This volume aims at providing a platform for sharing valuable topics discussed at the 19th International Symposium on Geodynamics and Earth Tides,23-26 June 2021,Wuhan,China.The complete overview of all nineteen Sympo...This volume aims at providing a platform for sharing valuable topics discussed at the 19th International Symposium on Geodynamics and Earth Tides,23-26 June 2021,Wuhan,China.The complete overview of all nineteen Symposia is found in Table 1,where the times and venues are listed.展开更多
作为EMSLAB电磁感应国际合作计划的一部分,通过对海底观测的三分量变化地磁场的分析,构制了横跨Juan de Fuca洋脊、Juan de Fuca板块到板块俯冲带的三条地磁转换函数剖面,计算了各个测点的地磁场感应矢量。结果表明,Juan de Fuca板块的...作为EMSLAB电磁感应国际合作计划的一部分,通过对海底观测的三分量变化地磁场的分析,构制了横跨Juan de Fuca洋脊、Juan de Fuca板块到板块俯冲带的三条地磁转换函数剖面,计算了各个测点的地磁场感应矢量。结果表明,Juan de Fuca板块的东、西两部分的浅部电性结构是有差异的,近海岸线的东区更导电;而深部电性结构是相对均匀的。这一结果与由大地电磁资料计算得到的二维模型剖面是一致的。展开更多
Coesite was discovered as inclusions in zircon separates from pelitic gneissassociated with a large eclogite body in the North Qaidam ultrahigh-pressure (UHP) terrane. Somegraphite inclusions were also found. This fin...Coesite was discovered as inclusions in zircon separates from pelitic gneissassociated with a large eclogite body in the North Qaidam ultrahigh-pressure (UHP) terrane. Somegraphite inclusions were also found. This finding suggested the occurrence of in-situ UHPmetamorphism and that the terrane was most likely recrystallized at pressures below the diamondstability field. It supported other previous indirect UHP evidence, such as polycrystalline quartzinclusions in eclogitic garnet, quartz lamellae in omphacite and P-T estimates for both eclogite andgarnet peridotite. The U-Pb and Sm-Nd ages of the North Qaidam eclogite indicated that subductionof continental crust occurred in the Early Palaeozoic, which probably recorded a collision betweenthe Sino-Korean and Yangtze plates.展开更多
Bioko Island(3008 m a.s.l) is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porp...Bioko Island(3008 m a.s.l) is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine(83% 〈 Fo 〈 87%) and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase(An62-67Ab35-32Or3-1). Major element variation diagrams show an increase in Si O2, Al2O3, Na2 O and K2 O with increasing Mg O for the studied rock groups. The rocks are characterized by low(^86Sr/^87Sr)i ratios(0.70320e0.70406), high 3Nd(t) values(2.56e4.33) and high(^206Pb/^204Pb)i ratios(20.032e20.035) values.Basalts are enriched in LILE and LREE, and have(Hf/Sm)N= 0.57e1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components.展开更多
A new hierarchical composite consisted of multi-walled carbon nanotubes (CNTs) layer anchored on macroscopic a-A1203 host matrix was synthesized and used as support for Fischer-Tropsch synthesis (FTS). The composi...A new hierarchical composite consisted of multi-walled carbon nanotubes (CNTs) layer anchored on macroscopic a-A1203 host matrix was synthesized and used as support for Fischer-Tropsch synthesis (FTS). The composite constituted by a thin shell of a homogeneous, highly entan-gled and structure-opened carbon nanotubes network and it exhibited a relatively high and fully accessible specific surface area of 76 m2.g-1, compared with that of 5 m2.g-1 of the original a-A1203support. The metal-support interaction between carbon nanotubes surface and cobalt precursor and high effective surface area led to a relatively high dispersion of cobalt nanoparticles. This hierarchically supported cobalt catalyst exhibited a high FTS activity along with an extremely high selectivity towards liquid hydrocarbons compared with the cobalt-based catalyst supported on pristine a-A1203 or on CNTs carriers. This improvement can attribute to the high accessibility of composite surface area com- paring with the macroscopic host structure alone or to the bulk CNTs where the nanoscopic dimension induced a dense packing with low mass transfer which favoured the problem of reactants competitive diffusion towards the cobalt active site. In addition, intrinsic thermal conductivity of decorated CNTs could help the heat dissipating throughout the catalyst body, thus avoiding the formation of local hot spots which appeared in high CO conversion under pure syngas feed in FTS reaction. Cobalt supported on CNTs decorated a-A1203 catalyst also exhibited satisfied high stability during more than 200 h on stream under relatively severe conditions compared with other catalysts reported in the literature. Finally, the macroscopic shape of such composite easily rendered its usage as catalyst support in a fixed-bed configuration without facing problems of transport and pressure drop as encountered with the bulk CNTs.展开更多
