变质流体对变质反应温度缓冲作用实例研究及意义

有关闽北麻源群、浙西南陈蔡群、冀东麻粒岩和冀西南阜平群变质流体与变质反应温度关系实例研究表明，在变质作用过程中，变质流体对变质反应温度存在着明显的缓冲效应，缓冲的温度范围可超过某些变质相或变质带之间的温度差。因此，变质流体同变质温度、压力一样，是划分变质相带一个独立参数。本文从热力学理论上解释了变质流体对变质反应温度缓冲作用的机制，并对缓冲强度进行了估算，据此阐述了变质流体在变质相带研究中的重要意义。     

硅灰石与盐酸反应模式及产物性质研究

报道了硅灰石与盐酸反应在ＰＨ≥２条件下的反应模式,并从反应产物颗粒形态、粒径分布、表面电位、比表面积等性质及反应动力学规律来证实这种反应模式。     

霞石正长岩烧结反应的热力学分析与实验

霞石正长岩是一种富含K₂O、Al₂O₃、SiO₂的矿产资源。在综合分析云南个旧白云山霞石正长岩物相组成的基础上,对以Na₂CO₃为助剂中温分解霞石正长岩中的铝硅酸盐矿物,提取碳酸钾和氧化铝的技术路线进行了研究。根据热力学理论计算以Na₂CO₃为助剂,主要烧结产物为NaAlSiO₄、KAlSiO₄、Na₂SiO₃时的反应温度,结果表明理论上反应在800 K(527 ℃)左右开始发生。通过烧结反应实验,得到优化反应温度为800～850 ℃,霞石正长岩的分解率达95%以上。X射线衍射分析结果表明,烧结产物的主要物相为NaAlSiO₄、KAlSiO₄和Na₂SiO₃,与热力学计算结果一致。烧结产物的硫酸酸浸实验表明,硅铝分离效果良好,SiO₂、Al₂O₃、K₂O三者的提取率分别高达91.4%、92.2%、92.5%。与前苏联的石灰石烧结法相比,本工艺具有低能耗、低物耗和生产过程清洁高效等优点。     

抽水试验和长观水位联合模拟确定含水层参数

为了更加准确地确定含水层参数,提出了利用地下水流数值模拟软件Modflow耦合大型抽水试验和长观孔水位两个模型的方法,对含水层参数进行了识别与校验。该方法求得的含水层参数避免了只利用抽水试验模型校验所带来的不确定性,同时利用抽水实验数据进行抽水与恢复的全过程曲线拟合,水位降深模拟相对误差小于6%,提高了含水层参数的准确性。     

利用半参数核估计法预报全球电离层总电子含量

本文将半参数平差模型引入电离层球谐函数系数的预报中,建立了半参数球谐函数模型(Semiparametric-Spherical Harmonic,Semi-SH)来预测全球电离层总电子含量.首先,通过快速傅里叶变换获得球谐函数系数的周期和振幅,将振幅高的主周期归入趋势函数,振幅低的剩余周期归入随机信号,建立了半参数模型,同时利用核估计方法拟合趋势函数,解算随机信号,并在时间域上进行外推,得到了预报时间的球谐函数系数,代入15阶电离层球谐函数模型,最后得出电离层总电子含量(Total Electron Content,TEC)的预报值.本文基于欧洲定轨中心(CODE)发布的球谐函数系数进行电离层TEC长期预报和短期预报分析,其中长期预报采用四年预报两年的模式对球谐函数系数进行预报,短期预报设计了三个算例,采用前30天预报后一天的模式,分别预报1天、滑动预报7天和滑动预报30天.实验结果表明:长期预报能够较好地反映全球电离层TEC的变化趋势和波动情况,Semi-SH模型对全球电离层TEC平均值(Mean TEC global,MTEC_global)的拟合值和预报值与M...     

近30年红河三角洲岸线演变

基于1987—2015年Landsat遥感影像,运用ENVI与MapInfo软件提取岸线,分析红河三角洲近30年岸线演变规律,并结合历史岸线、红河多年径流量与输沙量,以及过境该海域多年热带气旋数量等数据,初步探讨红河三角洲岸线演变的影响因素。研究表明红河三角洲岸线在时间上呈前进与后退交替变化特征,其中巴拉特河口以南的岸段以后退为主,河口北部岸段总体以前进为主。巴拉特河口地区淤进与蚀退变化频繁,主要与上游建坝导致入海沙量变化以及台风造成的侵蚀有关。     

