Mikroskopische und mikroanalytische Untersuchungen an metallischen Kügelchen aus Tiefseesedimenten des Zentralen Pazifik

Metallic spherules from Central Pacific Ocean sediments (“Valdivia” expedition VA 05-1, 1973) were studied by means of the ore microscope and by electron microprobe. The data suggest that most of the spherules are of meteoritic origin, i.e. ablation drops from meteorites as suggested in former studies on spherules from marine environment by Schmidt and Keil (1966), Finkelmann (1970, 1972) and others. The metallic spherules contain up to about 60% Ni, 37% Fe and 3% Co. Unusually high contents of Cr (up to 12%) were noted in some spherules.     

Geological structure of the Mediterranean Sea floor (based on geological—Geophysical data)

According to geophysical data, the Mediterranean Sea depressions are noted for a peculiar type of the earth's crust. The sedimentary rock sequence is of great thickness (8–15 km) and is of platform-type dislocation. Several structural stages are distinguished in the sedimentary complex. The youngest of them are the Messinian (evaporite) and Pliocene—Quaternary stages. The consolidated part of the earth's crust shows small thickness and is divided into large blocks. Vertical dislocations of the large crustal blocks which were conditioned by condensation—rarefaction and the upper mantle substance migration were at the base of Mediterranean sea floor transformation.     

哈萨克斯坦共和国地震学数据库简介

建立哈萨克斯坦共和国地震学数据库是CASIN国际项目的一部分,应由中亚各国来共同完成。项目主要目的旨在建立地震学数据库,以作为今后减小哈萨克斯坦共和国地震危险性的工作基础。哈萨克斯坦共和国地震学数据库由下列子系统构成:1)文件输入子系统;2)信息检索和提交子系统;3)信息元数据存储子系统;4)档案库运行控制子系统;5)信息安全子系统。哈萨克斯坦共和国地震学数据库有以下功能:1)永久存储综合信息并上报和收集(记录)其他资料;2)存储数据和资料计算;3)电子文档的长期存储和管理;4)规定序号进行信息查询和文件的联机保证;5)信息统计和…     

Holocene overbank deposition in the drainage basin of Lake Khanka

Overbank deposits in the Komissarovka River valley consist of alternating silt, clay silt, sand, and soils produced by lacustrine, alluvial, and aeolian deposition and by soil formation. Silt and sand layers in the lower part of the section correlate with the events of Early Holocene transgression and Middle Holocene regression of Lake Khanka. Deposition in the lowermost reaches of the Komissarovka River provides a faithful record of local Holocene landscapes controlled by level changes in Lake Khanka.     

Extraction and recovery of precious metals from electronic waste printed circuit boards by bioleaching acidophilic fungi

Printed circuit boards contain precious metals. They are produced in large volumes, rendering them an important component of the electronic waste. In view of the heterogeneity of the metals present, reprocessing of electronic waste is a heinous task. The present study focused on leaching of valuable metals from electronic waste printed circuit boards using Aspergillus niger DDNS1. The adaptation phases began at 0.1, 0.5 and 1.0% of fine powder of printed circuit boards with 10% inoculum and were optimized with three effective factors, viz. initial pH, particle size and pulp density, to achieve the maximum simultaneous recovery of the valuable metals. The interactions of these metals were also deciphered using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectrum and atomic absorption spectroscopy. The results indicated that extraction of the precious metals was accomplished mainly through the unique organic acids originating from A. niger DDNS1. The initial pH played an important role in the extraction of the precious metals and the metals precipitate formation. The leaching rate of the metals was generally higher at low powder dosage of printed circuit boards. The toxicity of the printed circuit boards had little effect on two-step bioleaching at the pulp density of 0.1% compared to one-step bioleaching. The two-step bioleaching process was followed under organic acid-forming conditions for the maximum mobilization of metals. Thus, the precious metals from printed circuit boards could be mobilized through fungal bioleaching which promises an important industrial application in recycling of electronic wastes.     

Geology and petrology of the lava complex of Young Shiveluch Volcano, Kamchatka

Detailed geological and petrological-geochemical study of rocks of the lava complex of Young Shiveluch volcano made it possible to evaluate the lava volumes, the relative sequence in which the volcanic edifice was formed, and the minimum age of the onset of eruptive activity. The lavas of Young Shiveluch are predominantly magnesian andesites and basaltic andesites of a mildly potassic calc-alkaline series (SiO₂ = 55.0–63.5 wt %, Mg# = 55.5–68.9). Geologic relations and data on the mineralogy and geochemistry of rocks composing the lava complex led us to conclude that the magnesian andesites of Young Shiveluch volcano are of hybrid genesis and are a mixture of silicic derivatives and a highly magnesian magma that was periodically replenished in the shallow-depth magmatic chamber. The fractional crystallization of plagioclase and hornblende at the incomplete segregation of plagioclase crystals from the fractionating magmas resulted in adakitic geochemical parameters (Sr/Y = 50–71, Y < 18 ppm) of the most evolved rock varieties. Our results explain the genesis of the rock series of Young Shiveluch volcano without invoking a model of the melting of the subducting Pacific slab at its edge.     

Tourmalinites from the stratiform peraluminous metamorphic suite of the Central Namaqua Mobile Belt (South Africa)

Tourmalinites as proximal fades equivalents of stratiform peraluminous metamorphic rocks occur stratigraphically below base metal deposits and above thick metarhyolite horizons. Their premetamorphic protoliths are believed to have originated by tourmaline precipitation from exhalative B-, F- and W-rich brines also transporting aluminous clay colloids and dissolved silica. Tourmaline chemistry is used as an effective petrogenetic sensor. The tourmalines are Al-saturated, alkali-deficient dravite-schorl solid solutions, which are in the compositional range of tourmalines originated by exhalative processes. F-substitution in tourmalines is governed by Fe-F-avoidance. F is relatively enriched in the tourmalines and can potentially be used as a tracer for the source of primary hydrothermal solutions. Ti is introduced into the tourmalines by the substitution scheme Ti+Al^IV=Al_Y+Si. The high Ti-contents of the tourmalines as well as those of coexisting muscovites represent evidence of high-temperature metamorphism. Many tourmalines exhibit continuous zoning, which can partly be attributed to external fluid influx near peak metamorphic conditions.     

Determination of Gold in Twenty Geochemical Reference Samples by Flameless Atomic Absorption Spectrometry

After acid digestion, gold is extracted with MIBK and determinated by flameless atomic absorption spectrometry. The results for six USGS reference samples and fourteen French geochemical standards are presented and discussed. The agreement with working values for these standards is in the range of pm 5%.     

The thermal reaction of Venezuelan lateritic bauxites with glycerol

Goethite contained in lateritic bauxites or in artificial mineral admixtures is completely transformed into peculiar Fe-alkoxide compounds by reaction with glycerol at 245°C. Magnetic spinel oxides result from hydrolysis by boiling water of alkoxides obtained from the artificial admixtures. On the other hand, the production of magnetic spinel materials is not observed in alkoxides derived from natural lateritic samples. This may be caused by the high amount of Al substituting for Fe in these Venezuelan lateritic goethites.