Features of the Formation of Mineral Deposits at the Initial Stages of Formation of the Earth’s Mantle and Crust

The Purpose of the Work: The modern mantle and crust have a complex structure and, in addition, contain both thermal and material heterogeneities, as evidenced by the results of seismic and electromagnetic studies. Changes are also reflected by the change in the mineralogical and chemical composition of the matter. This structure was formed for the long geological history of the planet’s development and the process continues at the present time. The system remains unsteady. To understand the evolution of such dynamic structures, information is needed about the initial state of the system, in our case, about the state of the Earth at the final stage of its formation. It can be obtained only by the results of numerical modeling based on the results of the investigation of the evolution of isotope systems. Therefore, the purpose of the work is to identify the features of the formation of mineral deposits in the early crust and mantle. For this, it is necessary to obtain variants of the numerical solution of the problem of the formation of the planet. Solution Methods: An algorithm for solving a non-linear system of differential equations for solving a 3D boundary dynamic problem in the sphere of an increasing radius is developed. The numerical method of “through account” is used in the work. Results: Based on methods for solving boundary value problems for a system of differential equations with the use of new results of mineralogical and isotope studies of the oldest material samples, quantitative variants of the thermal evolution of the Earth, directly determining the formation of early metallogeny, are constructed. It is shown that the random distribution of particles and bodies of a protoplanetary cloud during the accumulation of the planet causes the formation of a random material and temperature composition of the growing crust and mantle, which ensured a special metallogeny of the cratons and their framing, which no longer repeated in the geological history of the planet. A special role in it was played by changes in the gravitational field during the growth of the planet and the angular velocity of the Earth’s rotation. Further Research: It is proposed to extend the results obtained to the conditions for taking into account the dynamics of the double Earth-Moon system.

Genetic link between saline and carbonatitic mantle fluids:The system NaCl-CaCO_(3)-MgCO_(3)±H_(2)O±Fe^(0) at 6 GPa

Melt inclusions in kimberlitic minerals and diamonds indicate that chlorides are important constituents of mantle carbonatite melts.Besides,alkaline chlorides are important constituents of saline high-density fluids(HDFs)found in diamonds from kimberlites and placers around the world.Continuous compositional variations suggest that saline and carbonatitic HDFs could be genetically linked.However,the essence of this link remains unclear owing to the lack of data on phase relations in the chloridecarbonate systems under pressure.Here we studied subsolidus and melting phase relations in the system NaCl–CaCO_(3)–MgCO_(3)at 6 GPa and 1000–1600℃using a Kawai-type multianvil press.We found that at 1000℃,subsolidus assemblage consists of halite,magnesite,and aragonite.At higher temperatures,the stabilization of dolomite splits the subsolidus area into two partial ternary fields:halite+magnesite+dolomite and halite+dolomite+aragonite.The minimum on the liquidus surface corresponds to the halite-dolomite-aragonite ternary eutectic,situated at 1100℃.The eutectic melt has Ca#89 and contains 30 wt.%Na Cl(26 mol%2NaCl).The system has two ternary peritectics:halite+dolomite=magnesite+liquid located near the ternary eutectic and magnesite+dolomite=Mg-dolomite+liquid situated between 1300 and 1400℃.Although under dry conditions incipient melting yields carbonatedominated melt,the addition of water facilitates the fusion of Na Cl and expands the liquid field to Na Cl-rich compositions with up to 70 wt.%Na Cl.The obtained results favor the idea that hydrous saline melts/fluids(brines)found as inclusions in diamonds could be a lower temperature derivative of mantle carbonatite melts and disagree with the hypothesis on chloride melt generation owing to the chloridecarbonate liquid immiscibility since no such immiscibility was established.We also studied the interaction of the NaCl–CaCO_(3)–MgCO_(3)system with iron metal and found that carbonate reduction produces Cbearing species(Fe^(0),Fe-C melt,Fe_(3)C,Fe_(7)C_(3),C^(0))and wüstite containing Na_(2)O,CaO,and MgO.Besides,a carbonate chloride compound,Ca_(2)Cl_(2)CO_(3),was established among the reaction products.The interaction between Na Cl-bearing carbonate melt shifts its composition toward Mg-poor and Na Cl-rich.Given the above,an alternative hypothesis can be proposed,according to which the interaction of alkaline chloride-bearing carbonate melts formed in the subduction zones with the reduced mantle should be accompanied by diamond crystallization and shift the composition of the melt from carbonatitic to alkali-rich saline.

