奉节脐橙种植区土壤地球化学特征

在奉节脐橙种植区野外采集表层土壤样进行分析,探讨了土壤中常量元素、主要微量元素及其有效态的地球化学特征。表层土壤中,主要营养指标N、P、Corg含量较高,K含量一般;微量元素Fe、Zn、B分布较均匀,Mn、Mo分布不太均匀,Cu分布不均匀;土壤元素有效态中,有效态P、Mn、Cu、Si、K、Fe含量丰富。     

前言——我们的共同记忆与理想

2007-08-28 是中国科学院暨香港中文大学地球信息科学联合实验室成立10周年的纪念日,曾经在实验室学习与工作过的学生与学者从国内外回到香港中文大学未圆湖畔,报告自己的研究进展,以学术研讨会的形式展现我们的共同记忆与理想.专栏收集的论文是研讨会中的部分报告,以此形成我们10周年纪念的成果之一.     

Chemo- and Biostratigraphy of the Jurassic Oil Shales from the Qiangtang Basin, Northern Tibet, China: A Case Study of the Toarcian Oceanic Anoxic Event

The marine oil shales of the Qiangtang Basin, northern Tibet, exposed in the Biluo Co, Tuonamu, Shenglihe and Changsheshan areas are believed to be important petroleum source rocks. This work comprehensively analyzed the carbon isotopes, trace elements, and calcareous nannofosills, ammonites and bivalves of the Biluo Co section in the Qiangtang Basin. The organic carbon isotopes show a positive excursion close to 2.17‰(relative to PDB), which, albeit significantly smaller, may also be associated with other Early Toarcian Oceanic Anoxic Events(T-OAE) in the European epicontinental seas and the Tethyan continental margins. Coinciding with the Early Toarcian transgression, the oxygen deficiency in bottom water had led to dysoxic-anoxic conditions and deposition of black shales lacking benthic fauna. Under such condition, the redox-sensitive trace metals such as Mo, V, Ni, Cr, and U were enriched, in conjunction with high planktonic productivity of Watznaueriaceae calcareous nannofossils. Comparison of the results with the records of chemo-and biostratigraphy, as well as the palaeogeography during the Early Jurassic suggests that the anoxia linked to the Early Toarcian oceanic anoxic event was mainly caused by the high surface water temperature, sea-level rise and an increase of surface water productivity.     

西藏扎囊县朗达铜矿地质特征及找矿前景初探①

朗达铜矿处于雅鲁藏布江弧―陆碰撞结合带的北侧、冈底斯陆缘火山―岩浆弧南缘,属于贡嘎―加查EW向铜多金属成矿带;产于喜山期中酸性岩浆岩的断裂带中。目前发现的2条矿(化)带呈脉状、透镜状、似层状产出,且受矿区近EW向或NWW向的断裂控制。矿石构造主要以条带状、脉状及角砾状为主,部分聚合体为斑杂状或浸染状。通过对矿区地质、矿体及矿石特征仔细分析后,认为该矿床主要受构造、岩浆热液控制,且具备良好的找矿前景。     

Numerical examination of the factors controlling DNAPL migration through a single fracture

The migration of five dense nonaqueous phase liquids (DNAPLs) through a single fracture in a clay aquitard was numerically simulated with the use of a compositional simulator. The effects of fracture aperture, fracture dip, matrix porosity, and matrix organic carbon content on the migration of chlorobenzene, 1,2-dichloroethylene, trichloroethylene, tetra-chloroethylene, and 1,2-dibromoethane were examined. Boundary conditions were chosen such that DNAPL entry into the system was allowed to vary according to the stresses applied. The aperture is the most important factor of those studied controlling the migration rate of DNAPL through a single fracture embedded in a clay matrix. Loss of mass to the matrix through diffusion does not significantly retard the migration rate of the DNAPL, particularly in larger aperture fractures (e.g., 50 microm). With time, the ratio of diffusive loss to the matrix to DNAPL flux into the fracture approaches an asymptotic value lower than unity. The implication is that matrix diffusion cannot arrest the migration of DNAPL in a single fracture. The complex relationships between density, viscosity, and solubility that, to some extent, govern the migration of DNAPL through these systems prevent accurate predictions without the use of numerical models. The contamination potential of the migrating DNAPL is significantly increased through the transfer of mass to the matrix. The occurrence of opposite concentration gradients within the matrix can cause dissolved phase contamination to exist in the system for more than 1000 years after the DNAPL has been completely removed from the fracture.     