We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids...We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.展开更多
We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with po...We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with polynomials of degrees 1 to 9. A significant ~60-yr oscillation is accounted for as soon as degree 4 is reached. This oscillation is even better modeled as a broken line, more precisely a series of ~30-yr long linear segments, with slope breaks (singularities) in ~1904, ~1940, and ~1974 (±3 yr), and a possible recent occurrence at the turn of the 20th century. Oceanic indices PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) have undergone major changes (respectively of sign and slope) roughly at the same times as the temperature slope breaks. This can be interpreted with a system of oceanic non-linear coupled oscillators with abrupt mode shifts. Thus, the Earth’s climate may have entered a new mode (a new ~30-yr episode) near the turn of the 20th century: no further temperature increase, a dominantly negative PDO index and a decreasing AMO index might be expected for the next decade or two.展开更多
Mount Etinde is a Recent (<1 Ma) strombolian-type volcano located on the southern flank of Mount Cameroon. Mount Etinde lavas are distinguished on the basis of the mineralogical compositions of their phenocrysts: o...Mount Etinde is a Recent (<1 Ma) strombolian-type volcano located on the southern flank of Mount Cameroon. Mount Etinde lavas are distinguished on the basis of the mineralogical compositions of their phenocrysts: olivine-pyroxene, olivine-melilite and clinopyroxene-nepheline. Some magnetite and ilmenite occur as inclusions in these early phases. Mafic mineral composition indicates that fractionation involved only limited Fe-enrichment. Oscillatory, normal and sectorial zoning in clinopyroxene relates to the differentiation and fractional crystallization of the magma. Based on the primitive mantle-normalized trace and rare earth element patterns, all nephelinites have high abundances of incompatible elements (103 < La < 281;131 < Ce < 503), with negative anomalies for high field strength element Ti and low Nb/Y (0.1 - 0.2) and Rb/Y (<0.03) ratios, suggesting derivation from a similar source. Textural characteristics and mineral chemical data, as well as whole-rock compositions, suggest that the nephelinitic lavas may have been derived from basaltic magma from a heterogeneous lithospheric mantle. Geochemical modeling of major and trace element variations indicates that the Etinde lavas could not have been produced by only fractional crystallization. Pneumatolytic reaction probably affected the pyromagmas (basaltic magma composition) and was responsible for the nephelinite rocks at lower oxygen fugacity (fO<sub>2</sub>).展开更多
We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^...We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^2 Island is one of the very rare exposures of the Mesozoic accretionary subduction complex along the Chilean margin. Unstable weather, strong winds, steep topography, and very dense vegetation make an on-land mission difficult. Careful preparation based on high-resolution satellite images is advised to optimize shore access and minimize risks of injury. Despite a relatively important degree of regional reequilibration of metamorphic assemblages due to sluggish exhumation through the forearc crust, our results have shown that the island is composed of a nappe stack of ocean-floor derived slivers of metasedimentary units that exhibit very different pressure-temperature-time paths during burial by subduction under the Chilean margin and subsequent exhumation. These rocks are witness to a complex thermal evolution of the subduction zone between Jurassic and Cretaceous times from granulite facies to blueschist facies conditions as well as multiple episodes of accretion at ca. 35 -40 km in depth for almost100 Ma over the Mesozoic era.展开更多
The production of heavy-Havor quark c(c)and b(b)in pp collisions is described under perturbative quantum chromodynamics framework,the extrapolation from hadron-hadron up to nucleus-nucleus collisions is based on geome...The production of heavy-Havor quark c(c)and b(b)in pp collisions is described under perturbative quantum chromodynamics framework,the extrapolation from hadron-hadron up to nucleus-nucleus collisions is based on geometrical model by taking into account the nucleus shadowing effect.We simulate the heavy quark production,the decay to dilepton and effects of detection and analysis technique of the pairs,and predict the muon rate and the invariant mass spectrum of dimuons that could be detected in forward region in Pb-Pb collisions at large hadron collider energies.展开更多
