地球主磁场的能量密度谱及其长期变化

根据BJ地磁场模型和第8代国际地磁参考场(IGRF)模型，计算并分折了1690～2000年期间地球表面主磁场和分量的能量密度谱及其长期变化。结果表明1690～2000年期间主磁场的能量密度谱一直在减小，其主要原因是由于偶板子磁场的衰减产生的，而非偶板子磁场的能量密度谱在1690～1780年期间减小，1780～1890年增大，1890年以后快速增大。在地磁场总能谱的变化中，Z分量的贡献起主要作用。能量密度随谐波阶数的变化在半对数坐标中近似线性，非偶板子场的等效磁源深度位于核幔边界附近，n＝1，2谐波项的等效磁源位于地球内核边缘，其位置随时间变化。1780和1890年前后是地磁场变化的转折时期。能量密度谱的长期变化存在大约60a的周期规律。     

沉积模型和储层随机建模

沉积模型是地层分析的重要工具，可以分为比例尺模型、概念模型和数学模型三大类型，其中数学模型又可分为确定性模型和随机模型。在实际地层分析及模拟工作中，特别是在小尺度问题的研究中，采用随机模型(或称统计学模型)往往更为有利。储层随机建模技术，作为这方面研究的典范，近年来成为储层预测和风险评价的一项较为有效的手段。然而，由于研究目标的复杂性，不同沉积模型之间的嵌套制约关系亦应引起重视。     

Changes in the yield of chlorophyll a from dissolved available inorganic nitrogen after an enrichment event—applications for predicting eutrophication in coastal waters

An understanding of the dynamic relationship between nitrogen supply and the formation of phytoplankton biomass is important in predicting and avoiding marine eutrophication. This relationship can be expressed as the short-term yield q of chlorophyll from dissolved available inorganic nitrogen (DAIN), the sum of nitrate, nitrite and ammonium. This paper communicates the results of a continuous culture nitrate enrichment experiment undertaken to investigate the cumulative yield of chlorophyll from DAIN (q). The purposes of the study were: to acquire a better understanding of the relationship between chlorophyll formation and DAIN; to obtain values that could be used in models for predicting eutrophication. The results of a time series experiment carried out using microplankton (all organisms <200 μm in size) indicate that the parameter q does not have a single value but is affected by the ecophysiological response of phytoplankton to changing nutrient status after an enrichment event. It is also dependent on changes in the allocation of nitrogen between autotrophs and heterotrophs. The value of yield obtained at the height of the bloom can be represented by q (max) (2.35 μg chl (μmol N)⁻¹). The post-bloom, steady state value of q can be represented by q_eq (0.95 μg chl (μmol N)⁻¹). The microcosm steady state yield was not significantly different from the median value obtained from synoptic studies of Scottish west coast waters. It is proposed that q_eq is the most appropriate value for assessing the general potential for eutrophication resulting from continuous nutrient enrichment into coastal waters. It is further proposed that q (max) be used for cases of sporadic enrichment and where a short burst of unrestricted growth may be detrimental.     

Dynamic dyke propagation deduced from tilt variations preceding the March 9, 1998, eruption of the Piton de la Fournaise volcano

During the hour preceding the March 9, 1998, eruption of the Piton de la Fournaise volcano, the deformation network of the Observatory recorded some large deformations in the summit area. A broadband seismic station of the GEOSCOPE global network, RER, is located about 8 km away from the summit of the volcano. Signals from that station may be interpreted as tilt changes. The combination of the above two kinds of signals allows, by using a tensile fault model, to constrain the geometry as well as some characteristics (volume, propagation velocity) of the dyke that intruded the summit area during the hour preceding the beginning of eruptive activity.     

我国金属矿山“超设计服务年限”的问题及其重要启示

文章提出我国金属矿山“超设计服务年限”，即矿山的“实际服务年限”超过了按照“合理服务年限”原则所确定的“设计服务年限”的那一部分“服务年限”的新概念。我国主要金属矿产25个矿种10 618座矿山的统计资料表明；70．87％的大型矿山超设计服务，“超设计服务年限”平均可达10．75年；中型矿山的79．07％“超设计服务年限”平均可达10．74年；73．41％的小型矿山的“超设计服务年限”平均仅有2．25年。我国25种金属矿产8 107座矿山“超期服役”为国家作出的“直接贡献”总共是；每年多产矿石29．21亿吨，多创产值3060．75亿元，多缴税金306．82亿元，多提供就业岗位606．33万人。“超设计服务年限”的新概念表明，我国大中型矿山所在的矿区，不仅大多具有较好的成矿地质条件和较大的资源潜力，而且还有随着勘查程度和认识水平的提高而进一步扩大资源潜力的可能。     

