scholarly journals Gold in the Oxidized Ores of the Olympiada Deposit (Eastern Siberia, Russia)

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 190
Author(s):  
Sergey A. Silyanov ◽  
Anatoly M. Sazonov ◽  
Yelena A. Zvyagina ◽  
Andrey A. Savichev ◽  
Boris M. Lobastov
Keyword(s):  
Low Temperature ◽  
Native Gold ◽  
Middle Zone ◽  
Eastern Siberia ◽  
Sulfide Ores ◽  
Lower Zone ◽  
Invisible Gold ◽  
Gold Particles ◽  
New Formation

Native gold and its satellite minerals were studied throughout the 300 m section of oxidized ores of the Olympiada deposit (Eastern Siberia, Russia). Three zones are identified in the studied section: Upper Zone ~60 g/t Au; Middle Zone ~3 g/t Au; Lower Zone ~20 g/t Au. Supergene and hypogene native gold have been found in these zones. Supergene gold crystals (~1 μm), their aggregates and their globules (100 nm to 1 μm) predominate in the Upper and less in Middle Zone. Relic hypogene gold particles (flattened, fracture and irregular morphology) are sporadically distributed throughout the section. Spongiform gold occurs in the Lower Zone at the boundary with the bedrock, as well as in the bedrock. This gold formed in the process of oxidation of aurostibite, leaching of impurities and its further dissolution. Hypogene gold is commonly isolated but for supergene gold typically associated with ferric (hydr)oxides. New formation of gold occurred due to oxidation of sulfide ores and release of “invisible” gold, as well as dissolution, mobilization and re-deposition of metallic hypogene gold. A model for the formation of oxidized ores with the participation of meteoric and low-temperature hydrothermal waters has been proposed.

scholarly journals Genesis of Carbonate Breccia Containing Invisible Gold in Taebaeksan Basin, South Korea

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1087
Author(s):  
Sang-Gun No ◽  
Maeng-Eon Park ◽  
Bong-Chul Yoo ◽  
Seung-Han Lee
Keyword(s):  
South Korea ◽  
Carbonate Rock ◽  
Gold Deposits ◽  
Invisible Gold ◽  
Gold Particles ◽  
X Ray ◽  
Taebaeksan Basin ◽  
The Matrix ◽  
Backscattered Electron

The Yemi breccia developed and is distributed within the Paleozoic carbonate rock (Maggol Formation) in the central part of the Taebaeksan Basin, South Korea. Explanation for the genesis of the Yemi breccia has been controversial. We investigated the petrological and mineralogical properties of the breccia and the matrix materials at 60 outcrops. The Yemi breccia is divided into crackle, mosaic, and chaotic breccias based on morphology. In addition, these are divided into blackish, reddish, grayish, and white to pinkish matrix breccias according to the materials of the matrix. Quartz, calcite, pyrite, hematite (after pyrite), and minor epidote, chlorite, and opaque materials mainly comprise the matrix materials. The pyrite grains from the Yemi breccia can be divided into two types based on the mineral texture: diagenetic and hydrothermal. We analyzed the chemistry of pyrite and hematite (after pyrite) from the Yemi breccia with an electron probe X-ray microanalyzer (EPMA). Invisible gold was detected within the pyrite grains by EPMA and disseminated micron-sized isolated gold particles were discovered by backscattered electron (BSE) images. The texture of Au-bearing pyrite and gold particles in the Yemi breccia is especially well matched with pyrite and gold from the Shuiyindong Carlin-type hydrothermal gold deposits, China. Therefore, we suggest an important role of hydrothermal fluid in karstification within the Paleozoic carbonate rock.

New data on invisible gold in disseminated sulfide ores of the Natalka deposit

2006 ◽  
Vol 409 (2) ◽  
pp. 879-883 ◽  
Author(s):  
A. V. Volkov ◽  
A. D. Genkin ◽  
V. I. Goncharov
Keyword(s):  
Sulfide Ores ◽  
Invisible Gold

Ultra-low Contact Resistivity by High Concentration Germanium and Boron Ion Implantation Combined with Low Temperature Annealing