We present a parallel hybrid algorithm based on pseudospectral method (PSM) and finite difference method (FDM) for two-dimensional (2-D) global SH- wavefield simulation. The whole-Earth model is taken as a cross...We present a parallel hybrid algorithm based on pseudospectral method (PSM) and finite difference method (FDM) for two-dimensional (2-D) global SH- wavefield simulation. The whole-Earth model is taken as a cross section of spherical Earth, and corresponding wave equations are defined in 2-D cylindrical coordinates. Spatial derivatives in the wave equations are approximated with efficient and high accuracy PSM in the lateral and high-order FDM in the radial direction on staggered grids. This algorithm allows us to divide the whole-Earth into sub-domains in radial direction and implement efficient parallel computing on PC cluster, while retains high accuracy and efficiency of PSM in lateral direction. A transformation of moment tensor between 3-D spherical Earth and our 2-D model was proposed to give corre- sponding moment tensor components used in 2-D modeling. Comparison of modeling results with those obtained by direct solution method shows very good accuracy of our algorithm. We also demonstrate its feasibility with a lateral heterogeneous whole-Earth model with localized velocity perturbation.展开更多
We report eight new Pb-Pb baddeleyite ages and paleomagnetic results on a series of hitherto unknown Neoarchean NNE-SSW trending mafic dyke swarms intruding the Paleoarchean basement rocks in the
This book consists of papers providing the geology of remote regions covering the boundary areas of Russia,Kazakhstan,Kyrgyzstan,Mongolia and China,which were inaccessible for a long time due to political and logistic...This book consists of papers providing the geology of remote regions covering the boundary areas of Russia,Kazakhstan,Kyrgyzstan,Mongolia and China,which were inaccessible for a long time due to political and logistical reasons.Consequently,these critical regions remained not well integrated in largescale geodynamic models of the Central Asian Orogenic Belt(CAOB).展开更多
Despite representing one of the largest cratons on Earth,the early geological evolution of the Amazonia Craton remains poorly known due to relatively poor exposure and because younger metamorphic and tectonic events h...Despite representing one of the largest cratons on Earth,the early geological evolution of the Amazonia Craton remains poorly known due to relatively poor exposure and because younger metamorphic and tectonic events have obscured initial information.In this study,we investigated the sedimentary archives of the Carajás Basin to unravel the early geological evolution of the southeastern Amazonia Craton.The Carajás Basin contains sedimentary rocks that were deposited throughout a long period spanning more than one billion years from the Mesoarchean to the Paleoproterozoic.The oldest archives preserved in this basin consist of a few ca.3.6 Ga detrital zircon grains showing that the geological roots of the Amazonia Craton were already formed by the Eoarchean.During the Paleoarchean or the early Mesoarchean(<3.1 Ga),the Carajás Basin was large and rigid enough to sustain the formation and preservation of the Rio Novo Group greenstone belt.Later,during the Neoarchean,at ca.2.7 Ga,the southeastern Amazonia Craton witnessed the emplacement of the Parauapebas Large Igneous Province(LIP)that probably covered a large part of the craton and was associated with the deposition of some of the world largest iron formations.The emplacement of this LIP immediately preceded a period of continental extension that formed a rift infilled first by iron formations followed by terrigenous sediments.This major change of sedimentary regime might have been controlled by the regional tectonic evolution of the Amazonia Craton and its emergence above sea-level.During the Paleoproterozoic,at ca.2.1 Ga,the Rio Fresco Group,consisting of terrigenous sediments from the interior of the Amazonia Craton,was deposited in the Carajás Basin.At that time,the Amazonian lithosphere could have either underwent thermal subsidence forming a large intracratonic basin or could have been deformed by long wavelength flexures that induced the formation of basins and swells throughout the craton under the influence of the growing Transamazonian mountain belt.展开更多