藏南雅拉香波穹窿角闪片岩的年代学、地球化学及地质意义

雅拉香波穹隆位于特提斯喜马拉雅构造带东部,其拆离系地层为曲德贡岩组,主要由千枚岩、片岩、变粒岩及少量片麻岩组成,通常认为其沉积时代为古生代。本文通过详细的野外工作,在其中新发现的一套与石榴子石绢云千枚岩互层产出的角闪片岩,薄片鉴定主要组成矿物为角闪石(65%～70%)、石英(25%～30%)与斜长石(约5%)。为查明角闪片岩的原岩性质、成岩时代以及构造背景,本文对角闪片岩展开了系统的岩石学、锆石U-Pb定年及全岩地球化学的研究。锆石测点的U-Pb同位素加权平均年龄可划分为>1000Ma、(525.4±8.7)Ma、(234.5±2.7)Ma及(47.1±0.5)Ma等4组,前2组代表了继承锆石的年龄,后2组分别代表了原岩结晶年龄及后期变质事件的年龄。岩石地球化学分析表明,角闪片岩具有较高的FeOT(13.46%～13.74%)、P2O5(0.38%～0.51%)以及Ti O2(4.26%～4.68%),轻重稀土具中等程度分异((La/Yb)N平均7.87),Ti/V和Nb/Y比值较高,富集高场强元素(如Nb、Zr),具有较弱的Ce负异常(δCe=0.89～0.96)与Eu异常(δ...     

华北地区京西煤田侏罗纪煤层中伊利石矿物学特征及成因

为了探讨伊利石对煤化作用和沉积环境的指示作用,以华北地区京西煤田侏罗纪煤层夹矸为研究对象,采用X射线衍射方法（XRD）和X射线荧光方法（XRF）分别测定煤层夹矸的矿物组成和化学组成,研究夹矸中伊利石矿物学特征及成因。结果表明,京西煤田侏罗纪煤层夹矸主要由伊利石、绿泥石和石英组成,其中,伊利石质量分数平均为62.92%。将XRD数据和XRF数据进行对比分析,计算得到伊利石平均化学式为（K_0.37（NH₄）_0.03）Al₂（Si_3.60Al_0.40O₁₀）（OH）₂。京西煤田煤层夹矸中伊利石主要由高岭石转化而来,伊利石的NH₄⁺占层间阳离子的比例具有随沉积古盐度升高而逐渐升高的趋势,n（Si）/n（Al）^Ⅳ具有随煤化程度升高而逐渐降低的趋势,这表明京西煤田侏罗纪煤层夹矸中的伊利石矿物学特征对沉积环境和煤化作用具有一定的指示作用。     

Inorganic species in geologic fluids: correlations among standard molal thermodynamic properties of aqueous ions and hydroxide complexes

Correlations among experimentally determined standard partial molal thermodynamic properties of inorganic aqueous species at 25 degrees C and 1 bar allow estimates of these properties for numerous monatomic cations and anions, polyatomic anions, oxyanions, acid oxyanions, neutral oxy-acid species, dissolved gases, and hydroxide complexes of metal cations. Combined with correlations among parameters in the revised Helgeson-Kirkham-Flowers (HKF) equation of state (Shock et al., 1992), these estimates permit predictions of standard partial molal volumes, heat capacities, and entropies, as well as apparent standard partial molal enthalpies and Gibbs free energies of formation to 1000 degrees C and 5 kb for hundreds of inorganic aqueous species of interest in geochemistry. Data and parameters for more than 300 inorganic aqueous species are presented. Close agreement between calculated and experimentally determined equilibrium constants for acid dissociation reactions and cation hydrolysis reactions supports the generality and validity of these predictive methods. These data facilitate the calculation of the speciation of major, minor, and trace elements in hydrothermal and metamorphic fluids throughout most of the crust of the Earth.     

世界级金银铜铜锌矿床的定量分析

迄今为止，世界范围内已探明的资源总量，计金１９．３万吨，银１７４万吨，铜１５亿２千万吨，铅３亿４千９百万吨，锌７亿１千３百万吨。马上述所探明的每种金属堆积成立方体、则金，边长为２２ｍ的立方体；银，边长为５５ｍ的立方体；铜，边长为５５０ｍ的立方体；铅，边长为３１０ｍ的立方体；锌，边长为４６０ｍ的立方体。