1996 ◽  
Vol 427 ◽  
Author(s):  
A. Murakoshi ◽  
M. Iwase ◽  
M. Koike ◽  
H. Niiyama ◽  
K. Suguro
Keyword(s):  
Structural Analysis ◽  
Low Temperature ◽  
Lattice Strain ◽  
Contact Resistivity ◽  
High Concentration ◽  
Low Resistivity ◽  
Low Temperature Annealing ◽  
Formation Method ◽  
Heavy Dose ◽  
New Formation

AbstractA new formation method for an ultra-low resistivity contact and structural analysis are discussed. In this study, a minimum contact resistivity of 6.9× 10−9 Ω·cm2 has been successfully obtained in an AlSi(lwt%)Cu(0.5wt%) alloy / Si system by using heavy dose ion implantations of Ge and B combined with low temperature annealing as low as 550°C. Structural analysis on the Si surface layer has been carried out. As a result, it was found that the crystal lattice was expanded in-plane by 6% in the Si layer near the surface because of the high concentration of Ge and no relaxation of lattice strain at such a low temperature. It was also found that super-saturation of B was stably formed in this system. An ultra-low resistivity contact is considered to be a result of these combined effects.

scholarly journals Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948

1996 ◽  
Vol 42 (141) ◽  
pp. 261-270 ◽  
Author(s):  
Wendy Lawson
Keyword(s):  
Structural Evolution ◽  
Aerial Photographs ◽  
Middle Zone ◽  
Normal Flow ◽  
Lower Zone ◽  
Longitudinal Zonation ◽  
Velocity Gradients ◽  
Flow Processes ◽  
Zone Ii ◽  
Glacier Velocity

AbstractАn excellent photographic database, comprising 12 sets of vertical aerial photographs taken between 1948 and 1993, has enabled the structural glaciology of surge-type Variegated Glacier, Alaska, U.S.A., tо be analyzed for a period that spans two surge cycles and includes the effects of three surges. The glacier-wide patterns of crevasse development at the end of each of these surges, which occurred in 1947–48, 1964–65 and 1982–83, were remarkably similar, despite differences in surge intensities and extents. At the end of each surge a three-fold longitudinal zonation of crevasse orientation characterised that part of the glacier that had been affected by surge activity. This zonation comprises: (i) transverse crevasses in a narrow upper zone, (ii) superimposed longitudinal and transverse crevasses in an extensive middle zone, and (iii) longitudinal crevasses in a narrow lower zone. The main difference between patterns produced by successive surges was small variations in the extent оf the three zones. During quiescence, the most intense crevasse development occurs in the upper glacier in the latter part of quiescence, and is a function of increasingly steep down-glacier velocity gradients developing in the buildup to the impending surge. Some crevassing also develops in the central part of the glacier in mid-quiescence that is not related to the surge nature of the glacier, but to normal flow processes over bedrock. There is no structural evidence to indicate that any of the tributaries of Variegated Glacier surge. This observation suggests that the bulb-like loops in the medial moraines at Variegated Glacier form during quiescence as a result of the steady flow of the tributaries into the stagnant trunk glacier, rather than as a result of tributary surges.

Vulnerability Assessment of Farmer’s Livelihood to Flood in An Giang Province

2019 ◽  
pp. 251660261986062
Author(s):  
P. X. Phu ◽  
N. N. De
Keyword(s):  
Climate Change ◽  
Adaptive Capacity ◽  
Global Environmental Change ◽  
Vulnerability Index ◽  
Livelihood Strategies ◽  
Middle Zone ◽  
Lower Zone ◽  
Knowledge And Skills ◽  
Global Environmental ◽  
Local Farmers

This study, conducted in An Giang Province of Vietnam, assesses the vulnerability and adaptability of local farmers to the flood in different conditions. Livelihood Vulnerability Index (LVI) proposed by Hahn, Riederer, and Foster (2009, Global Environmental Change, 19(1), 74–88) was applied for livelihood vulnerability analysis of different flooding zones (upper, middle and lower zones) in low flooding condition. Research results showed that LVI of different flooding zones are decreasingly dependent on major components of social networks, knowledge and skills, natural resources, finance and incomes, livelihood strategies, and natural disaster and climate variability. In which, LVI of Phu Huu commune in An Phu district which locates in the upper zone is 0.397 higher than LVI of two communes located in the lower parts of the river: Vinh An commune, Chau Thanh district (middle zone; LVI: 0.299) and Vinh Phuoc commune, Tri Ton district (lower zone; LVI: 0.357). Adaptive capacity of Phu Huu commune (0.415) is also higher than Vinh An (0.304) and Vinh Phuoc (0.355) communes. It reflects the direct correlation between LVI and adaptive capacity. The research recommends some solutions to reduce the vulnerability on livelihoods due to floods in the context of climate change.

