柿竹园夕卡岩中钙铝-钙铁榴石系列石榴子石形成条件的实验研究

柿竹园夕卡岩中有早、晚形成的两种产状石榴子石。本文为查明其形成物理化学条件及与矿化的关系,采用矿区天然花岗岩、灰岩和夕卡岩化早期形成的石榴子石为试样进行了模拟实验研究。实验结果表明:夕卡岩化早期石榴子石是在温度400—750℃,压力500—1000bar,pH=5—8条件下,由富含Si、Al、Fe、Cl、F等组分的热液与上泥盆统佘田桥组灰岩交代反应形成的;晚期石榴子石是在温度250—700℃,压力500—1000bar,pH=5—14条件下,由富含Si、Al、F等组分的带钨溶液与早期石榴子石交代反应产生重结晶作用形成的。     

Rock Magnetic Investigation of Historical Lavas Used in Palaeointensity Studies

Five samples from historical lava flows on Mt. Etna, which had previously been used in a palaeointensity study, were examined using a combination of rock magnetic and microscopic techniques to elucidate the causes of failure of palaeointensity determination. The samples were characterised using a combination of low-temperature susceptibility (LT-), Bitter pattern imaging and scanning electron microscope (SEM). High-temperature susceptibility curves and hysteresis loops had been previously measured by Calvo et al. (2001). Of the five samples only one gave an accurate palaeointensity. This sample was deuterically oxidised and consisted of large exsolved ore grains. It was only possible to distinguish this sample either optically or magnetically from a similar sample by the LT- warming curves; the unsuccessful sample displayed alteration in the LT- warming curves, which was not readily observed in the high temperature susceptibility curves. It is proposed that the measurement of LT- curves before and after heating could be a more sensitive method of determining suitability for palaeointensity determination than previous rock magnetic pre-selection techniques.     

粘土矿物在过去环境变化研究中的应用

粘土矿物是一种广泛分布于地表的沉积物,其组合及含量的变化记录了源区过去气候环境变化的信息。因此,可以根据粘土矿物的含量和组合变化等信息推知其形成时期的气候环境,重建古环境,揭示气候环境演变的规律。粘土矿物是一种研究古环境演化重要的代用指标,在过去气候环境变化研究中有广阔的应用前景。     

基于Web平台的岩石矿物数据处理软件新进展

基于Web(WordwideWeb万维网 )平台的岩石矿物数据处理软件是按照浏览器 服务器的模式工作 ,即用户以客户端浏览器为计算平台 ,而计算的应用程序及数据库在服务器端运行。本文介绍了当前岩石矿物数据处理软件的发展现状和趋势及成功开发基于Web平台的岩石数据处理程序的范例 ,探讨了开发基于Web平台的岩石矿物数据处理软件的实现方法及优越性 ,从而论证了建立基于Web平台的岩石矿物数据处理软件的必要性和可行性     

含粘粒砂土抗液化性能的试验研究

通过对含粘粒砂土所作的试验研究, 包括: 粘粒矿物成分不同、粘粒含量不同的重塑土样所作的室内动三轴试验; X光衍射试验, 试验结果对比分析后, 得出了含粘粒砂土抗液化性能的特性。并得出以下结论: (1)粘粒矿物成分不同, 也引起砂土动力稳定性的变化; (2 )动剪应力强度与粘粒含量并非呈单调增加关系, 而呈抛物线型, 并给出回归方程; (3)含粘粒的砂土, 其抗液化能力最低点总是在粘粒含量 8.5～ 9.5 %之间。     

Adjustment of a Formulated Sediment for Sediment Testing with Caenorhabditis elegans (Nematoda)

The OECD soil, which is standardised for use in the sediment toxicity with the midge Chironomus riparius revealed inhibition of the nematode Caenorhabditis elegans in body growth length and egg production of 41.0% and 84%, respectively. 18 formulated sediments were tested to optimise the sediment composition for growth and reproduction of C. elegans. Their components were chosen to simulate native sediments, whereby different quantities and different clay minerals were tested. The mixture that we found to be optimal in our experiments consisted of 5% sphagnum peat, 70% calcitic sand, 0.5% dolomite limestone, 4.5% iron(III) oxide, and a clay combination of 1.5% chlorite and 18.5% aluminium(III) oxide. When applying this mixture to C. riparius, the new formulated sediment improved also growth in comparison to the OECD sediment.     

