四川新康风化淋滤型海泡石的热相变研究

以四川新康风化淋滤型海泡石为研究对象，利用X射线衍射分析和红外光谱分析技术，对海泡石的热相变过程及特征进行了研究。结果发现，四川新康风化淋滤型海泡石的相变过程与沉积型、热液型海泡石相变过程明显不同，其相变过程可以划分为两个阶段：800℃以下保持海泡石相；800℃以上海泡石相转化为斜顽辉石相。     

The magmatic to hydrothermal transition and its bearing on ore-forming systems

The exsolution of volatile phases from silicate magmas controls physical and chemical magma properties and influences large-scale geologic phenomena and processes having major societal and economic implications including the release of climate-altering gases to the atmosphere, the explosivity of volcanic eruptions, hydrothermal alteration, and the generation of magmatic–hydrothermal mineralization. These volatile phases exsolve from a wide variety of magmas and cover a very broad spectrum of compositions.

The transition from the orthomagmatic to the hydrothermal stages has important bearing on these fundamentally important geologic phenomena, and this report summarizes the published results of a dozen scientific investigations on the magmatic–hydrothermal transition as applied to volcanic eruption and magmatic–hydrothermal mineralization. These studies involve a variety of analytical and experimental methodologies, and many focus on fluid and melt inclusions from mineralized magmatic systems. A primary goal of each study is to better understand the role of magmatic volatiles and the importance of the magmatic–hydrothermal transition on these geologic processes.     

The structural role of Ti in aluminosilicate liquids in the glass transition range: insights from heat capacity and shear viscosity measurements

The shear viscosities and 1 bar heat capacities of glasses and melts along the 67mol% silica isopleth in the system SiO₂-Al₂O₃-Na₂O-TiO₂ have been determined in the temperature ranges 780-1140 K and 305-1090 K respectively. Anomalous behaviour of both these properties is observed for compositions rich in TiO₂ and/or Al₂O₃, an observation attributed to liquid-liquid phase separation followed by anatase crystallization. For samples which do not show anomalous behaviour, it is found that the partial molar heat capacity of the TiO₂ component previously determined in Al-free compositions reproduces our heat capacities to within 1.3%. Viscosity data show that addition of TiO₂ tends to increase viscosity and melt fragility at constant temperature. Furthermore, heat capacity and viscosity data may be combined within the framework of the Adam-Gibbs theory to extract values of the configurational entropy of the liquids and qualitative estimates of the variation of the average energy barrier to viscous flow. Configurational entropy at 900K is inferred to decrease upon addition of TiO₂, in contrast to previous results from Al-free systems. The compositional limit separating normal from anomalous behaviour, as well as the data for homogenous melts have been used to constrain the structural role of Ti in these samples. Our data are consistent with a majority of Ti in five-fold coordination associated with a titanyl bond, in agreement with previous spectroscopic studies. Furthermore, we find no evidence for a Ti-Al interaction in our samples, and we are led to the conclusion that Al and Ti are incompletely mixed, a hypothesis consistent with the observed reduction of configurational entropy upon addition of TiO₂, suggesting an important role of medium range order in controlling the variations in thermodynamic properties.     

曲靖市冰雹云雷达回波特征及防雹

本文通过对曲靖市711B数字化雷达冰雹云回波特征进行分析,总结2002年～2003年曲靖市防雹工作3年取得的经验,以期提高县级防雹指挥人员雷达回波分析能力和作业指挥能力,在防雹作业中科学的安排防雹炮弹的使用量。     

On the Mechanism of the Locking of the El Nio Event Onset Phase to Boreal Spring

1. Introduction The observed facts show that the ENSO cycle has obvious phase-locking and oscillates irregularly (An and Wang, 2001; Kaplan et al., 1998). Based on Zibiak and Cane's (1987) model (hereafter, the Z-C model) and simple, coupled ocean-atmosph…     

