The Hyrkkölä Native Copper Mineralization: a Natural Analogue for Copper Canisters

1996 ◽  
Vol 465 ◽  
Author(s):  
Nuria Marcos Perea
Keyword(s):  
Ph Value ◽  
Open Fractures ◽  
Surface Zone ◽  
Minimum Concentration ◽  
Near Surface ◽  
Native Copper ◽  
Copper Sulfides ◽  
Copper Mineralization ◽  
Reducing Conditions ◽  
Nuclear Fuel Waste

ABSTRACTThe Hyrkkölä U-Cu mineralization is located in south-western Finland, near the Palmottu analog site, in crystalline, metamorphic bedrock. The age of the mineralization is estimated to be between 1.8 and 1.7 Ga. The existence of native copper and copper sulfides in open fractures in the near-surface zone allows us to study the native copper corrosion process in conditions analogous to a nuclear fuel waste repository.From the study of mineral assemblages or paragenesis, it appears that the formation of copper sulfide (djurleite, Cu1.934S) after native copper (Cu°) under anoxic (reducing) conditions is enhanced by the availability of dissolved hydrogen sulfide (HS) in the groundwater circulating in open fractures in the near-surface zone. The minimum concentration of HS in the groundwater is estimated to be of the order of 10-5 M (∼ 10-4 g/1) and the minimum pH value not lower than about 7.8 as indicated by the presence of calcite crystals in the same fracture.The present study is the first one performed on occurrences of native copper in reducing, neutral to slightly alkaline groundwaters. Thus, the data obtained is of most relevance in improving models of anoxic corrosion of copper canisters.

New Data on the HyrkkÖlÄ Native Copper Mineralization: A Natural Analogue for the Long-Term Corrosion Of Copper Canisters

1999 ◽  
Vol 556 ◽  
Author(s):  
N. Marcos ◽  
L. Ahonen ◽  
R. Bros ◽  
P. Roos ◽  
J. Suksip ◽  
...  
Keyword(s):  
Fracture Surface ◽  
Copper Sulfide ◽  
Mineral Assemblage ◽  
Open Fractures ◽  
Depth Interval ◽  
Uranyl Compounds ◽  
Native Copper ◽  
Copper Mineralization ◽  
Activity Ratios ◽  
Minimum Age

AbstractThe Hyrkkölä U-Cu mineralization located in south-western Finland is reassessed with reference to the corrosion mechanisms affecting the stability of native copper and the time-scales of corrosion processes. The mineral assemblage native copper – copper sulfide occurs in open fractures at several depth intervals within granite pegmatites (GP). The surfaces of these open fractures have accumulations of uranophane crystals and other unidentified uranyl compounds. The secondary uranium minerals are mainly distributed around copper sulfide grains. Microscopic intergrowths of copper sulfides and uranyl compounds also have been observed. Groundwater samples were collected from the vicinity of the Cu samples. The hydrogeochemical features of these samples indicate that the present conditions are oxidising. The minimum age of U(VI) transport and deposition is about 200 000 years. This age is indicated by 234U/238U and 230Th/234U activity ratios of uranophane. The age of the hexavalent uranium precipitation may be somewhat later than the last influxes and/or demobilisation of sulfur.The mineral assemblage native copper – copper oxide (cuprite) occurs only at one depth interval within altered granite pegmatite. The fracture surface was coated by smectite. The content of uranium in smectite was 69–75 ppm U. The 234U/238U and 230Th/234U activity ratios of smectite showed that it has been exposed to recent groundwaters (e.g., during the last million years). The pH of the groundwater at this interval was near neutral (6.9). The copper grains present at this fracture surface were as large as 1 mm in diameter and had rims of cuprite of 0.01 to 0.1 mm thick. The smallest grains were totally oxidised.