Identifying non-stationary and long-term river–aquifer interactions as a response to large climatic patterns and anthropogenic pressures using wavelet analysis (Mancha Oriental Aquifer,Spain)

The objective of this study was to analyse periodicities and the long-term variability of monthly Júcar River–Mancha Oriental Aquifer interactions (RAI) and regionally measured precipitation (PP) with special focus on the correlations between these local hydrological variables and the large climatic patterns governing the Iberian Peninsula, represented by their teleconnection indices – the North Atlantic Oscillation index (NAOi) and the Western Mediterranean Oscillation index (WeMOi). To that end, wavelet analysis has been applied since it not only provides insight into the time-series dynamics but also permits statistical interpretation and correlation analysis. As a result, several periodicities have been detected: intermittent semi-annual periodicity in PP and the NAOi and annual periodicity in the RAI, NAOi and WeMOi time series. Long cycles (approximately 14 years) are also observed in the PP and WeMOi time series. The cross-wavelet spectra show a correlation between the RAI and the rest of the variables on the semi-annual and the annual scales, while wavelet coherence detects common behaviour with longer cycles – 5–6 years between the NAOi and the RAI and cycles of both 1–5 years and 7–10 years between PP and the RAI. Furthermore, results show that the periodicities in the teleconnection indices and precipitation propagate into the RAI with certain lead times: 3 months between the RAI and PP and 6 months between the RAI and the NAOi. The results indicate that the detected periodicities and the coherence between the studied variables could have applications in strategic planning on a river basin scale, taking into account the propagation times and the frequency scale. This methodological approach can be applied into strategic water resource planning independently of the geographical location of the hydrogeological system, the basin size and the climate region.     

The partial equilibration of garnet porphyroblasts in pelitic schists and its control on prograde metamorphism,Glen Roy,Scotland

Garnet porphyroblasts in sillimanite‐bearing pelitic schists contain complex textural and compositional zoning, with considerable variation both within and between adjacent samples. The sillimanite‐bearing schists locally occur in regional Barrovian garnet zone assemblages and are indicative of a persistent lack of equilibrium during prograde metamorphism. Garnet in these Dalradian rocks from the Scottish Highlands preserves evidence of a range of metamorphic responses including initial growth and patchy coupled dissolution–reprecipitation followed by partial dissolution. Individual porphyroblasts each have a unique and variable response to prograde metamorphism and garnet with mainly flat compositional profiles co‐exists with those containing largely unmodified characteristic bell‐shaped Mn profiles. This highlights the need for caution in applying traditional interpretations of effective volume diffusion eliminating compositional variation. Cloudy garnet with abundant fluid inclusions is produced during incomplete modification of the initial porphyroblasts and these porous garnet are then particularly prone to partial replacement in sillimanite‐producing reactions. The modification of garnet via a dissolution–reprecipitation process releases Ca into the effective whole‐rock composition, displacing the pressure–temperature positions of subsequent isograd reactions. This represents the first report of internal metasomatism controlling reaction pathways. The behaviour of garnet highlights the importance of kinetic factors, especially deformation and fluids, in controlling reaction progress and how the resulting variability influences subsequent prograde history. The lack of a consistent metamorphic response, within and between adjacent schists, suggests that on both local and regional scales these rocks have largely not equilibrated at peak metamorphic conditions.     

Nonequilibrium thermodynamic model of manganese carbonate oxidation

Manganese carbonate can be converted to many kinds of manganese oxides when it is aerated in air and oxygen.Pure manganese carbonate can be changed into Mn3O4 and γ-MnOOH,and manganese carbonate ore can be converted to MnO2 under the air-aerating and oxygen-aerating circumstances.The oxidation process of manganese carbonate is a changing process of mineral association,and is also a converting process of valence of manganese itself.Not only equilibrium stat,but also nonequilibrium state are involved in this whole process,This process is an irreversible heterogeneous complex reaction,and oberys the nonequilibrium thermodynamic model,The oxidation rate of manganese cabonate is controlled by many factors,especially nonmanganese metallic ions which play an important role in the oxidation process of manganese carbonate.     

The Dynamical Model of Chemical Oscillaiton in CaF2—HCl—H2O Solid—Liquid Reaction System

Based on the physical chemistry principle ,this paper proposes that the surface adsorption catalytic mechanism of HF is the key to dissolving the oscillation of the CaF2-HCl-H2OL solid-liquid reaction system.Meanwhile the dynamical model of this system has been established in order to study its non-linear dynamical genesis.Although this mathematics model is based on CSTR reaction apparatus,it is applicable to the foliate flow reaction apparatus,too.