Early biodégradation of ligneous organic materials and its relation to ore deposition in the tréves zn-pb ore body (gard, france)

1986 ◽  
Vol 10 (4-6) ◽  
pp. 1005-1013 ◽  
Author(s):  
J.R. Disnar ◽  
B. Gauthier ◽  
A. Chabin ◽  
J. Trichet
Keyword(s):  
Organic Materials ◽  
Ore Body ◽  
Ore Deposition

Distribution of Gold and Associated Ore-Bearing Elements in Gold-Copper-Pyrite Ores of the Kyzylbulag Deposit (Lesser Caucasus, Azerbaijan)

2020 ◽  
pp. 51-59
Author(s):  
M.I. Mansurov ◽  
B.H. Galandarov ◽  
U.I. Karimli ◽  
A.I. Huseynov
Keyword(s):  
Cluster Analysis ◽  
Elemental Composition ◽  
Native Gold ◽  
Ore Body ◽  
Hydrothermal Stage ◽  
Copper Pyrite ◽  
Lesser Caucasus ◽  
Pyrite Ores ◽  
Host Rocks ◽  
Ore Deposition

The article presents the results of studies of the distribution of gold and associated ore elements in gold-copper pyrite ores of the Kyzylbulag deposit. It was established that the elemental composition of ores and host rocks of the deposit includes Cu, Pb, Au, Ag, Ni, As, Sb, Bi, and Mo, of which Au, Cu, Ag, and Zn are the more stable. The behavior of elements was also studied for the entire ore body, as a result of which they are divided by cluster analysis at R (5 %) - 0.1 into two groups: 1) Au, Cu and Ag; 2) Pb and Zn. The closest relationship in the first group was found between Au and Cu, Au and Ag, Ag and Cu; and in the second, between Pb and Zn. Acquired results confirm that gold and the copper are the major components of ore in the field expressed generally in the mineral paragenesis of chalcopyrite - native gold shown in the independent hydrothermal stage of ore deposition.

scholarly journals Post-Ore Processes of Uranium Migration in the Sandstone-Hosted Type Deposits: 234U/238U, 238U/235U and U–Pb Systematics of Ores of the Namaru Deposit, Vitim District, Northern Transbaikalia

2021 ◽  
Vol 63 (4) ◽  
pp. 287-299
Author(s):  
V. N. Golubev ◽  
N. N. Tarasov ◽  
I. V. Chernyshev ◽  
A. V. Chugaev ◽  
G. V. Ochirova ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Cross Sections ◽  
Isotopic Age ◽  
Pb Isotope ◽  
Quaternary Period ◽  
Ore Body ◽  
Catchment Areas ◽  
Uranium Migration ◽  
Ore Deposition ◽  
Ore Zones

Abstract To assess the nature of the post-ore behaviour of uranium in the Namaru deposit (Khiagda ore field), U–Pb isotope systems and the isotopic composition of uranium (234U/238U and 238U/235U) were studied. The studied samples represent different ore zones of the deposit and were collected along cross-sections both vertically and horizontally. Wide variations in the isotopic composition of uranium and U–Pb isotopic age have been established. Deviations of the 234U/238U ratio from equilibrium values, which for some samples exceed 50%, along with significant variations in the isotopic age, indicate that permafrost layer, which covered the catchment areas of paleovalleys with meteoric oxygen-containing waters ca. 2.5 Ma ago, did not lead to preserving uranium ores at the deposit. Uranium migration took place during the Quaternary period. The effective combining the U–Pb dating and 234U/238U data in assessing the post-ore redistribution of uranium made it possible to recognize: removal of uranium from some zones of the ore body and its accompanying redeposition in others. Wide variations in the 238U/235U (137.484–137.851) ratios throughout the entire studied cross-sections can be explained by the different locations of samples relatively to the ore deposition front and change in redox conditions as this front advanced. Depletion of the light isotope 235U in the lower zone of the ore body may be associated with the influence of ascending carbonic waters established in the regional basement. The effect of such waters on uranium-bearing rocks causes predominant leaching of light 235U.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

STM of freeze-fracture replicas: Problems and promises

1993 ◽  
Vol 51 ◽  
pp. 68-69
Author(s):  
J. T. Woodward ◽  
J. A. N. Zasadzinski
Keyword(s):  
Scanning Tunneling Microscope ◽  
Organic Materials ◽  
Freeze Fracture ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Molecular Scale ◽  
Organic Surfaces ◽  
Metal Layers ◽  
Conductive Surfaces

The Scanning Tunneling Microscope (STM) offers exciting new ways of imaging surfaces of biological or organic materials with resolution to the sub-molecular scale. Rigid, conductive surfaces can readily be imaged with the STM with atomic resolution. Unfortunately, organic surfaces are neither sufficiently conductive or rigid enough to be examined directly with the STM. At present, nonconductive surfaces can be examined in two ways: 1) Using the AFM, which measures the deflection of a weak spring as it is dragged across the surface, or 2) coating or replicating non-conductive surfaces with metal layers so as to make them conductive, then imaging with the STM. However, we have found that the conventional freeze-fracture technique, while extremely useful for imaging bulk organic materials with STM, must be modified considerably for optimal use in the STM.

Stabilizing pyritic material

1989 ◽  
Vol 4 ◽  
pp. 244-248 ◽  
Author(s):  
Donald L. Wolberg
Keyword(s):  
Significant Contribution ◽  
Organic Materials ◽  
Sedimentary Rocks ◽  
Iron Sulfides ◽  
Decomposition Products ◽  
Iron Minerals ◽  
Pyrite Formation ◽  
Organic Sediments ◽  
Freshwater Environments

The minerals pyrite and marcasite (broadly termed pyritic minerals) are iron sulfides that are common if not ubiquitous in sedimentary rocks, especially in association with organic materials (Berner, 1970). In most marine sedimentary associations, pyrite and marcasite are associated with organic sediments rich in dissolved sulfate and iron minerals. Because of the rapid consumption of sulfate in freshwater environments, however, pyrite formation is more restricted in nonmarine sediments (Berner, 1983). The origin of the sulfur in nonmarine environments must lie within pre-existing rocks or volcanic detritus; a relatively small, but significant contribution may derive from plant and animal decomposition products.

‘Robenhausien’ in the Hunterian Museum

1981 ◽  
Vol 8 (1) ◽  
pp. 1-12
Author(s):  
Isobel M Hughes
Keyword(s):  
Organic Materials ◽  
Neolithic Period ◽  
Plant Remains ◽  
Neolithic Europe ◽  
The University

Summary A report is presented of a study of the material from Robenhausen and other sites of the Neolithic period in Switzerland, part of the Bishop Collection in the Hunterian Museum, the University of Glasgow. The material is described and its likely setting within the cultural sequence of the Swiss Neolithic is discussed. The importance of the collection is seen to lie in the finds of organic materials, artefacts and macroscopic plant remains, which afford a rare glimpse of detail in craftsmanship and husbandry in Neolithic Europe.

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