Dissolution of well and poorly ordered kaolinites by an aerobic bacterium

Previous research by our group (e.g., [Chem. Geol. 132 (1996) 25; Geochim. Cosmochim. Acta 64 (2000) 1363]) has shown that an aerobic Pseudomonas mendocina bacterium enhances Fe(hydr)oxide dissolution in order to obtain Fe under Fe-limited conditions. The P. mendocina is incapable of utilizing Fe as a terminal electron acceptor and requires several orders of magnitude lower Fe concentrations than do dissimilatory Fe reducing bacteria. The research reported here compared the effects of the P. mendocina on dissolution of well and poorly ordered Clay Minerals Society Source Clay kaolinites KGa-1b and KGa-2, respectively, under Fe-limited conditions. KGa-1b and KGa-2 contain 0.04 and 0.94 bulk wt.% Fe, respectively, and their surface Fe/Si atomic RATIOS=0.008 and 0.012. Following strong cleaning of the kaolinites in 5.8 M HCl at 85 °C, the surface Fe/Si atomic ratios decreased to 0.004 and 0.008, respectively. Both kaolinites also developed a Si-enriched surface precipitate upon strong cleaning.

Because the P. mendocina take up Fe, we could not measure Fe release from the kaolinite directly, but rather had to monitor it indirectly by comparing microbial populations sizes under Fe-limited growth conditions. We found that microbial growth on uncleaned, weakly cleaned, and strongly cleaned kaolinites increased with the amount of Fe readily available to organic ligands as estimated by dissolution in 0.001 M oxalate (pH 3). This suggests that it is the amount of readily accessible Fe that controls Fe acquisition and hence microbial growth. The trend is based on only a relatively small range of kaolinite Fe contents, and the research thus needs to be expanded to include kaolinites with a broader range of bulk and surface Fe concentrations.

Significant enhancement of Al release was observed in the presence of the bacteria, along with generally some enhancement of Si release. This enhancement of kaolinite dissolution could be related to an observed pH increase from 7–8 to 9 in the presence of the bacteria and/or to production of Al chelating agents. The P. mendocina produce a variety of organic exudates, including siderophores [Chem. Geol. 132 (1996) 25; Geomicrobiology (2001b)], and further studies into the effects of the siderophores on Al complexation and on kaolinite dissolution are ongoing.     

Partitioning of heavy metals on soil samples from column tests

In this study, column tests were used to determine the retention capability of three types of estuarine alluvia collected adjacent to landfill sites in South Wales. Selective sequential extraction (SSE) was used to study the retention mechanisms of heavy metals in the soil columns obtained from leaching experiments. Acid digestion was later used to check the validity of the SSE results. Breakthrough curves show good retention of heavy metal ions (Pb, Cu, and Zn) by all soils, where almost 99% of heavy metals were retained with the C_e/C_o values in the order of 10⁻³. The retention strength of these soils was observed to be constant up to five pore volumes (PV). This corresponds with the pH of the effluents and pore water of soil slices, which also show good buffering capacity against very acidic leachate up to 5PV. The heavy metal extraction profiles from SSE show very similar trends with the retention profiles from the leaching experiments, where heavy metals were retained mainly at the top part where the leachate entered the column. SSE indicates qualitatively that heavy metals precipitated with carbonates and amorphous materials (oxides/hydroxides) are higher than heavy metal retention via exchangeable mechanisms. The mass balance calculation gives range of deviation of 1–16% of the total soil extraction. The distribution of the heavy metals with various soil constituents are ranked in the following order: Carbonates>Amorphous oxides hydroxides>Organic matter>Exchangeable phases.     

吉林省六道沟硅藻土的矿物学特征研究

六道沟硅藻土矿床是我国北方中—大型优质硅藻土矿床。本文通过电镜扫描、x光衍射、红外吸收光谱、差热分析和化学分析等手段。研究了该矿床硅藻土的一般矿物学特征。     

江华河路口黄玉的宝石学特征研究

本文介绍了研究区黄玉产出的地质环境及其颜色、形态、硬度、比重、折射率、多色性、包裹体、红外光谱、重量分布、可用率、加工方法等宝石学特征。