DISPERSION IN SEISMIC SURFACE WAVES

Geophysics ◽  
1951 ◽  
Vol 16 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Milton B. Dobrin
Keyword(s):  
Surface Waves ◽  
Water Waves ◽  
Seismic Refraction ◽  
Wave Theory ◽  
Wave Dispersion ◽  
Surface Zone ◽  
Surface Wave Dispersion ◽  
Near Surface ◽  
Arrival Times ◽  
Ground Roll

A non‐mathematical summary is presented of the published theories and observations on dispersion, i.e., variation of velocity with frequency, in surface waves from earthquakes and in waterborne waves from shallow‐water explosions. Two further instances are cited in which dispersion theory has been used in analyzing seismic data. In the seismic refraction survey of Bikini Atoll, information on the first 400 feet of sediments below the lagoon bottom could not be obtained from ground wave first arrival times because shot‐detector distances were too great. Dispersion in the water waves, however, gave data on speed variations in the bottom sediments which made possible inferences on the recent geological history of the atoll. Recent systematic observations on ground roll from explosions in shot holes have shown dispersion in the surface waves which is similar in many ways to that observed in Rayleigh waves from distant earthquakes. Classical wave theory attributes Rayleigh wave dispersion to the modification of the waves by a surface layer. In the case of earthquakes, this layer is the earth’s crust. In the case of waves from shot‐holes, it is the low‐speed weathered zone. A comparison of observed ground roll dispersion with theory shows qualitative agreement, but it brings out discrepancies attributable to the fact that neither the theory for liquids nor for conventional solids applies exactly to unconsolidated near‐surface rocks. Additional experimental and theoretical study of this type of surface wave dispersion may provide useful information on the properties of the surface zone and add to our knowledge of the mechanism by which ground roll is generated in seismic shooting.

STUDYING OF SPACE WEATHER ELECTROMAGNETIC PARAMETERS OF IONOSPHERE IN «OBSTANOVKA 1-STEP» EXPERIMENT ON THE RUSSIAN SEGMENT OF THE ISS

2021 ◽  
pp. 20-41
Author(s):  
Stanislav I. KLIMOV ◽  
Valery A. GRUSHIN Valery A ◽  
Kalman BALAJTHY ◽  
Dichko Enchev BACHVAROV ◽  
Serhiy M. BELYAEV ◽  
...  
Keyword(s):  
Plasma Wave ◽  
Space Weather ◽  
Space Station ◽  
Scientific Instrument ◽  
Surface Zone ◽  
Electromagnetic Parameters ◽  
Wave Processes ◽  
Near Surface ◽  
Ionosphere Plasma ◽  
Electric And Magnetic Fields

The program and results of physical research in the international (5 countries) space experiment «The situation (1 stage)», conducted onboard the Russian segment of the International Space Station (ISS) in the period 27.02.2013 to 09.05.2015, is presented. The methods and scientific tasks of the experiment and the composition of the Plasma-wave complex based on the combined wave diagnostics method are described in detail, and designed to conduct geophysical studies through long-term monitoring measurements of the electromagnetic parameters of the ionosphere plasma and plasma-wave processes associated with the manifestation in the ionosphere of the solar-magnetosphere-ionosphere and ionosphere-atmosphere relationships, i. e., parameters of space weather. Studies in the near-surface zone of plasma-wave processes of interaction of an extra-large spacecraft, like ISS, with the ionosphere are necessary for both applied and fundamental geophysical studies. The electric and magnetic fields and currents measured at the surface of the ISS are determined by the parameters of the surrounding ionosphere plasma and the nature of the interaction of the materials on the surface with this medium. Key words: orbital space station, fundamental space research, ionosphere plasma, plasma-wave processes, electromagnetic fields and radiation, scientific instrument, space weather.

scholarly journals Modern Geodetic Measurement Techniques in Gravimetric Studies on the Example of Gypsum Karst in the Siesławice Region

2018 ◽  
Vol 35 ◽  
pp. 03002 ◽  
Author(s):  
Sławomir Porzucek ◽  
Monika Łój ◽  
Karolina Matwij ◽  
Wojciech Matwij
Keyword(s):  
Laser Scanning ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Field Studies ◽  
Surface Zone ◽  
Three Dimensional Model ◽  
Geodetic Measurement ◽  
Near Surface ◽  
Gypsum Karst

In the region of Siesławice (near Busko-Zdrój, Poland) there are unique phenomena of gypsum karst. Atmospheric factors caused numerous gypsum outcrops, canals and underground voids. The article presents the possibility of using non-invasive gravimetric surveys supplemented with geodetic measurements to illustrate karst changes occurring around the void. The use of modern geodetic measurement techniques including terrestrial and airborne laser scanning enables to generate a digital terrain model and a three-dimensional model of voids. Gravimetric field studies allowed to map the anomalies of the gravitational field of the near-surface zone. Geodetic measurement results have made it possible to accurately determine the terrain correction that supplemented the gravimetric anomaly information. Geophysical interpretation indicate the presence of weathered rocks in the near surface zone and fractures and loosened zones located surround the karst cave.

Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

2009 ◽  
Author(s):  
Ulrich Noseck ◽  
Vaclava Havlova ◽  
Juhani Suksi ◽  
Thomas Brasser ◽  
Radek Cervinka
Keyword(s):  
Current Knowledge ◽  
Natural Analogue ◽  
Near Surface ◽  
Co2 Partial Pressure ◽  
Long Term Stability ◽  
Reducing Conditions ◽  
Phosphate Mineral ◽  
Sedimentary System ◽  
The Impact

Groundwater data from the natural analogue site Ruprechtov have been evaluated with special emphasis on the uranium behaviour in the so-called uranium-rich clay/lignite horizon. In this horizon in-situ Eh-values in the range of −160 to −280 mV seem to be determined by the SO42−/HS− couple. Under these conditions U(IV) is expected to be the preferential redox state in solution. However, on-site measurements in groundwater from the clay/lignite horizon show only a fraction of about 20% occurring in the reduced state U(IV). Thermodynamic calculations reveal that the high CO2 partial pressure in the clay/lignite horizon can stabilise hexavalent uranium, which explains the occurrence of U(VI). The calculations also indicate that the low uranium concentrations in the range between 0.2 and 2.1μg/l are controlled by amorphous UO2 and/or the U(IV) phosphate mineral ningyoite. This confirms the findings from previous work that the uranium (IV) mineral phases are long-term stable under the reducing conditions in the clay/lignite horizon without any signatures for uranium mobilisation. It supports the current knowledge of the geological development of the site and is also another important indication for the long-term stability of the sedimentary system itself, namely of the reducing geochemical conditions in the near-surface (30m to 60 m deep) clay/lignite horizon. Further work with respect to the impact of changes in redox conditions on the uranium speciation is on the way.

NATIVE METALS IN THE MUSKOX INTRUSION

1965 ◽  
Vol 2 (3) ◽  
pp. 188-215 ◽  
Author(s):  
J. A. Chamberlain ◽  
C. R. McLeod ◽  
R. J. Traill ◽  
G. R. Lachance
Keyword(s):  
Experimental Studies ◽  
Native Metal ◽  
Native Copper ◽  
Nickel Iron ◽  
Native Iron ◽  
Reducing Conditions ◽  
Cobalt Iron ◽  
Central Regions ◽  
Reducing Environment

The following native metals have been identified in the Muskox intrusion: native iron, native nickel–iron (awaruite), native cobalt–iron (wairauite), and native copper. Mineral distributions and textures indicate that the native metals formed more or less contemporaneously, during the period of serpentinization of the host dunites and related rocks.Conditions during serpentinization must have been more reducing in the central and lower parts of the layered series than in the margins and upper parts of the intrusion. This is indicated by the fact that most native metals are abundant in the central regions and are essentially lacking elsewhere, even in strongly serpentinized zones. This zoning suggests that reducing conditions may have been generated internally, possibly as a result of the serpentinization process itself. The composition of the primary olivine of forsterite80–88 together with the presence of abundant secondary magnetite in equivalent serpentinites indicates that a redox reaction, olivine + water = serpentine + magnetite + hydrogen, contributed to the development of a progressively more reducing, or hydrogen-rich, fluid phase.Natural phase relations indicate that each native metal formed primarily in situ as a result of the decomposition of specific earlier formed minerals that had become unstable in the reducing environment. Native iron appears to have been formed by the reduction of magnetite; awaruite by the reduction of pentlandite; wairauite by the reduction of an unknown phase, possibly cobalt pentlandite or cobaltian pyrite; and native copper by the reduction of chalcopyrite. The feasibility of most of these reactions was confirmed by experimental studies carried out in systems open to moist hydrogen.

scholarly journals Copper-Containing Agates of the Avacha Bay (Eastern Kamchatka, Russia)

