Hydrogeochemical controls on surface and groundwater chemistry in naturally acidic, porphyry-related mineralized areas, southern Rocky Mountains

In southern Rocky Mountains, catchments characterized by acidic, metalliferous waters that are relatively unaffected by human activity usually occur within areas that have active or historical mining activity. The US Geological Survey has utilized these mineralized but unmined catchments to constrain geochemical processes that control the surface- and ground-water chemistry associated with near surface acid weathering as well as to estimate premining conditions. Study areas include the upper Animas River watershed, Lake City, Mt. Emmons, and Montezuma in Colorado and Questa in New Mexico. Although host-rock lithologies range from Precambrian gneisses to Cretaceous sedimentary units to Tertiary volcanic complexes, mineralization is Tertiary in age and associated with intermediate to felsic composition, porphyritic plutons. Pyrite is ubiquitous. Variability of metal concentrations in water is caused by two main factors： mineralogy and hydrology. Parameters that potentially affect water chemistry include： host-rock lithology, intensity of hydrothermal alteration, sulfide mineralogy and chemistry, gangue mineralogy, length of flow path, precipitation, evaporation, and redox conditions. Springs and headwater streams have pH values as low as 2.5, sulfate up to 3700 mg/L and high dissolved metal concentrations （for example： Al up to 170 mg/L; Fe up to 250 mg/L; Cu up to 3.5 mg/L and Zn up to 14 mg/L）. With the exception of evaporative waters, the lowest pH values and highest Fe and Al concentrations occur in water draining the most intense hydrothermally altered areas consisting of the mineral assemblage quartz-sericite-pyrite. Stream beds tend to be coated with iron floc, and some reaches are underlain by ferricrete. When iron-rich ground water interacts with oxygenated waters in the stream or hyporheic zone, ferrous iron is oxidized to ferric iron, which is less soluble, leading to the precipitation of iron oxyhydroxides.     

Naturally acidic and metalliferous waters at unmined volcanogenic massive sulfide deposits in the Bonnifield mining district, Alaska Range, east-central Alaska

The Bonnifield district hosts 26 tmmined volcanogenic massive sulfide （VMS） occurrences. Environmental geochemical samples of water and stream sediment were collected at several occurrences, concentrating on the two best-exposed and largest deposits, Red Mountain （RM） and Sheep Creek （SC）. Limited samples were also collected at the poorly exposed WTF deposit. The deposits are Late Devonian to Early Mississippian, and are hosted by felsic metavolcanic and carbonaceous schist members of the Totatlanika Schist or Keevy Peak Fm. Spring and stream waters at RM and SC have pH values commonly 〈3.5 （as low as 2.4 at RM and 2.5 at SC）, high conductivity （up to 11000 μS/cm）, and very high （Is to 100s mg/L） dissolved contents of Al, Cd, Co, Cu, Fe, Ni, and Pb. Waters at RM are characterized by extremely high REE contents （summed REE median 3200 μg/L, n=33）. At both RM and SC, pyrite oxidation and dissolution produce low pH waters that interact with and dissolve bedrock minerals, resulting in acidic, metal-laden, naturally degraded streams that are mostly devoid of aquatic life. Ferricrete is common. In contrast, WTF barely produces a surficial environmental footprint, mostly due to topography and relief. RM and SC are well exposed in the areas of relatively high relief, and both exhibit extensive areas of quartz-sericite-pyrite-alteration. While WTF shares many of the same deposit-and alteration characteristics, it is concealed by tundra in a large, nearly flat area. Surface water at WTF is absent and outcrops are sparse. Even though WTF is roughly the same size as Red Mountain （both around 3 million tonnes） and has similar base- and precious-metal grades, the surficial geochemical manifestation of WTF is minimal. However, exposure through mining of the altered, mineralized rock at WTF potentially could initiate the same processes of pyrite oxidation, acid generation, and mineral dissolution that are observed naturally at RM and SC.     

Structural Evolvement of Heating Treatment of Mg/AI-LDH and Preparation of Mineral Mesoporous Materials

Although hydrotalcite, or layered double hydroxides （LDHs）, is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/AI-LDH is evaluated by XRD, TEM and N2-BET analyses. The results indicate that the magnesium-aluminum LDH with carbonate as interlayer anion, periclase-like oxides was formed at temperatures of 400-800℃. Meanwhile, 2-3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase-like formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of （Mg, Al）-oxide nano-crystals and nanopores among the nano-crystals. When heating temperature exceeds 1000, the periclase-like （Mg, Al）-oxide is transformed into a composite with periclase （MgO） and spinel phases. The periclase can be re-hydrolyzed and dissolved in HCl solution. After acid treatment, the sample with a high surface area is composed of spinel nano-crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition.     

