Modeling outflow from the Ernest Henry Fe oxide Cu–Au deposit: implications for ore genesis and exploration

The Ernest Henry Fe oxide Cu–Au (IOCG) deposit (>ca. 1.51 Ga) is hosted by breccia produced during the waning stages of an evolving hydrothermal system that formed a number of tens of metres to a kilometre scale, pre- and syn-ore alteration halos, although no demonstrable patterns have been attributed to fluids expelled through the outflow zones. However, the recognition of a population of hypersaline fluid inclusions representing the ‘spent’ fluids after Cu–Au deposition at Ernest Henry provides the basis to model the geochemical characteristics of the deposit's outflow zones. Geochemical modeling at 300 °C was undertaken at both high and low fluid/rock ratios via FLUSH models involving three host rock types: (1) granite, (2) calc–silicate rock, and (3) graphitic schist. In models run at high fluid/rock ratios, all rock types are essentially fluid-buffered, and produce an albite–quartz–hematite–barite-rich assemblage, although in low fluid–rock environments, the pH, redox, and geochemical character of the host rock exerts a greater influence on the mineralogy of the alteration assemblages (e.g., andradite, Fe–chlorite, and magnetite). Significant sulphide mineralization was predicted in graphitic schist where sphalerite occurred in both low- and high-porosity models, which indicates the possibility of an association between high-temperature IOCG mineralization and lower temperature base metal mineralization.Cooling experiments (from 300 to 100 °C) using the ‘spent fluids’ predict early high-T (300–200 °C) Na-, Ca-, Fe-, and Mn-rich, magnetite-bearing hydrothermal associations, whereas with cooling to below 200 °C, and with progressive fluid–rock interaction, the system produces rhodochrosite-bearing, hematite–quartz–muscovite–barite-rich assemblages. These results show that the radical geochemical and mineralogical changes associated with cooling and progressive fluid influx are likely to be accompanied by major transformations in the geophysical expression (e.g., spectral and magnetic character) of the alteration in the outflow zone, and highlight the potential link between magnetite- and hematite-bearing IOCG hydrothermal systems.     

锰银氧化矿选冶工艺的研究现状及进展

锰银氧化矿在中国是一种重要的矿床类型 ,但在目前经济技术条件下仍属于难选冶和无商业价值的矿石类型。文章对国内外锰银氧化矿选冶技术的研究现状和进展进行了比较全面的评述     

CdTe太阳电池前电极SnO2 :F/SnO2复合薄膜性能分析

减薄CdS窗口层是提高CdS/CdTe太阳电池转换效率的有效途径之一,减薄窗口层会对器件造成不利的影响,因此在减薄了的窗口层与前电极之间引入过渡层非常必要.利用反应磁控溅射法在前电极SnO₂:F薄膜衬底上制备未掺杂的SnO₂薄膜形成过渡层,并将其在N₂/O₂=4 ∶1,550 ℃环境进行了30 min热处理,利用原子力显微镜、X射线衍射仪、紫外分光光度计对复合薄膜热处理前后的形貌、结构、光学性能进行了表征,同时分析了复     

Summertime Surface N2O Concentration Observed on FildesPeninsula Antarctica： Correlation with TotalAtmospheric O3 and Solar Activity

Three-year summertime surface atmospheric N2O concentrations were observed for the first timeon the Fildes Peninsula, maritime Antarctica, and the relationships among the N2O concentration, totalatmospheric O3 amount, and sunspot number were analyzed. Solar activity had an important effecton surface N20 concentration and total O3 amount, and increases of sunspot number were followed bydecreases in the N2O concentration and total O3 amount. A corresponding relationship exists betweenthe N2O concentration and total atmospheric O3, and ozone destruction was preceded by N2O reduction.We propose that the extended solar activity in the Antarctic summer reduces the stratospheric N2O byconverting it into NOx, increases the diffusion of N2O from the troposphere to the stratosphere, decreasesthe surface atmospheric N2O, and depletes O3 via the chemical reaction between O3 and NOx. Ourobservation results are consistent with the theory of solar activity regarding the formation of the AntarcticO3 hole.     

内蒙古哈达门沟金矿床单矿物金浸出实验研究及其地质意义

哈达门沟金矿床产于华北克拉通北缘西段，形成于伸展构造背景中，成矿流体富钾高碱且氧化性强，矿石建造中铁氧化物含量高，并且可见铁氧化物被硫化物交代的现象。文章拟揭示金在铁氧化物中的含量和赋存状态，并探讨金矿床成因。对哈达门沟金矿3种类型矿石中的黄铁矿、铁氧化物(磁铁矿和赤铁矿)单矿物进行金、铁浸取实验，结果表明：铁氧化物含金较高；黄铁矿中的金和铁的浸出曲线不同步，金浸出率与铁浸出率呈负相关，表明黄铁矿中的金主要以颗粒金形式存在；铁氧化物中金、铁同步浸出，浸出率为正相关，表明铁氧化物中的金主要以品格金和(或)胶体吸附金形式存在。哈达门沟金矿床的上述特征均表明其具铁氧化物型金矿床的特点。     

The mineralogy of arsenic in uranium mine tailings at the Rabbit Lake In-pit Facility, northern Saskatchewan, Canada

 A detailed investigation of the mineralogy of As in the tailings of the Rabbit Lake uranium ore processing facility was conducted. The milling/ore extraction process was sampled at three different locations to obtain information about when, where and under what condition secondary As phases form. These samples were compared with four samples of varying As content from the Rabbit Lake in-pit tailings management facility (TMF). Up to 20% As in the tailings are present in primary minerals that reach the tailings directly because they are not dissolved during the uranium extraction. The remaining 80% constitute As that was dissolved during ore extraction and then re-precipitated before being discharged into the tailings pond. It was not possible to conclusively identify any individual re-precipitated (secondary) As minerals in the Rabbit Lake TMF. Indirect evidence from sequential extraction analyses suggests the presence of an amorphous Ca-As phase and a possible, but unlikely, minor amount of an amorphous Fe-As phase. However, the close association between hydrous ferric oxide (HFO) and As could be clearly demonstrated. HFO was identified to be 2-line ferrihydrite and its XRD pattern geometry indicates a substantial amount of adsorbed As. This is in good agreement with SEM, TEM and sequential extraction analyses that all showed the close association of HFO and As. Received: 14 February 2000 · Accepted: 9 May 2000     

由最高最低气温求算的平均气温对我国年平均气温序列影响

针对研究全国近百年平均气温长期变化的实际需要,利用603个测站1961—2002年气温观测资料,比较分析了最高最低平均气温距平序列和4次观测记录平均气温距平序列的差异,讨论了最高、最低气温变化趋势。结果表明：两种统计方法得到的平均气温距平序列及增温速率的差异均不明显,在一定条件下两者可以互相替换。此外,最高、最低气温变化普遍存在不对称现象,且可分为4种类型,这种不对称性对平均气温变化速率并没有明确一致的影响。