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1124
Author(s):  
Galina Palyanova ◽  
Evgeny Sidorov ◽  
Andrey Borovikov ◽  
Yurii Seryotkin
Keyword(s):  
Raman Spectroscopy ◽  
Powder Diffraction ◽  
Fluid Inclusions ◽  
Silica Matrix ◽  
Native Copper ◽  
X Ray ◽  
Eastern Kamchatka ◽  
Copper Mineralization ◽  
Avacha Bay ◽  
Copper Sulphides

The copper-containing agates of the Avacha Bay (Eastern Kamchatka, Russia) have been investigated in this study. Optical microscopy, scanning electron microscopy, electron microprobe analysis, X-ray powder diffraction, Raman spectroscopy, and fluid inclusions were used to investigate the samples. It was found that copper mineralization in agates is represented by native copper, copper sulphides (chalcocite, djurleite, digenite, anilite, yarrowite, rarely chalcopyrite) and cuprite. In addition to copper minerals, sphalerite and native silver were also found in the agates. Native copper is localized in a siliceous matrix in the form of inclusions usually less than 100 microns in size—rarely up to 1 mm—forming dendrites and crystals of a cubic system. Copper sulphides are found in the interstices of chalcedony often cementing the marginal parts of spherule aggregates of silica. In addition, they fill the micro veins, which occupy a cross-cutting position with respect to the concentric bands of chalcedony. The idiomorphic appearance of native copper crystals and clear boundaries with the silica matrix suggest their simultaneous crystallization. Copper sulphides, cuprite, and barite micro veins indicate a later deposition. Raman spectroscopy and X-ray powder diffraction results demonstrated that the Avacha Bay agates contained cristobalite in addition to quartz and moganite. The fluid inclusions study shows that the crystalline quartz in the center of the nodule in agates was formed with the participation of solutions containing a very low salt concentration (<0.3 wt.% NaCl equivalent) at the temperature range 110–50 °C and below. The main salt components were CaCl2 and NaCl, with a probable admixture of MgCl2. The copper mineralization in the agates of the Avacha Bay established in the volcanic strata can serve as a direct sign of their metallogenic specialization.

Rain impact soil crust. II. Some effects of surface slope, drop size and soil variation

Soil Research ◽  
1991 ◽  
Vol 29 (2) ◽  
pp. 291 ◽  
Author(s):  
AJ Moss
Keyword(s):  
Drop Size ◽  
Surface Zone ◽  
Special Role ◽  
Soil Crust ◽  
Surface Slope ◽  
Small Surface ◽  
Near Surface ◽  
Loose Packing ◽  
Soil Variation ◽  
Stable Particles

Formation and non-formation of the rain-impact soil crust were studied experimentally over ranges of surface-slope, drop-size and soil variation. In these contexts, the formative process was found to be very versatile. However, stable particles, of a size just movable on the soil surfaces by raindrops, appear to play a special role in preventing crust development. Becoming juxtaposed on the surface, these particles form clusters which allow hydraulic penetration of water from impacting drops, through their large pores. This maintains loose packing in the near-surface zone as opposed to the compaction associated with crust formation where only small surface pores exist. A method of soil modification, involving increasing the proportion of durable, barely rain-movable particles in soils, is suggested as a means of combating crusting on a long-term basis.

Chemical diagenesis in near-surface zone above oil fields in geochemical exploration

2018 ◽  
Vol 95 ◽  
pp. 33-44
Author(s):  
Igor S. Sobolev ◽  
Nikolay P. Bredikhin ◽  
Tatiana Bratec ◽  
Alla Yu. Falk ◽  
Oleg S. Tolkachev ◽  
...  
Keyword(s):  
Oil Fields ◽  
Surface Zone ◽  
Geochemical Exploration ◽  
Near Surface

scholarly journals Application of electric resistivity tomography for investigation of geological situation closed to railways

2019 ◽  
Vol 265 ◽  
pp. 03005
Author(s):  
Dmitriy Gorbach ◽  
Valeriya Yakimenko ◽  
Olga Konovalova
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Electric Resistivity ◽  
Practical Work ◽  
Surface Zone ◽  
Two Dimensional ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Geological Situation ◽  
Engineering Geophysics

The paper reviews methods of engineering geophysics which can be applied to sections of railway tracks. The method of electrical resistivity tomography is used to study the properties of the geological situation under an engineering structure. In the course of practical work, two-dimensional geoelectric sections were obtained. Interpretation of the sections allowed to understand the structure of the near-surface zone.

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