The core-merging giant impact in Earth's accretion history and its implications

The Earth’s accretion process is accompanied by a large number of collisions.It is widely accepted that collisions dominate the Earth’s late accretion stage.Among all these collisions,there is a special type of collision called Core-merging giant impact(CMGI),in which much or most the impactor’s core merges directly with the protoEarth’s core.This core-merging scenario plays an important role in the Earth’s accretion process and deeply affects the formation of the Earth’s core and mantle.However,because CMGI is a small probability event,it has not been fully studied.Here we use the SPH method to comprehensively study all possible CMGIs in the Earth’s accretion history.We find that CMGI only occurs in the initial conditions with small impact angle,small impact velocity and big impactor.We further discuss the implications of CMGI.We are confident that CMGI inevitably causes the chemical disequilibrium of the Earth’s core and mantle.The CMGI process also brings many light elements into the Earth’s core.In particular,if the Moon-forming giant impact is a CMGI,then CMGI can also explain the abnormal content of HSEs in the Earth’s current mantle.

From Where Did the Water Come That Filled the Earth’s Oceans? A Widely Overlooked Redox Reaction

Though two-thirds of Earth’s surface is covered by oceans, measurements of hydroxyl concentrations in upper mantle minerals, specifically in olivine, reportedly provide surprisingly low values. This has been interpreted to mean that there is little dissolved H2O in the Earth’s mantle. By inference, when Earth formed, there might not have been able enough water to fill the oceans through volcanic degassing. It has therefore been proposed that the missing water was delivered to Earth from space, through comets and other impacting bodies. However, the reported low hydroxyl concentrations in olivine and similar mineralsis probably based on a profound misunderstanding of a solid state reaction that converts hydroxyls into something more difficult to detect. There is indeed a redox reaction that converts, during cooling, solute hydroxyls in the matrix of minerals into peroxy plus H2. This widely overlooked redox conversion takes place under thermodynamic non-equilibrium conditions. Its significance is that any mineral and any rock available for collection at the Earth surface has gone through a process that causes hydroxyls, the telltale sign of dissolved H2O, to change into peroxyplusH2. The H2 molecules are diffusively mobile and may leave even structurally dense mineral grains. The remaining peroxy thus become the memory of the “true” solute H2O content, besides a few residual hydroxyls. Though first described over 30 years ago, this redox conversion has been largely ignored. As a result it is unknown how much H2O is contained in the Earth’s upper mantle but it is certainly much more than has been assumed until now on the basis of analysis of residual hydroxyls.

A Simple Mechanism for Generating a Geomagnetic Field

On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic field were performed, taking into account the speed of its angular rotation, the parameters of density and temperature, the chemical composition, the ionization potential, the dielectric constant and the percentage of the main chemical compounds of the mantle substance.

