs

A decade ago,Chinese President Xi Jinping successively put forward the vision of a community with a shared future for mankind,the Belt and Road Initiative and the guiding principles for neighborhood diplomacy featuring amity,sincerity,mutual benefit,and inclusiveness.Pakistan,a reliable ally of China,eagerly responded.In 2013,the China-Pakistan Economic Corridor(CPEC)was launched as an important pioneering project of the Belt and Road cooperation.President Xi attaches high importance to the growth of China-Pakistan relations and the construction of the CPEC.

关键词： Pakistan mutual neighborhood

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Theoretical study of thiourea derivatives as chemosensors for fluoride and acetate anions

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Science China Chemistry 2012年第7期55卷 1428-1434页

作者： JIN RuiFa sun weidong College of Chemistry and Chemical Engineering Chifeng UniversityChifeng 024000China

The different interactions between a chemosensor,1-(naphthalen-2-yl)-3-(6-nitrobenzothiazol-2-yl)-thiourea(1),and F-,acetate(AcO-),Cl-,and Br-anions have been investigated theoretically at the B3LYP/6-31+G(d,p) level with the basis set superposition error(BSSE) correction.It was found that the high selectivity of compound 1 for F-can be ascribed to the ability of the anion to deprotonate the N-H fragment of the host sensor,while the chemosensor also has a strong affinity for AcO-by virtue of the formation of a hydrogen-bonded complex.Intramolecular charge transfer(ICT) causes the colorimetric signaling of compound 1 after interaction with F-/AcO-.A study of substituent effects suggested that the O/NH-and O/S-substituted derivatives are also expected to be promising candidates for chromogenic F-/AcO-chemosensors.

关键词：化学传感器硫脲衍生物阴离子醋酸分子内电荷转移取代基效应取代衍生物相互作用

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Feverfew: a scalable coverage-based hybrid overlay for Internet-scale pub/sub networks

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Science China(Information Sciences) 2014年第5期57卷 51-64页

作者： MA XingKong WANG YiJie sun weidong National Key Laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology

The publish/subscribe(pub/sub)paradigm is a popular communication model for data dissemination in large-scale distributed networks.However,scalability comes with a contradiction between the delivery latency and the memory cost.On one hand,constructing a separate overly per topic guarantees real-time dissemination,while the number of node degrees rapidly increases with the number of subscriptions.On the other hand,maintaining a bounded number of connections per node guarantees small memory cost,while each message has to traverse a large number of uninterested nodes before reaching the subscribers.In this paper,we propose Feverfew,a coverage-based hybrid overlay that disseminates messages to all subscribers without uninterested nodes involved in,and increases the average number of node connections slowly with an increase in the number of subscribers and nodes.The major novelty of Feverfew lies in its heuristic coverage mechanism implemented by combining a gossip-based sampling protocol with a probabilistic searching protocol.Based on the practical workload,our experimental results show that Feverfew significantly outperforms existing coverage-based overlay and DHT-based overlay in various dynamic network environments.

关键词： publish/subscribe coverage-based data dissemination topic-based gossip

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Calcium isotopic signatures of depleted mid-ocean ridge basalts from the northeastern Pacific

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Journal of Oceanology and Limnology 2020年第5期38卷 1476-1487页

作者： ZHU Hongli DU Long ZHANG Zhaofeng sun weidong Center of Deep Sea Research Institute of OceanographyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China College of Earth Science and Engineering Shandong University of Science and TechnologyQingdao 266590China State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China University of Chinese Academy of Sciences Beijing 100049China

A number of high-temperature processes(e.g.,melt-rock reactions,metasomatism,partial melting)can produce signifi cant Ca isotopic fractionation and heterogeneity in the mantle,but the mechanism for such fractionation remains obscure.To investigate the eff ect of mantle partial melting on Ca isotopic fractionation,we reported high-precision Ca isotopic compositions of depleted mid-ocean ridge basalts(MORBs)from the East Pacifi c Rise and Ecuador Rift in the northeastern Pacifi c.Theδ44/40 Ca of these MORB samples exhibit a narrow variation from 0.84‰to 0.88‰with an average of 0.85‰±0.03‰,which are similar to those of reported MORBs(0.83‰±0.11‰)and back-arc basin basalts(BABBs,0.80‰±0.08‰)in literature,but are lower than the estimate value for the bulk silicate Earth(BSE,0.94‰±0.05‰).The lowδ44/40 Ca signatures of MORB samples in this study cannot be caused by fractional crystallization,since intermediate-mafi c diff erentiation has been demonstrated having only limited eff ects on Ca isotopic fractionation.Instead,the off set ofδ44/40 Ca between MORBs and the BSE is most likely produced by mantle partial melting.During this process,the light Ca isotopes are preferentially transferred to the melt,while the heavy ones tend to stay in the residue,which is consistent with the fact thatδ44/40 Ca of melt-depleted peridotites increases with partial melting in literature.The behavior of Ca isotopes during mantle partial melting is closely related to the inter-mineral(Cpx and Opx)Ca isotopic fractionation and melting mineral modes.Mantle partial melting is one of the common processes that can induce lowerδ44/40 Ca values in basalts and Ca isotopic heterogeneity in Earth’s mantle.