scholarly journals Process and Mechanism of Gold Mineralization at the Zhengchong Gold Deposit, Jiangnan Orogenic Belt: Evidence from the Arsenopyrite and Chlorite Mineral Thermometers

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 133 ◽  
Author(s):  
Si-Chen Sun ◽  
Liang Zhang ◽  
Rong-Hua Li ◽  
Ting Wen ◽  
Hao Xu ◽  
...  
Keyword(s):  
Phase Separation ◽  
Gold Deposit ◽  
Native Gold ◽  
Gold Mineralization ◽  
Early Stage ◽  
Orogenic Belt ◽  
Alteration Zone ◽  
Composition Analysis ◽  
Invisible Gold ◽  
Polymetallic Sulfides

The Zhengchong gold deposit, with a proven gold reserve of 19 t, is located in the central part of Jiangnan Orogenic Belt (JOB), South China. The orebodies are dominated by NNE- and NW- trending auriferous pyrite-arsenopyrite-quartz veins and disseminated pyrite-arsenopyrite-sericite-quartz alteration zone, structurally hosted in the Neoproterozoic epimetamorphic terranes. Three stages of hydrothermal alteration and mineralization have been defined at the Zhengchong deposit: (i) Quartz–auriferous arsenopyrite and pyrite; (ii) Quartz–polymetallic sulfides–native gold–minor chlorite; (iii) Barren quartz–calcite vein. Both invisible and native gold occurred at the deposit. Disseminated arsenopyrite and pyrite with invisible gold in them formed at an early stage in the alteration zones have generally undergone syn-mineralization plastic-brittle deformation. This resulted in the generation of hydrothermal quartz, chlorite and sulfides in pressure shadows around the arsenopyrite and the formation of fractures of the arsenopyrite. Meanwhile, the infiltration of the ore-forming fluid carrying Sb, Cu, Zn, As and Au resulted in the precipitation of polymetallic sulfides and free gold. The X-ray elements mapping of arsenopyrite and spot composition analysis of arsenopyrite and chlorite were carried out to constrain the ore-forming physicochemical conditions. The results show that the early arsenopyrite and invisible gold formed at 322–397 °C with lgf(S2) ranging from −10.5 to −6.7. The crack-seal structure of the ores indicates cyclic pressure fluctuations controlled by fault-valve behavior. The dramatic drop of pressure resulted in the phase separation of ore-forming fluids. During the phase separation, the escape of H2S gas caused the decomposition of the gold-hydrosulfide complex, which further resulted in the deposition of the native gold. With the weakening of the gold mineralization, the chlorite formed at 258–274 °C with lgf(O2) of −50.9 to −40.1, as constrained by the results from mineral thermometer.

Silicate Mineralogy of the Middle Zone Cumulates and Associated Gabbroic Rocks from the Insch Intrusion, NE Scotland

1988 ◽  
Vol 52 (366) ◽  
pp. 309-322 ◽  
Author(s):  
W. J. Wadsworth
Keyword(s):  
Principal Components ◽  
Intermediate Position ◽  
Middle Zone ◽  
Lower Zone ◽  
Fine Grained ◽  
Geographical Variations ◽  
Mineral Compositions ◽  
Complex Relationships ◽  
A Minor ◽  
Block Faulting