Fe(3–x)O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery(LIB). Indeed, Fe(3–x)O4 raspbe...Fe(3–x)O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery(LIB). Indeed, Fe(3–x)O4 raspberry shaped nanostructures consist of original oriented aggregates of Fe(3–x)O4 magnetite nanocrystals, ensuring a low oxidation state of magnetite and a hollow and porous structure, which has been easily combined with graphene sheets. The resulting nanocomposite powder displays a very homogeneous spatial distribution of Fe(3–x)O4 nanostructures at the surface of the graphene sheets. These original nanostructures and their strong interaction with the graphene sheets resulted in very small capacity fading upon Li+ion intercalation. Reversible capacity, as high as 660 m Ah/g, makes this material promising for anode in Li-ion batteries application.展开更多
Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of clima...Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of climate and anthropogenic-induced changes on DOM in riverine systems under increasingly warming conditions still need to be better understood, particularly at large regional scales. To address this knowledge gap, we analyzed a dataset containing 386 published measurements for nine major Chinese river systems, examining dissolved organic carbon (DOC) concentrations and optical properties of chromophoric DOM (CDOM) under diverse envi- ronmental conditions, including mean air temperature, precipitation, surface solar radiation, population density, and land use. Our findings indicate that riverine DOC concentrations are significantly higher in northern China (at ∼46.8%) than in the south. This disparity is primarily due to the high input of soil erosion-induced DOM from drying-affected lands (57.0%), farmland (49.1%), and forests in the north. The high temperate and strong hydrological conditions would lead to DOM degradation easily in the riverine system in the south of China. Our study highlights that various climatic and anthropogenic factors, such as agriculture, vegetation coverage, soil erosion, surface solar radiation, and precipitation, individually or in combination, can affect DOM dynamics in river systems. Therefore, considering alterations in DOM dynamics resulting from climate and environmental changes is crucial for carbon-neutral policies and sustainable river ecosystem assessments.展开更多
基金the IAG:Commission 3,the IAG Sub-commission 3.1,2.6 and International Geodynamics and Earth Tide Service.The Symposium was sponsored by International Association of Geodesy(IAG),Chinese Academy of Sciences,National Natural Science Foundation of China,Innovation Academy for Precision Measurement Science and Technology(APM),State Key Laboratory of Geodesy and Earth's Dynamics,Huazhong University of Science and Technology.We are very grateful to the Scientific Committee,the local organizing committee and all the participants for successfully holding this meeting under the epidemic situation.
文摘This volume aims at providing a platform for sharing valuable topics discussed at the 19th International Symposium on Geodynamics and Earth Tides,23-26 June 2021,Wuhan,China.The complete overview of all nineteen Symposia is found in Table 1,where the times and venues are listed.
文摘作为EMSLAB电磁感应国际合作计划的一部分,通过对海底观测的三分量变化地磁场的分析,构制了横跨Juan de Fuca洋脊、Juan de Fuca板块到板块俯冲带的三条地磁转换函数剖面,计算了各个测点的地磁场感应矢量。结果表明,Juan de Fuca板块的东、西两部分的浅部电性结构是有差异的,近海岸线的东区更导电;而深部电性结构是相对均匀的。这一结果与由大地电磁资料计算得到的二维模型剖面是一致的。
基金the National Natural Science Foundation of China grant 49732070 the Chinese National Key Project for Fundamental Research on the TibetanPlateau(G1998040805).
文摘Coesite was discovered as inclusions in zircon separates from pelitic gneissassociated with a large eclogite body in the North Qaidam ultrahigh-pressure (UHP) terrane. Somegraphite inclusions were also found. This finding suggested the occurrence of in-situ UHPmetamorphism and that the terrane was most likely recrystallized at pressures below the diamondstability field. It supported other previous indirect UHP evidence, such as polycrystalline quartzinclusions in eclogitic garnet, quartz lamellae in omphacite and P-T estimates for both eclogite andgarnet peridotite. The U-Pb and Sm-Nd ages of the North Qaidam eclogite indicated that subductionof continental crust occurred in the Early Palaeozoic, which probably recorded a collision betweenthe Sino-Korean and Yangtze plates.