全球GPS矢量场的分区描述及规律性分析

以平均选择的GPS站点运动年速率编制了全球板块运动矢量场,从而揭示了以下几点规律:1从北大西洋洋脊东侧起,直至西北太平洋岛弧带,欧亚大板块总体呈现顺时针宽弧形运动;2从北大西洋洋脊西侧直至美洲大陆西边缘,北美大板块呈现反时针宽弧形运动;3从南大西洋洋脊东侧起,直至克马德克—新西兰一线,非洲板块和印—澳板块一并呈现从北东指向渐变为北北东指向的运动;4东南太平洋洋脊西侧太平洋板块总体向北西西方向运动;5东南太平洋脊东侧海底大小板块总体向北东东运动;6南美洲整体向北运动;7北极区总体向太平洋北缘运动;南极洲总体向大西洋区运动,并有分裂—对旋迹象。分析上述运动的分区展布,可推论以下几点运动动力学的认识:1拖动全球板块一级运动势态的地幔流可分解为由南极区向北的径向流与由大西洋洋脊和东南太平洋洋脊的东西两侧纬向流的二元动力联合作用,从而造成全球性指向北东和北西的斜向运动;2以重力大地水准面所展现的低阶双重非对称的地球,是引导表壳发育张裂洋脊带和汇聚俯冲带的力学条件;3沿赤道两侧不协调运动带呈现压扭、张扭的复杂变动除了南半球与北半球地幔流在运动指向和速度的差异而造成之外,还可能与地球质心的偏心和南、北半球自转速度的差异变化有关;4南极洲相对环南极洋脊的偏极分流运动还有待进一步研究。在以上认识的基础上,本文讨论了造成三大洋脊在全球表壳的分布、全球深俯冲带仅仅在环太平洋边缘带内发育、北半球和南半球的板块径向、纬向运动有整体性差异等问题的原因。造成上述现象是与地球整体的双重不对称性有关,即北、南半球和0°/180°半球的缩、胀和快、慢的双重非对称,而这种双重不对称性是地球内部物质的热状态、运动状态以及质量分布等原因造成的,我们认为以重力大地水准面所展现的低阶双重非对称的地球表壳,既是约束地幔流的上边界条件,又是引导表壳发育张裂带的力学条件,目前地球表面的这些一级构造因素并不是随意造成的,它们有着深刻的地球物理背景。本文还着重讨论了双重非对称畸形壳体的构造力学背景,根据GPS资料建立了地球热流驱动的地幔经、纬向一级对流格局。

S-wave crustal and upper mantle's velocity structure in the eastern Tibetan Plateau——Deep environment of lower crustal flow

A teleseismic profile consisting of 26 stations was deployed along 30°N latitude in the eastern Tibetan Plateau. By use of the inversion of P-wave receiver function, the S-wave velocity structures at depth from surface to 80 km beneath the profile have been determined. The inversion results reveal that there is significant lateral variation of the crustal structure between the tectonic blocks on the profile. From Linzhi north of the eastern Himalayan Syntaxis, the crust is gradually thickened in NE direction; the crustal thickness reaches to the maximum value (~72 km) at the Bangong-Nujiang suture, and then decreased to 65 km in the Qiangtang block, to 57―64 km in the Bayan Har block, and to 40―45 km in the Sichuan Basin. The eastern segment of the teleseismic profile (to the east of Batang) coincides geographically with the Zhubalong-Zizhong deep seismic sounding profile carried out in 2000, and the S-wave velocity structure determined from receiver functions is consistent with the P-wave velocity structure obtained by deep seismic sounding in respect of the depths of Moho and major crustal interfaces. In the Qiangtang and the Bayan Har blocks, the lower velocity layer is widespread in the lower crust (at depth of 30―60 km) along the profile, while there is a normal velocity distribution in lower crust in the Sichuan Basin. On an average, the crustal velocity ratio (Poisson ratio) in tectonic blocks on the profile is 1.73 (σ = 0.247) in the Lhasa block, 1.78 (σ = 0.269) in the Banggong-Nujiang suture, 1.80 (σ = 0.275) in the Qiangtang block, 1.86 (σ = 0.294) in the Bayan Har blocks, and 1.77 (σ = 0.265) in the Yangtze block, respectively. The Qiangtang and the Bayan Har blocks are characterized by lower S-wave velocity anomaly in lower crust, complicated Moho transition, and higher crustal Poisson ratio, indicating that there is a hot and weak medium in lower crust. These are considered as the deep environment of lower crustal flow in the eastern Tibetan Plateau. Flowage of the ductile material in lower crust may be attributable to the variation of the gravitational potential energy in upper crust from higher on the plateau to lower off plateau.