关键词： Ca isotopes mid-ocean ridge basalts(MORBs) mantle partial melting magma diff erentiation

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Plate convergence in the Indo-Pacific region

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Journal of Oceanology and Limnology 2020年第4期38卷 1008-1017页

作者： sun weidong ZHANG Lipeng LIAO Renqiang sun Saijun LI Congying LIU He Center of Deep Sea Research Institute of OceanologyCenter for Ocean Mega-ScienceChinese Academy of SciencesQingdao 266071China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China University of Chinese Academy of Sciences Beijing 100049China

The Indo-Pacific convergence region is the best target to solve the teo remaining challenges of the plate tectonics theory,i.e.,subduction initiation and the driving force of plate tectonics.Recent studies proposed that the Izu-Bonin subduction initiation belongs to spontaneous initiation,which implies that it started from extension,followed by low angle subduction.Numerical geodynamic modeling suggests that the initiation of plate subduction likely occurred along a transform fault,which put the young spreading ridge in direct contact with old oceanic crust.This,however,does not explain the simultaneous subduction initiation in the west Pacific region in the Cenozoic.Namely,the subduction initiations in the Izu-BoninMariana,the Aleutian,and the Tonga-Kermadec trenches are associated with oceanic crusts of different ages,yet they occurred at roughly the same time,suggesting that they were all triggered by a maj or change in the Pacific plate.Moreover,low angle subduction induces compression rather than extension,which requires external compression forces.Given that the famous Hawaiian-Emperor bending occurred roughly at the same time with the onset of westward subductions in the west Pacific,we propose that these Cenozoic subductions were initiated by the steering of the Pacific plate,which are classified as induced initiation.Induced subduction initiation usually occurs in young ocean basins,forming single-track subduction.The closure s of Neo-Tethys Oceans were likely triggered by plume s in the south,forming northward subductions.Interestingly,the Indian plate kept on moving northward more than 50 Ma after the collision between the Indian and Eurasian continents and the break-off of the subducted oceanic slab attached to it.This strongly suggests that slab pull is not the main driving force of plate tectonics,whereas slab sliding is.

关键词： plate tectonics subduction initiation drifting history Pacific plate Indian plate slab sliding

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Plate subduction, oxygen fugacity, and mineralization

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Journal of Oceanology and Limnology 2020年第1期38卷 64-74页

作者： LIU He LIAO Renqiang ZHANG Lipeng LI Congying sun weidong Key Laboratory of Marine Geology and Environment Center of Deep-Sea ResearchInstitute of OceanologyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Mineral Resources Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and TechnologyQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China

Plate subduction is the largest natural factory that processes elements,which controls recycling and mineralization of a variety of elements.There are three major ore deposit belts in the world:the circumPacific,the centralAsian,and the Tethys belts.All the three belts are closely associated with plate subductions,the mechanism remains obscure.We approached this problem from systematic studies on the behaviours of elements during geologic processes.This contribution summaries the recent progress of our research group.Our results suggest that porphyry Cu deposits form through partial melting of subducted young oceanic crust under oxygen fugacities higher than AFMQ^+1.5,which is promoted after the elevation of atmospheric oxygen at ca.550 Ma.Tin deposits are associated with reducing magmatic rocks formed as a consequence of slab rollback.The Neo-Tethys tectonic regime hosts more than 60%of the world's total Sn reserves.This is due to the reducing environment formed during the subduction of organic rich sediments.For the same reason,porphyry Cu deposits formed in the late stages during the closure of the Neo-Tethys Ocean.Tungsten deposits are also controlled by slab rollback,but is not so sensitive to oxygen fugacity.Subduction related W/Sn deposits are mostly accompanied by abundant accessory fluorites due to the breakdown of phengite and apatite.Decomposition of phengite is also significant for hard rock lithium deposits,whereas orogenic belt resulted from plate subduction promote the formation of Li brine deposits.Cretaceous red bed basins near the Nanling region are favorable for Li brines.Both Mo and Re are enriched in the oxidationreduction cycle during surface processes,and may get further enriched once Mo-,Re-enriched sediments are subducted and involved in magmatism.During plate subduction,Mo and Re fractionate from each other.Molybdenum is mainly hosted in porphyry Mo deposits and to a less extent,porphyry Cu-Mo deposits,whereas Re is predominantly hosted in porphyry Cu-Mo deposits and sedimentary sulfide

关键词： plate subduction oxygen fugacity ore deposits geochemical behaviors subduction factory

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