基金financially supported by the Ministère des Affaires Economiques (Project SGB/ NAT 91-98)
文摘Bioko Island(3008 m a.s.l) is located in the presently more active volcanic zone of the Cameroon Line and composed essentially of alkaline basalts and hawaiites, and lesser mugearites. The rocks show microlitic porphyritic texture with phenocrysts of olivine(83% 〈 Fo 〈 87%) and clinopyroxene in a matrix of plagioclase, clinopyroxene and oxides. Hawaiites and mugearites also include phenocrysts of plagioclase(An62-67Ab35-32Or3-1). Major element variation diagrams show an increase in Si O2, Al2O3, Na2 O and K2 O with increasing Mg O for the studied rock groups. The rocks are characterized by low(^86Sr/^87Sr)i ratios(0.70320e0.70406), high 3Nd(t) values(2.56e4.33) and high(^206Pb/^204Pb)i ratios(20.032e20.035) values.Basalts are enriched in LILE and LREE, and have(Hf/Sm)N= 0.57e1.16. These geochemical signatures are similar to those of the Mount Cameroon rocks, and might be attributed to low degrees of partial melting from a garnet-amphibole-bearing mantle source. The trace elements and isotopic compositions suggest that the parental magma source might have involved HIMU- and EM1-components.
基金the China Scholarship Council (CSC) for the PhD grant during his stay at the LMSPC
文摘A new hierarchical composite consisted of multi-walled carbon nanotubes (CNTs) layer anchored on macroscopic a-A1203 host matrix was synthesized and used as support for Fischer-Tropsch synthesis (FTS). The composite constituted by a thin shell of a homogeneous, highly entan-gled and structure-opened carbon nanotubes network and it exhibited a relatively high and fully accessible specific surface area of 76 m2.g-1, compared with that of 5 m2.g-1 of the original a-A1203support. The metal-support interaction between carbon nanotubes surface and cobalt precursor and high effective surface area led to a relatively high dispersion of cobalt nanoparticles. This hierarchically supported cobalt catalyst exhibited a high FTS activity along with an extremely high selectivity towards liquid hydrocarbons compared with the cobalt-based catalyst supported on pristine a-A1203 or on CNTs carriers. This improvement can attribute to the high accessibility of composite surface area com- paring with the macroscopic host structure alone or to the bulk CNTs where the nanoscopic dimension induced a dense packing with low mass transfer which favoured the problem of reactants competitive diffusion towards the cobalt active site. In addition, intrinsic thermal conductivity of decorated CNTs could help the heat dissipating throughout the catalyst body, thus avoiding the formation of local hot spots which appeared in high CO conversion under pure syngas feed in FTS reaction. Cobalt supported on CNTs decorated a-A1203 catalyst also exhibited satisfied high stability during more than 200 h on stream under relatively severe conditions compared with other catalysts reported in the literature. Finally, the macroscopic shape of such composite easily rendered its usage as catalyst support in a fixed-bed configuration without facing problems of transport and pressure drop as encountered with the bulk CNTs.
基金supported by the National Natural Science Foundation of China(Grants 41374046 and41174034)
文摘We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations.Surface multiples dominate wavefields for shallow event.Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.
基金financial support from IPGP as part of the IEPT RAS-IPGP cooperation.IPGP Contribution NS 3391.
文摘We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with polynomials of degrees 1 to 9. A significant ~60-yr oscillation is accounted for as soon as degree 4 is reached. This oscillation is even better modeled as a broken line, more precisely a series of ~30-yr long linear segments, with slope breaks (singularities) in ~1904, ~1940, and ~1974 (±3 yr), and a possible recent occurrence at the turn of the 20th century. Oceanic indices PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) have undergone major changes (respectively of sign and slope) roughly at the same times as the temperature slope breaks. This can be interpreted with a system of oceanic non-linear coupled oscillators with abrupt mode shifts. Thus, the Earth’s climate may have entered a new mode (a new ~30-yr episode) near the turn of the 20th century: no further temperature increase, a dominantly negative PDO index and a decreasing AMO index might be expected for the next decade or two.
文摘Mount Etinde is a Recent (<1 Ma) strombolian-type volcano located on the southern flank of Mount Cameroon. Mount Etinde lavas are distinguished on the basis of the mineralogical compositions of their phenocrysts: olivine-pyroxene, olivine-melilite and clinopyroxene-nepheline. Some magnetite and ilmenite occur as inclusions in these early phases. Mafic mineral composition indicates that fractionation involved only limited Fe-enrichment. Oscillatory, normal and sectorial zoning in clinopyroxene relates to the differentiation and fractional crystallization of the magma. Based on the primitive mantle-normalized trace and rare earth element patterns, all nephelinites have high abundances of incompatible elements (103 < La < 281;131 < Ce < 503), with negative anomalies for high field strength element Ti and low Nb/Y (0.1 - 0.2) and Rb/Y (<0.03) ratios, suggesting derivation from a similar source. Textural characteristics and mineral chemical data, as well as whole-rock compositions, suggest that the nephelinitic lavas may have been derived from basaltic magma from a heterogeneous lithospheric mantle. Geochemical modeling of major and trace element variations indicates that the Etinde lavas could not have been produced by only fractional crystallization. Pneumatolytic reaction probably affected the pyromagmas (basaltic magma composition) and was responsible for the nephelinite rocks at lower oxygen fugacity (fO<sub>2</sub>).