First-Principles Study of Orthorhombic Perovskites MgSiO3 up to 120 GPa and Its Geophysical Implications

High-pressure behaviour of orthorhombic MgSiO3 perovskite crystal is simulated by using the density functional theory and plane-wave pseudopotentials approach up to 120 GPa pressure at zero temperature. The lattice constants and mass density of the MgSiO3 crystal as functions of pressure are computed, and the corresponding bulk modulus and bulk velocity are evaluated. Our theoretical results agree well with the high-pressure experimental data. A thermodynamic method is introduced to correct the temperature effect on the O-K first-principles results of bulk wave velocity, bulk modulus and mass density in lower mantle PIT range. Taking into account the temperature corrections, the corrected mass density, bulk modulus and bulk wave velocity of MgSiO3-perovskite are estimated from the first-principles results to be 2%, 4%, and 1% lower than the preliminary reference Earth model （PREM） profile, respectively, supporting the possibility of a pure perovskite lower mantle model.

Stony Brook’s Collaborations with Czech Scientists

For the past half-century, I have been fortunate in maintaining collaborations with Czech scientists in the Czech Republic [formerly Czechoslovakia] from the Geofyzikální ústav-GFU [Institute of Geophysics] of the ?eskoslovenská Akademie Věd-?SAV [Czechoslovak Academy of Sciences]. These collaborations have included exchange visits by me to Prague [Praha] and convening international workshops in 1976, 1986 and 1996 in castles used by the ?SAV as well as visits by Czech colleagues to Stony Brook University. The objective of this report is to relate this history. This paper is dedicated to the memory of Vladislav Babu?ka.

My Research Collaborations with Chinese Scientists over the Past Three Decades

For more than three decades, I have been fortunate in working with Chinese graduate students and postdoctoral research scientists in our High-Pressure Laboratory at Stony Brook University. These colleagues have conducted a wide variety of experiments at high pressures and temperatures in collaboration with our other students and researchers. These studies utilized transmission electron microscopy, ultrasonic interferometry, X-ray powder diffraction and synchrotron X-radiation to investigate phase transitions, thermal equations of state, sound velocities, atomic diffusion, dislocation dissociation and deviatoric stress in high-pressure apparatus. During this period, I have also visited high-pressure laboratories in the mainland of China and Taiwan on several occasions. The objective of this paper is to relate this history.

Passive Seismic Deployments from the Lützow-Holm Bay to Inland Plateau of East Antarctica: The Japanese IPY Contribution to Structure and Seismicity

Deployments of seismic stations in Antarctica are an ambitious project to improve the spatial resolution of the Antarctic Plate and surrounding regions. Several international programs had been conducted in wide area of the Antarctic continent during the International Polar Year (IPY 2007-2008). The “Antarctica’s GAmburtsev Province (AGAP)”, the “GAmburtsev Mountain SEISmic experiment (GAMSEIS)” as a part of AGAP, and the “Polar Earth Observing Network (POLENET)” were major contributions to the IPY. The AGAP/GAMSEIS was an internationally coordinated deployments of more than few tens of broadband seismographs over the wide area of East Antarctica. Detailed information on crustal thickness and mantle structure provides key constraints on an origin of the Gamburtsev Mountains;and more broad structure and evolution of the East Antarctic craton and sub-glacial environment. From POLENET data obtained, local and regional signals associated with ice movements were recorded together with a significant number of teleseismic events. Moreover, seismic deployments have been carried out in the Lützow-Holm Bay (LHB), East Antarctica, by Japanese activities. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle, such as the studies by receiver functions suggesting a heterogeneous upper mantle. In addition to studies on the shallow part of the Earth, we place emphasis on these seismic deployments’ ability to image the Earth’s deep interior, as viewed from Antarctica, as a large aperture array in the southern high latitude.

