试论伊犁盆地库捷尔太铀矿床常量元素的活动性

传统的对控矿层间氧化带的研究往往偏重于铀及其相应的伴生元素(Se、Mo、V、Re、Ga等)的地球化学行为,而对常量元素中非变价元素如：Si、Al、Na、K等研究还很不充分。事实上,层间氧化作用过程中,随着成矿流体的运移和水一岩反应的进行,介质的物理化学条件如Eh、pH等必然会发生显著的改变,而这些改变或多或少的总会在成矿主岩中最常见的元素如：Si、Al、Fe、Na、K的地球化学行为上显示出来。这种改变首先体现在含有上述元素的矿物上的一系列变化,并最终导致元素含量上的改变。不同的元素在这一过程中具有不同的地球化学行为,按照其迁入迁出的强度,这些元素可以划分为活动组分、次活动组分和惰性组分3类。     

黔西晴隆矿区晚二叠世煤地球化学变异的地质成因

运用仪器中子活化分析(INAA)、电离耦合等离子体质谱(ICP—MS)、电离耦合等离子体原子发射光谱(ICP—AES)、X射线荧光光谱(XRF)、冷原子吸收光谱(CVAAS)、离子选择性电极法(ISE)、逐级化学提取试验(SCEE)等,结合带能谱仪的扫描电镜(SEMEDX)和MPV—Ⅲ显微镜下观察的煤岩学特征的分析,对贵州晴隆矿区上二叠统含煤岩系8号煤层中微量元素的含量和赋存特征及其影响因素进行了研究。发现该煤层中Cu(263.4μg／g)、Cr(154．2μg／g)、Hg(0．86／μg／g)、Mo(82．47μg／g)、Ni(63．3μg／g)、Pb(200．4／μg／g)、Se(4．25／μg／g)、U(154．8／μg／g)、Zn(214．6／μg／g)和Zr(754．3μg／g)等元素异常富集;而As和F的含量不高,其含量分别为1．58／μg／g和83．4μg／g。逐级化学提取结果显示,该煤层中Hg、Mo、Ni、Pb、Se和Zn元素主要赋存在低温热液成因的黄铁矿脉中;Cr、U和Zr主要存在于粘土矿物中,其中Cr和Zr可能与康滇古陆陆源碎屑供给有关;Cu不仅与粘土矿物有关,而且也和煤中黄铁矿有关。表明低温热液流体和陆源碎屑供给对该煤中主要微量有害元素的含量和赋存特征起了决定作用。     

GIS中的空间建模器技术及其在全国矿产资源潜力预测中的应用

在GIS技术环境下开展资源定量评价, 实现资源评价工作的自动化、数字化、智能化是矿产资源勘查与预测的重要发展趋势.为了给地质勘查与预测人员、定量建模人员、GIS分析与操作人员提供共同研究和技术讨论平台, 提出了在矿产资源预测全过程使用的建模技术.介绍了建模技术的基本概念、空间模型建立、图形建模技术以及建模技术在矿产资源定量预测中的应用, 介绍了GeoDAS GIS中的建模技术基本功能以及建模技术在空间对象相关分析、证据(信息) 图层提取、不规则地质单元划分、预测后验概率绘制等矿产资源预测工作中的应用实例.应用结果表明, 建模技术为地质预测人员、定量建模人员、GIS操作人员开展综合研究和空间决策提供了公共的平台, 有助于实现模型的共享和操作过程的自动化.      

层序地层格架下的速度研究及其应用: 以准噶尔盆地腹部石南21井区为例

在对准噶尔盆地腹部石南21井区岩性地层油气藏研究中, 将层序地层学的研究成果与地球物理中的速度分析相结合, 以高精度层序地层格架为指导, 对层序地层格架内的地层进行速度研究, 目的在于预测出储层内部有利砂岩发育区及储层埋深, 为井位论证提供重要的基础资料.首先以岩心资料、测井资料和地球化学资料为基础, 确定层序界面识别标志, 通过单井相划分、合成地震记录制作, 在地震剖面上识别层序界面, 通过层序对比和追踪, 建立起研究区等时地层格架, 并以此作为速度研究的模型层位, 利用模型迭代层速度反演法, 有针对性地进行层序地层格架内部的层速度分布规律研究.结果表明, 研究目标层序白垩系清水河组(CX0-CX3) 的层速度分布规律是: 南及东南部砂体发育区地层速度高, 北部泥岩相对发育区地层速度低, 速度的高低反映了砂岩含量的多少; 速度图上高速区和低速区的平面分布形态, 与属性图的平面分布范围和形态基本吻合, 振幅属性图上的异常体是高速异常体, 速度与振幅类地震属性在反映储层非均质性和砂体横向变化方面是相互印证、相互补充的.此外, 在层序格架下的层速度反演基础上得到的目标层序CX3界面的平均速度图, 其系统误差和随机噪音的影响小, 时深转换所得CX3界面构造图等值线走势合理, 即使井资料较少, 也能得到形态正确精度较高的构造图.模拟勘探评价5个阶段的误差分析表明, 钻前预测误差不超过0.33%, 有效降低了岩性地层油气藏勘探的深度设计误差和风险.      

西藏札达县夏浦沟的放射虫硅质岩和岛弧火山岩: 新特提斯洋内俯冲体系的记录?