海洋平流的季节变化对La Nia事件成熟位相锁定的作用

用一个中等复杂程度的热带海气耦合模式模拟LaNi na事件成熟位相锁定在年底左右的特征并研究其形成的机制。结果表明 ,模式能很好地模拟观测到的LaNi na事件成熟位相锁定在年底左右的特征。LaNi na事件成熟位相锁定在年底主要由海洋气候基本态引起。海洋垂直平均流是LaNi na事件成熟位相锁定在年底左右的最主要因子。由海洋气候基本态的季节变化所引起的冷平流的季节变化是LaNi na事件成熟位相锁定在年底的机制。在LaNi na事件期间 ,1～ 5月份 ,赤道中东太平洋地区的冷平流较弱 ,它不能平衡海气热量交换过程的影响 ,因而海洋表面温度增加。这一过程使海气耦合不稳定度减弱 ,从而使LaNi na事件衰减。 6～ 12月份 ,赤道中东太平洋地区的冷平流较强。海气热量交换过程的影响不能平衡较强冷平流的影响 ,因而海洋表面温度减小。这一过程使海气耦合不稳定度加强 ,从而使LaNi na事件发展。这样 ,LaNi na事件成熟位相容易出现在年底左右。     

闽东北地区夏季对流云特征的初步分析

利用新一代天气雷达资料分析闽东北地区夏季对流云的回波特征。分析表明:多单体合并对流云在生命史、回波高度、强度、尺度等方面都超过了单体对流云,其液态水总量也更大,自然降水条件和人工影响潜力都优于单体对流云,是夏季降水和人工催化的重要云系。分析得到对流云发展的不同阶段、不同高度层辐合辐散特点,为进一步研究夏季对流云结构和降水原理提供科学依据。通过对两个个例的天气形势分析,指出冷空气对对流发展有一定的激发作用。     

Variation of the plasma turbulence in the central plasma sheet during substorm phases observed by the interball/tail satellite

Fluctuations of the plasma bulk velocity across the plasma sheet are studied using single-point measurements from the Corall instrument on board the Interball/Tail satellite. Several hour-long intervals of continuous data corresponding to quiet geomagnetic conditions and different phases of isolated substorms are analyzed. The plasma sheet flow appears to be strongly turbulent, i.e. dominated by fluctuations that are unpredictable. Corresponding eddy diffusion coefficients were obtained as a function of the autocorrelation time and rms velocity of the fluctuations. It was found that the amplitude of the turbulence and the values of eddy-diffusion coefficients increase significantly during substorm growth and expansion phases and they decrease to their initial level during the recovery phase. We also studied a relationship between the eddy-diffusion coefficients and the absolute value of the geomagnetic field, also measured by the Interball/Tail satellite. It was found that this relationship varies depending on the phase of substorm, indicating possible change in the turbulence regimen with substorm phase.     

Experimental and theoretical study of stability of dense hydrous magnesium silicates in the deep upper mantle

Fluid-undersaturated experiments were conducted to determine the phase relations in the simplified peridotite system MgO-SiO₂-H₂O (MSH) at 11.0-14.5 GPa and 800-1400 °C. Stability relations of dense hydrous magnesium silicates (DHMSs) under fluid-undersaturated conditions were experimentally examined. From the fluid-absent experimental results, we retrieved thermodynamic data for clinohumite, phase A, phase E, and hydrous wadsleyite, consistent with the published data set for dry mantle minerals. With this new data set, we have calculated phase equilibria in the MSH system including dehydration reactions. The dehydration reactions calculated with lower water activities of 0.68-0.60 match the fluid-present experiments of this study above 11.0 GPa and 1000 °C, indicating that considerable amounts of silicate component were dissolved into the fluid phase. The calculated phase equilibria illustrate the stability of the post-antigorite phase A-bearing assemblages. In the cold subducting slab peridotite, phase A + enstatite assemblage survives into the transition zone, whereas phase A + forsterite + enstatite assemblage forms hydrous wadsleyite at a much shallower depth of about 360-km. The slab is subducted with no dehydration reactions occurring when entering the transition zone. The phase equilibria also show the high temperature stability of phase E. Phase E is stable up to 1200 °C at 13.5 GPa, a plausible condition in the mantle of relatively low temperature, i.e., beneath subduction zones. Phase E is a possible water reservoir in the mantle as well as wadsleyite and ringwoodite.