Oxygen isotope fractionation in mantle minerals

The increment method is adopted to calculate oxygen isotope fractionation factors for mantle minerals, particularly for the polymorphic phases of MgSiO3 and Mg2SiO4. The results predict the following sequence of18O-enrichment:pyroxene (Mg, Fe, Ca)2Si2O6>olivine (Mg, Fe)2SiO4 > spinel (Mg, Fe)2SiO4> ilmenite (Mg, Fe, Ca) SiO3>perovskite (Mg, Fe, Ca) SiO3. The calculated fractionations for the calcite-perovskite (CaTiO3) System are in excellent agreement with the experimental calibrations. If there would be complete isotopic equilibration in the mantle, the spinel-structured silicates in the transition zone are predicted to be enriched in18O relative to the perovskite-structured silicates in the lower mantle but depleted in18O relative to olivines and pyroxenes in the upper mantle. The oxygen isotope layering of the mantle might result from differences in the chemical composition and crystal structure of mineral phases at different mantle depths. Assuming isotopic equilibrium on a whole earth scale, the chemical structure of the Earth’s interior can be described by the following sequence of18O-enrichment:upper crust>lower crust>upper mantle>transition zone>lower mantle>core.

从31届地质大会看火成岩石学的研究动向

主要根据第 31届国际地质大会上关于花岗质岩浆作用与成矿 ,花岗岩系统及元古宙岩石圈过程 ,玄武岩 ,碱性侵入体的成因与侵位 ,碳酸岩、金伯利岩、钾镁煌斑岩及相关岩石 ,造山带酸性与中性火山岩 ,火山作用等方面的发言、论文及摘要 ,结合其它资料 ,对近些年来国际、国内火成岩石学领域的新进展和研究动向进行讨论。认为从 2 0世纪末到 2 1世纪初 ,在地球动力学和全球变化的总框架下 ,在人类对资源、环境、减灾重大需求的推动下 ,火成岩石学在地球物质科学、岩石探针、大火成岩省事件与超级地幔柱、地幔动力学。

下地幔矿物研究及其进展

文中综述了20世纪90年代以来对下地幔矿物高温高压研究的进展,详细评论了下地幔温压下(Mg,Fe)SiO3钙钛矿的稳定性、(Mg, Fe)SiO3 钙钛矿和(Mg, Fe)O镁方铁矿的高压状态方程和热弹性及高压熔化、核幔边界温压下铁和硅酸盐的化学反应等几个热点问题;探讨了下地幔的矿物学组成,对下地幔的地震波速异常给出了可能的矿物学解释;介绍了国内同领域的研究工作;展望了下地幔矿物研究的发展方向。

四川牦牛坪稀土矿床地幔流体成矿的碳、氢、氧、硫同位素证据

选取 2种主要矿石类型———碳酸岩伟晶岩型矿石和重晶石伟晶岩型矿石进行了成矿流体的C、H、O、S同位素测试 ,获得δ13 CV PDB值为 - 3.0‰～ - 5 .6‰ ,δDV SMOW 值为 - 5 7‰～ - 88‰ ,δ18OH2 O VSMOW 值为 8.0‰～ 13.3‰ ,δ3 4 SV CDT值为3.3‰～ 5 .9‰ ,以及方解石的δ13 CV PDB值为 - 6 .9‰和δ18OV SMOW 值为 7.3‰～ 7.4‰。所有这些数据表明 。

地球深内部探测及动力学研究

近20年来人类对于地球深内部的探测和认识已经上升到一个新的层次,滋生出许多新的研究热点。一系列最新发现集中于地球深内部研究领域。简述了这一领域研究的成果,探讨其未来发展和研究的方向。

地球内部结构及物性研究的进展及问题

本文对近几年中国地球物理学家在地球内部结构和物质性质方面的研究工作进行总结.从地球内部结构的地震波速度成像,地幔介质的各向异性,地幔间断面及地幔介质物性进行了综述,指出在一些原有的研究领域,工作更加深入,方法更加先进,而且进行了广泛的国际合作,合作的范围也逐渐扩大,方式多样,并开拓了一些新的研究方向.在肯定我们近几年取得的一些新的进展的同时,也提出了地球内部结构研究中应进一步研究的问题.