城市地质工作的初步探讨

回顾了国内外城市地质工作的发展历程，阐述了中国城市经济区地质工作的总体思路和内容。由于中国城市的规模、性质、资源承载力、地质环境特征不同，城市地质调查、评价的对象、内容也有所差异。城市地质工作具有学科的综合性、地域的独特性、工作的持久性、方法的多样性等一系列特点。城市地质工作拟在基础地质调查、主题填图、综合评价研究3个层面上展开。城市地质调查评价涵盖资源开发利用、环境安全、灾害评估和信息集成四大主题。     

甘肃白银折腰山型和石青硐型块状硫化物矿床综合信息找矿模型研究

甘肃白银厂-石青硐火山岩带是北祁连地区块状硫化物矿床成矿带的主要地段，在其中已发现6个工业矿床。典型矿床的综合信息找矿模型研究对于进一步开展矿体定位预测具有重要意义。文章将已发现的矿床划分为火山喷口Cu(Zn)型(折腰山型)、火山喷口斜坡Zn—Pb-Cu型(小铁山型)和火山沉积洼地Pb-Zn-Cu型(石青硐型)三(亚)类，并通过对典型矿床的地质特征、地球物理特征、地球化学特征及找矿标志等进行对比分析和研究，建立了折腰山型、石青硐型两类矿床的综合信息找矿模型。应用该模型在黑石山地区进行成矿预测，取得了良好的效果。     

Groundwater flow through Pleistocene glacial deposits in the rapidly urbanizing Rouge River–Highland Creek watershed,City of Scarborough,southern Ontario,Canada

The city of Scarborough lies on the eastern margin of the Greater Toronto Area of southern Ontario, Canada, along the northern coastline of Lake Ontario. The City has a population of 500,000 and is presently one of the fastest growing communities in Canada. The City is expanding northwards onto rural land on the south slope of the large Pleistocene glacial Oak Ridges Moraine system. The moraine system is underlain by a thick (150 m) succession of tills, sands and gravels and is a regionally-significant recharge area for three principle aquifer systems that discharge to numerous watercourses that flow to Lake Ontario. Protection of deeper aquifers from surface-generated urban contaminants is a particular concern. A groundwater flow model using Visual MODFLOW was developed for the 350-km² Rouge River–Highland Creek (RRHC) drainage basin using an extensive GIS-based collection of subsurface geological, geophysical and hydrogeological data, maps of land use and surficial geology. The RRHC model was calibrated against point water level data, known potentiometric surfaces of the principal aquifers and baseflow measurements from streamflow gauging stations and determined to be within acceptable limits. Water balance calculations indicate that 70% of the basin recharge (106,000 m³/day) enters the Upper Aquifer along the crest and immediate flanks of the Oak Ridges Moraine. To the south, Upper Aquifer water moving through fractured till aquitards accounts for more than 75% of recharge to deeper aquifers. Water quality data confirm previous observations that urban- and rural-sourced contaminants (chlorides and nitrates) present in Upper Aquifer waters are moving rapidly into deeper aquifers. Some 83% of total RRHC recharge water is ultimately discharged as baseflow to creeks draining to Lake Ontario; the remainder discharges to springs and along eroding lakeshore bluffs. Model results demonstrate that deeper aquifers are poorly protected from urban contaminants and that long-term protection of ground and surface water quality has to be a priority of municipal planners if the resource is not to be severely degraded. Electronic Publication     

Characterizing the rheology of laterite slurries

The viscous behaviour of laterite slurries was characterized by measurements of shear stress at constant and changing shear rates. Steady state stresses were obtained after accounting for the settling solids: the values show that the fluids possess viscosities of order 100 mPa s and are moderately shear-thinning, for solid volume fractions from 0.06 to 0.18 and for shear rates between 10 and 1000 s⁻¹. Transient stress measurements were made for steps down in shear rate and for ramps down and up in shear rate. It was found that the Bingham–Maxwell model provides good fits to the transient data, both at low concentrations, where yield behaviour is dominant, and at high concentrations, where elasticity is dominant. For volume fractions of 0.10 or greater, relaxation times were found from step tests to be of order 10 s, but relaxation times found from the ramp tests were generally several times higher.     

黑河干流山区流域月径流计算模型

西北内陆河山区流域天然来水量的准确预测对于维持区域可持续发展和生态环境的保护具有重大的意义。鉴于这些山区流域地形、地貌、植被景观复杂，观测站点稀疏，建立了6种月平均流量的计算模型，效果都很好。所进行的数值试验表明，山区平均月降水量、月平均气温、平均月蒸发量和出山月平均流量相互之间存在复杂的非线性关系。降水和气温都是影响月蒸发力和平均流量的一个综合因素。气温是影响含有冰雪融水的山区流域产流的一个极为重要的因素，但降水、气温物蒸发力不足以完全综合反映产流过程，应该探讨加入新的因子。