在西藏阿里地区夏浦沟野外调查发现放射虫硅质岩、熔岩组合.放射虫硅质岩SiO₂含量在89.47%~92.94%之间, Si/Al在43~67之间, Al/ (Al+Fe+Mn) 比值在0.68~0.74之间, MnO/TiO₂平均比值为0.60, Ce/Ce*平均值为0.89, La_N/Ce_N平均值1.09, 指示它位于洋盆和大陆边缘过渡的环境, 总体更接近大陆边缘环境.伴生的火山熔岩以安山质为主, 具低TiO₂ (0.75%~0.98%)、轻稀土弱富集和源自板片流体的易溶元素如Ba、U、Pb相对轻稀土富集, 亏损高场强元素(HFSE) Nb、Ta、Ti等, 指示形成于岛弧环境, 很可能是中生代新特提斯洋洋内俯冲系统的组分.放射虫动物群主要包括Alievium cf.regulare、Alievium cf.fatuum、Archaeospongoprunum cf.patricki、Archaeodictyimitra mitra Dumitrica等早白垩世分子, 其提供了岛弧活动时间上限的约束.      

Characteristic of crustal structure beneath the rifts in southern Tibetan plateau

The method of 2-D travel time inversion,which can be applied to determining 2-D velocity structure and in-terfaces simultaneously,is used in this paper to reprocess the data of Paiku Co-Pumoyingcuo seismic profile across the Ny-ima-Tingri rift and Shenzha-Dinggye rift. P-wave velocity structure and interfaces beneath the profile are obtained. The in-terfaces in the crust near Tingri and Dinggye which are located on rifts have a tendency to uplift,and velocities of middle and lower crusts are high. Low veloc...     

Simulated multi-scale watershed runoff and sediment production based on GeoWEPP model

The runoff and sediment yield data from the Qiaozidonggou, Qiaozixigou, and Lu＇ergou watersheds, in the Loess Plateau of China are used to calibrate and validate the runoff and sediment yield simulated by GeoWEPP model of the WEPP Model at watershed scale. The indices of relative error, R, correlation coefficient, Re, and Nash-Suttcliffe efficiency coefficient Ens are used to evaluate the model fit. The eco-hydrological responses in the Luoyugou and Lu＇ergou watersheds are also forecast based on the WEPP Model. Meanwhile, the relation between vegetation pattern changes and sediment yield in the watershed is discussed, and the responses of runoff and sediment yield in the watersheds concerning forest growth stages are studied. The results show that the relative errors of simulated values of runoff and sediment yield are below 30%, the correlation coefficients axe above 0.90, and the Nash-Suttcliffe efficiency coefficients axe above 0.80. The simulation results present satisfactory performance, thus, the model could be used to simulate the runoff and sediment yield in these small watersheds. It is also observed that soil erosion tended to become severe as precipitation increased in the watershed, while soil erosion has a decreasing trend as forest cover increases and vegetation pattern is optimized. When the watershed is fully covered by forest, erosion and sediment yield are minimized. When the forest cover is about 30% and evenly distributed in the watershed, the erosion intensity is lower than if the forest cover is collectively distributed in the watershed. Erosion varies with different forest growth stages in the watershed; it is more serious at the young and near planting stage and is the smallest at the mature forest stage.     

Precision estimation and geomorphological analysis based on the DEM generated by InSAR: Taking Damxung-Yangbajain area as an example

Digital elevation model (DEM) can be generated by interferometric synthetic aperture radar (InSAR). In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite (ERS)-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1:50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared er...     

Geothermic activity and seismotectonics in the altitude of the Tibetan plateau

In the present analysis on the relationships among the depth of lithosphere brittle fracture,seismotectonics and geothermal anomalous active in Tibetan plateau were investigated using the seismic dada from ISC and Chinese seismic net and geothermal data.The results suggest that the region of anomalously geothermal activity almost coincides with that of the normal faulting type earthquake.The geothermal anomaly activity region coincides spatially with that of the events deeper than 60 km as well as.The norma...     

A case study of spatial heterogeneity of soil moisture in the Loess Plateau, western China： A geostatistical approach

Soil moisture distribution shows highly variation both spatially and temporally. This study assesses the spatial heterogeneity of soil moisture on a hill-slope scale in the Loess Plateau in West China by using a geostatistical approach. Soil moisture was measured by time-domain reflectometry （TDR） in 313 samples. Two kinds of sampling scales were used （2 × 2 m and 20 ×20 m） at two soil layers （0-30 cm and 30-60 cm）. The general characteristics of soil moisture were analyzed by a classical statistics method, and the spatial heterogeneity of soil moisture was analyzed using a geostatistical approach. The results showed that the spherical model is the best-fit model to simulate soil moisture on the experimental hill-slope. The parameters of this model indicated that the spatial dependence of soil moisture in the selected hill-slope was moderate. Even the 2 × 2 m sampling scale was too coarse to show the detailed spatial variances of soil moisture in this area. The dependent distance increased from 27.4 m to 494.16 m as the sampling scale became coarse （from 2× 2 m to 20 ×20 m）. A map of soil moisture was generated by using original soil moisture data and interpolated values determined by the Kriging method. The average soil moisture （area weighted） in the different layers of soil was calculated on the basis of this map （10.94% for the 0-30 cm soil layer, 11.88% for the 30-60 cm soil layer）. This average soil moisture is lower than the corresponding average effective soil moisture, which suggests that the soil moisture is not sufficient to support vegetation in this area.