动高压物理在地球与行星科学研究中的应用

综述了动高压物理应用于地球和行星科学研究中的一些最新进展,包括地球内部的物质组成与热力学状态,巨行星的物质组成模型,太阳系中的碰撞成坑与吸积相互作用等。依据铁的冲击波数据,结合其他热力学数据,可以得到一条统一的铁的熔化曲线,将动高压与静高压数据完全统一,初步解决了长期困扰高压界的动、静压关于铁的熔化温度存在系统偏差的诘难。外推到ICB处(330 GPa),铁的熔化温度(亦称锚定温度)约为(5 950±100) K。冲击Hugoniot 数据,结合地震学模型可以约束地幔与地核的物质组成。冲击压缩下钙钛矿型(Mg0 9,Fe0 1)SiO3的高压声速测量结果表明,1 770 km深度的不连续面不仅是一个相变界面而且是一个化学成分或矿物学分界面。低温可凝聚气体(H2、He)或冰(H2 O, CH4, CO2, NH3 和N2 )的冲击波数据,及Jeffrey 数等其他数据可以用来构建巨行星(如木星和土星)的物质组成模型。地球深部矿物的冲击温度测量可以用来研究它们的高压熔化行为,据此建立的高压相图可以为控制地幔对流的地幔物质的准静态蠕变提供约束条件。熔融硅酸盐在上地幔压力条件下的冲击压缩数据,可以约束地幔熔岩稳定存在的深度,在此深度地幔熔岩不会因固体围岩提供的浮力而向上运移到地表,从而在此深度形成稳定的低速带。冲击波数据在描写行?

低热层大气探测立方星翱翔一号轨道寿命分析

西北工业大学翱翔一号作为欧盟第七框架协议-QB50立方星网络大气探测项目中50颗立方星中的一员，将通过搭载多种大气传感器实现对于低热层大气中性粒子、带电离子、大气阻力参数等的全面探测。对翱翔一号在低热层飞行过程中影响其轨道寿命的主要因素进行分析，并针对不同的发射月份采取多种大气模型进行了分析与仿真，通过仿真可以看出同一个月内发射，当采用不同大气模型时轨道的寿命具有差异。采用同一大气模型，在不同的月份进行发射，立方星的在轨天数也不同，大约在90～120天之间。由于QB50项目中50颗立方星质量相近，轨道高度、轨道倾角相同，因此，文中的研究工作对整个卫星网络的在轨时间估计、任务规划、对各卫星再入返回时间估计分析有重要借鉴意义。

平极长期漂移与地球平均下地幔黏性估计

利用 9个国际纬度观测站的平纬长期变化序列 ,重新讨论并估计了平极的长期漂移 ,得到漂移的平均速率为 (3 .3 5 6″± 0 .1 42″)× 1 0 - 3/a,方向为西经 78.7°± 2 .5° .进一步基于最新的ICE 4G冰期后地壳反弹模型 ,采用地球上 8个冰盖的冰融参数 ,估计了理论的平极长期漂移方向为西经 74.8°.由观测的平极长期漂移速率为约束 ,基于 1 0 6 6B地球模型 ,估计得到地球平均下地幔的黏性为νLM=(0 .5— 1 .7)× 1 0 2 2 Pa·s,表明νLM应具有近 1 0 2 2 Pa·s量级 ,并认为地球平极的长期漂移很可能是由最近的 2 1 0 0