AbstractThe Middle Zone (MZ) of the Insch intrusion lies in a geographically intermediate position between the Lower Zone (LZ) and Upper Zone (UZ) cumulate sequences, but is more complicated than either in comprising two intricately associated, but texturally distinct, components, the MZ cumulates and the fine-grained granular gabbros (FGG). In addition, there is a minor group of porphyritic granular gabbros (PGG), containing abundant plagioclase phenocrysts. A further variety of gabbroic rock, namely quartz-biotite norite (QBN) occupies a similarly intermediate position in the Boganclogh extension of the main Insch mass. These principal components (MZ cumulates, FGG, and QBN) show considerable mineralogical overlap with each other and with the lower part of the UZ succession (UZa). Unlike the UZ rocks, they are essentially olivine-free (apart from the most basic granular gabbros) and consist mainly of plagioclase, orthopyroxene, and Ca-rich clinopyroxene, with accessory Fe-Tioxides and minor interstitial biotite and/or hornblende. Mineral compositions are in the range An70–55 (plagioclase), En71–44 (opx), and Ca46Mg42Fe12 to Ca45Mg30Fe25 (cpx), but in detail each rock group can be characterized mineralogically as well as texturally. It is concluded that the MZ cumulates and FGG (including PGG) are essentially complementary, formed in different locations, and under slightly different conditions, but in the same magma chamber. The complex relationships between them, and the apparently haphazard geographical variations in mineral compositions, may be the combined results of the magmatic events, possibly including the movement of large xenolithic fragments, and later block faulting. The substantial compositional overlap of the more evolved MZ cumulates by UZa is explained in terms of replenishment by magma of slightly more primitive (and potentially olivine-bearing) composition after the deposition of the MZ. The Boganclogh QBN is believed to represent a more hydrous fraction of the Insch MZ magma.

Salt-gradient Solar Ponds for Solar Energy Utilization

1975 ◽  
Vol 2 (4) ◽  
pp. 289-292 ◽  
Author(s):  
Carl E. Nielsen
Keyword(s):  
Low Temperature ◽  
Solar Energy ◽  
Energy Utilization ◽  
Lower Zone ◽  
Cost Information ◽  
Solar Ponds ◽  
Solar Energy Utilization ◽  
Temperature Heat ◽  
Salt Gradient

Salt-gradient solar ponds function as systems to collect and store solar energy. The upper zone of the pond is rendered non-convective by the salt gradient and serves as a partially transparent insulator, permitting some of the incident solar energy to penetrate to the bottom and heat the lower zone to a temperature as high as 95°C. A pond 3 m deep and 150 m2 in area is expected to provide all of the winter heat required by a house of the same area in Columbus, Ohio.Solar ponds occur in Nature. Research on artificial solar ponds was first begun in Israel in 1958 and some research has since been done in other countries. Recent results obtained by the author and collaborators indicate that solar ponds will be simple to operate and will provide low-temperature heat at a cost of perhaps $0.010 per kW-hr thermal. Experiments to obtain more definitive cost information are now in progress.

Les diverses interpretations du terme de "Bartonien"

1940 ◽  
Vol S5-X (3-6) ◽  
pp. 105-119
Author(s):  
Lucien Morellet ◽  
J. Morellet
Keyword(s):  
Middle Zone ◽  
Paris Basin ◽  
Lower Zone

Abstract The various interpretations of the term "Bartonian." Concludes that the term Bartonian should be extended to include all formations from the Lutetian to the Oligocene. Three major subdivisions on the basis of distinct paleontologic zones are recognized: a lower zone--Sables moyens of the Paris basin, Upper Bracklesham beds of the London basin, and Ledian sands of Belgium; a middle zone--Cresnes sands (Paris basin), Barton clay (London basin), Wemmel sands (Belgium); and an upper zone--Pholadomya-bearing marls and gypsum beds (Paris basin), and Long Mead End Sands and Lower Headon beds (London basin). The upper zone is apparently not present in Belgium.

The large-scale structure of the Earth's crust beneath southern Britain

1984 ◽  
Vol 121 (6) ◽  
pp. 621-624 ◽  
Author(s):  
A. Whittaker ◽  
R. A. Chadwick
Keyword(s):  
Travel Time ◽  
Seismic Reflection ◽  
Large Scale ◽  
Large Scale Structure ◽  
Crystalline Basement ◽  
Scale Structure ◽  
Middle Zone ◽  
Lower Zone ◽  
Deep Seismic Reflection ◽  
Seismic Reflection Profiles

AbstractRecently acquired deep seismic reflection profiles recorded to 12 s two-way travel time in southern Britain suggest that the crust beneath this area is commonly divisible, vertically, into three zones.These zones, based upon seismic character, can be related to structural or tectonic units. They comprise an upper zone of cover rocks of various ages, a middle zone of folded and thrust rocks, and a lower zone tentatively identified as metamorphic or crystalline basement. A sketch crustal profile from Dorset to Yorkshire summarizes the data and illustrates the distribution of the zones.

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