文摘We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^2 Island is one of the very rare exposures of the Mesozoic accretionary subduction complex along the Chilean margin. Unstable weather, strong winds, steep topography, and very dense vegetation make an on-land mission difficult. Careful preparation based on high-resolution satellite images is advised to optimize shore access and minimize risks of injury. Despite a relatively important degree of regional reequilibration of metamorphic assemblages due to sluggish exhumation through the forearc crust, our results have shown that the island is composed of a nappe stack of ocean-floor derived slivers of metasedimentary units that exhibit very different pressure-temperature-time paths during burial by subduction under the Chilean margin and subsequent exhumation. These rocks are witness to a complex thermal evolution of the subduction zone between Jurassic and Cretaceous times from granulite facies to blueschist facies conditions as well as multiple episodes of accretion at ca. 35 -40 km in depth for almost100 Ma over the Mesozoic era.
基金Supported by the National Basic Research Program of China under Grant No 2007CB815000, the National Natural Science Foundation of China under Grant Nos 10775004, 10975007 and 10975008, China Postdoctoral Science Foundation, and the Young Backbone Teacher Support Program of He'nan Polytechnic University.
基金Supported by the National Natural Science Foundation of China under Grant No.19875019,and Center National de La Recherche Scientique of France.
文摘The production of heavy-Havor quark c(c)and b(b)in pp collisions is described under perturbative quantum chromodynamics framework,the extrapolation from hadron-hadron up to nucleus-nucleus collisions is based on geometrical model by taking into account the nucleus shadowing effect.We simulate the heavy quark production,the decay to dilepton and effects of detection and analysis technique of the pairs,and predict the muon rate and the invariant mass spectrum of dimuons that could be detected in forward region in Pb-Pb collisions at large hadron collider energies.
基金supported by the National Natural Science Foundation of China (Granted Nos.41174034 and 40874020)
文摘We present a parallel hybrid algorithm based on pseudospectral method (PSM) and finite difference method (FDM) for two-dimensional (2-D) global SH- wavefield simulation. The whole-Earth model is taken as a cross section of spherical Earth, and corresponding wave equations are defined in 2-D cylindrical coordinates. Spatial derivatives in the wave equations are approximated with efficient and high accuracy PSM in the lateral and high-order FDM in the radial direction on staggered grids. This algorithm allows us to divide the whole-Earth into sub-domains in radial direction and implement efficient parallel computing on PC cluster, while retains high accuracy and efficiency of PSM in lateral direction. A transformation of moment tensor between 3-D spherical Earth and our 2-D model was proposed to give corre- sponding moment tensor components used in 2-D modeling. Comparison of modeling results with those obtained by direct solution method shows very good accuracy of our algorithm. We also demonstrate its feasibility with a lateral heterogeneous whole-Earth model with localized velocity perturbation.
文摘We report eight new Pb-Pb baddeleyite ages and paleomagnetic results on a series of hitherto unknown Neoarchean NNE-SSW trending mafic dyke swarms intruding the Paleoarchean basement rocks in the
文摘This book consists of papers providing the geology of remote regions covering the boundary areas of Russia,Kazakhstan,Kyrgyzstan,Mongolia and China,which were inaccessible for a long time due to political and logistical reasons.Consequently,these critical regions remained not well integrated in largescale geodynamic models of the Central Asian Orogenic Belt(CAOB).