江苏全力推动建筑节能

新建民用建筑必须强制性达到节能率50％的标准，在我省推行已有半年。在最近一次的建筑节能专项检查中发现，我省绝大部分新建建筑正在实行这一标准，建筑节能已由试点向全面实施发展，自然、节能的“绿色风”吹向了整个建筑领域。记者了解到，“十一五”期间，江苏为全力推动建筑节能要打出系列“组合拳”。     

新课程背景下的好课应该是什么样的

长期以来，我们一直以目的明确、内容正确、方法适当、教学基本功好等作为评价课堂教学的标准，主要看教师在课堂上如何引入、如何过渡、如何掀起高潮、如何画龙点睛做小结。这种评价理念关注的是教师能否酣畅淋漓地表演完自己预设的“课本剧”，关注的是以师为本的教学活动的开展情况。毫无疑问，这不符合当前课程改革倡导的诸多先进教育理念。那么，在新课程背景下，评价一节好课的标准究竟是什么，好课到底应该是什么样的呢？     

广州地区残积土层侧限压缩模量与标准贯入数线性相关关系探讨

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切实加强无障碍建设为构建社会主义和谐社会贡献力量——黄卫副部长在"十五"全国无障碍建设先进城市表彰会暨"十一五"无障碍建设城市标准工作会议上的讲话

同志们:这次“十五”全国无障碍建设先进城市表彰会暨“十一五”无障碍建设城市标准工作会议,是在我国无障碍建设工作进入新的发展阶段和“十一五”开局之年召开的一次重要会议,旨在总结“十五”无障碍建设工作经验,表彰在“十五”期间无障碍建设工作取得突出成绩的城市,研究制定“十一五”无障碍建设城市工作标准,为贯彻落实《中国残疾人事业“十一五”发展纲要》及实施《无障碍建设“十一五”实施方案》做好基础性工作。相信这次会议将对指导和规范未来一个时期我国的无障碍建设工作发挥十分重要的作用。无障碍环境建设是随着我国改革开放…     

华南下寒武统镍钼矿层中铜铅锌矿物的发现及意义

华南扬子地块是我国古热水沉积成矿作用最为发育的地区之一,其热水沉积特性最早引起我国学者的关注。华南下寒武统黑色岩系中赋存多个与热水沉积成矿作用相关的大型、超大型重晶石矿床与N i-Mo-U-V多金属富集层。进一步研究分布在华南扬子地块黑色岩系中的金属、非金属矿床成因及其地球化学特征,对认识华南乃至全球晚震旦—早寒武世生物与环境演化有着十分重要的意义。本文对华南下寒武统镍-钼富集层矿石进行电子探针研究,识别出黄铜矿、黝铜矿等铜的独立矿物;闪锌矿等锌的独立矿物;方铅矿、白铅矿等铅的独立矿物。研究表明,在镍-钼矿石中这些矿物的发现为镍-钼矿层是热水沉积作用产物提供了直接的矿物学证据。     

四川盆地南部志留系碳酸盐泥丘储层发育特征

灰泥丘主要发育在台缘斜坡及台地内部水体比较安静的缓坡环境中,缓坡环境和较弱的水动力条件是形成灰泥丘的两个重要条件。通常情况下礁、丘不相互共生。灰泥丘主要由微生物(蓝藻及其它微观藻类、细菌等)建造的,或者以微生物为主、并有其它多门类生物(珊瑚、苔藓虫、层孔虫、海绵、棘皮、头足、腕足、多门类钙藻等)参与建造的,是主要由灰泥组成、具有穹形特征的碳酸盐岩建隆。其中,灰泥是指粒径小于0.01mm或0.005mm的碳酸盐矿物,而非陆源粘土矿物,是热带、亚热带静水环境中沉积的特有产物之一,并主要由微生物通过新陈代谢、光合作用胶结固化…     

利用激光强度信息分类激光扫描测高数据

三维机载激光扫描测高数据中不仅含有每个激光脚点的位置和高程信息，而且越来越多的系统同时能提供激光脚点回波信号的强度信息。不同反射面介质对激光信号的反射特性不一样．用实测的数据对激光回波信号的强度信息进行统计标定，并基于标定结果．实现了联合激光强度信息和高程信息进行分类的算法．获得了较为满意的结果。