基金funded by grants of the Fundação AmparoàPesquisa do Estado de São Paulo(FAPESP2015/16235-2,2017/18840-6,2018/02645-2,2018/14617-3,2018/05892-0,2019/17732-0,2019/16066-7 and 2019/12132-5)+2 种基金the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq308045/2013-0 and 307353/2019-2)the Fundação AmparoàPesquisa do Minas Gerais(FAPEMIG project APQ-03793-16)。
文摘Despite representing one of the largest cratons on Earth,the early geological evolution of the Amazonia Craton remains poorly known due to relatively poor exposure and because younger metamorphic and tectonic events have obscured initial information.In this study,we investigated the sedimentary archives of the Carajás Basin to unravel the early geological evolution of the southeastern Amazonia Craton.The Carajás Basin contains sedimentary rocks that were deposited throughout a long period spanning more than one billion years from the Mesoarchean to the Paleoproterozoic.The oldest archives preserved in this basin consist of a few ca.3.6 Ga detrital zircon grains showing that the geological roots of the Amazonia Craton were already formed by the Eoarchean.During the Paleoarchean or the early Mesoarchean(<3.1 Ga),the Carajás Basin was large and rigid enough to sustain the formation and preservation of the Rio Novo Group greenstone belt.Later,during the Neoarchean,at ca.2.7 Ga,the southeastern Amazonia Craton witnessed the emplacement of the Parauapebas Large Igneous Province(LIP)that probably covered a large part of the craton and was associated with the deposition of some of the world largest iron formations.The emplacement of this LIP immediately preceded a period of continental extension that formed a rift infilled first by iron formations followed by terrigenous sediments.This major change of sedimentary regime might have been controlled by the regional tectonic evolution of the Amazonia Craton and its emergence above sea-level.During the Paleoproterozoic,at ca.2.1 Ga,the Rio Fresco Group,consisting of terrigenous sediments from the interior of the Amazonia Craton,was deposited in the Carajás Basin.At that time,the Amazonian lithosphere could have either underwent thermal subsidence forming a large intracratonic basin or could have been deformed by long wavelength flexures that induced the formation of basins and swells throughout the craton under the influence of the growing Transamazonian mountain belt.
基金supported by the funding from the European Research Council(ERCAdvanced Grant,ERC-2011-AdG,Project 291543-IONACES)+2 种基金the Materials Institute Carnot Alsace(MICA)from the Direction Générale de l’Armement(DGA)French-German Research Institute of Saint-Louis(ISL)
文摘Fe(3–x)O4 raspberry shaped nanostructures/graphene nanocomposites were synthesized by a one-step polyol-solvothermal method to be tested as electrode materials for Li-ion battery(LIB). Indeed, Fe(3–x)O4 raspberry shaped nanostructures consist of original oriented aggregates of Fe(3–x)O4 magnetite nanocrystals, ensuring a low oxidation state of magnetite and a hollow and porous structure, which has been easily combined with graphene sheets. The resulting nanocomposite powder displays a very homogeneous spatial distribution of Fe(3–x)O4 nanostructures at the surface of the graphene sheets. These original nanostructures and their strong interaction with the graphene sheets resulted in very small capacity fading upon Li+ion intercalation. Reversible capacity, as high as 660 m Ah/g, makes this material promising for anode in Li-ion batteries application.
基金the National Natural Science Foun-dation of China(Grants No.41925002,42221001,42230509)received financial support from the Haihe Laboratory of Sustainable Chemical Transformations.
文摘Dissolved organic matter (DOM) is closely linked to human activities in drainage basins and plays a crucial role in maintaining ecosystem functioning and reflecting environmental quality. However, the impacts of climate and anthropogenic-induced changes on DOM in riverine systems under increasingly warming conditions still need to be better understood, particularly at large regional scales. To address this knowledge gap, we analyzed a dataset containing 386 published measurements for nine major Chinese river systems, examining dissolved organic carbon (DOC) concentrations and optical properties of chromophoric DOM (CDOM) under diverse envi- ronmental conditions, including mean air temperature, precipitation, surface solar radiation, population density, and land use. Our findings indicate that riverine DOC concentrations are significantly higher in northern China (at ∼46.8%) than in the south. This disparity is primarily due to the high input of soil erosion-induced DOM from drying-affected lands (57.0%), farmland (49.1%), and forests in the north. The high temperate and strong hydrological conditions would lead to DOM degradation easily in the riverine system in the south of China. Our study highlights that various climatic and anthropogenic factors, such as agriculture, vegetation coverage, soil erosion, surface solar radiation, and precipitation, individually or in combination, can affect DOM dynamics in river systems. Therefore, considering alterations in DOM dynamics resulting from climate and environmental changes is crucial for carbon-neutral policies and sustainable river ecosystem assessments.