scholarly journals Disseminated Gold–Sulfide Mineralization in Metasomatites of the Khangalas Deposit, Yana–Kolyma Metallogenic Belt (Northeast Russia): Analysis of the Texture, Geochemistry, and S Isotopic Composition of Pyrite and Arsenopyrite

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 403
Author(s):  
Maxim V. Kudrin ◽  
Valery Yu. Fridovsky ◽  
Lena I. Polufuntikova ◽  
Lyudmila Yu. Kryuchkova
Keyword(s):  
Isotope Analysis ◽  
Distribution Patterns ◽  
Gold Deposits ◽  
Point Of View ◽  
Sulfide Mineralization ◽  
Northeast Russia ◽  
Metallogenic Belt ◽  
Two Generations ◽  
Computed Microtomography ◽  
Hydrothermal Sulfides

At the orogenic gold deposits of the Yana–Kolyma metallogenic belt (northeast Russia) both Au–quartz-sulfide mineralization with native gold and disseminated sulfide mineralization with invisible Au developed. The textural and mineralogical-geochemical features, isotope-geochemical characteristics of gold-bearing sulfides from proximal metasomatites, and possible forms of Au occurrence in pyrite and arsenopyrite have been studied using electron microprobe, atomic absorption, LA-ICP-MS trace element, isotope analysis, and computed microtomography. Four generations of pyrite (Py1, diagenetic; Py2, metamorphic; Py3, metasomatic; Py4, veined) and two generations of arsenopyrite (Apy1, metasomatic; Apy2, veined) have been identified at the Khangalas deposit. In the proximal metasomatites, the most common are Py3 and Apy1. Studying their chemical composition makes it possible to identify the features of the distribution patterns of typochemical trace elements in pyrite and arsenopyrite, and to establish the nature of the relationship between Au and these elements. In Py3 and Apy1, structurally bound (solid solution) Au+ prevails, isomorphically entering the crystal lattice or its defects. Isotope characteristics of hydrothermal sulfides (d34S = –2.0 to –0.6‰) indicate that mantle/magmatic sulfur was involved in the formation of the deposit, though the participation of sulfur from the host rocks of the Verkhoyansk clastic complex cannot be ruled out. The Khangalas deposit has much in common with other gold deposits of the Yana–Kolyma metallogenic belt, and from this point of view, the results obtained will help to better reveal their gold potential and understand their origin.

scholarly journals AGE OF GOLD MINERALIZATION IN THE YANA-KOLYMA METALLOGENIC BELT, NORTHEAST RUSSIA: FIRST DATA OF RE-OS ISOTOPE GEOCRONOLOGY OF NATIVE GOLD

2021 ◽  
Vol 40 (4) ◽  
pp. 18-32
Author(s):  
V.Yu. Fridovsky ◽  
◽  
N.А. Goryachev ◽  
R.Sh. Krymsky ◽  
M.V. Kudrin ◽  
...  
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Northeast Russia ◽  
Metallogenic Belt ◽  
Mantle Sources ◽  
First Results ◽  
Isotope System ◽  
Os Isotope

Presented are the first results of studying the Re-Os isotope system of native gold from the orogenic Malo-Taryny, Khangalas, and Bazovsky deposits located in the central part of the Yana-Kolyma metallogenic belt. Re concentration in the sampled gold varies from 0.168 to 6.997 mg/t while that of Os changes from 0.068 to 1.443 mg/t. The data obtained enabled calculation of the isochrone age which is consistent, within the limits of error, with 40Ar-39Ar and К-Аr dates of sericite from the above deposits. The results obtained indicate that gold deposits under study were formed in the interv of 147.8–137.1 Ma synchronously with Late Jurassic – Early Cretaceous orogenic processes in the Yana-Kolyma metallogenic belt and the eastern margin of the Siberian continent. The initial Os isotope ratios ((187Os/188Os)i= 0.1844–0.2475) in the studied samples and fractions of gold from the Malo-Tarynsky, Khangalas and Bazovsky deposits suggest a significant role of a non-radiogenic component, normally associated with mantle sources.

scholarly journals On Apogamy and the development of Sporangia upon fern prothalli

1898 ◽  
Vol 63 (389-400) ◽  
pp. 56-61
Keyword(s):  
Life History ◽  
Point Of View ◽  
The Other ◽  
Normal Life ◽  
Other Hand ◽  
General Importance ◽  
Two Generations ◽  
History Of ◽  
Alternation Of Generations

The two most important deviations from the normal life-history of ferns, apogamy and apospory, are of interest in themselves, but acquire a more general importance from the possibility that their study may throw light on the nature of alternation of generations in archegoniate plants. They have been considered from this point of view Pringsheim, and by those who, following him, regard the two generations as homologous with one another in the sense that the sporophyte arose by the gradual modification of individuals originally resemblin the sexual plant. Celakovsky and Bower, on the other hand, maintaint the view tha t the sporophyte, as an interpolated stage in the life-history arising by elaboration of the zygote, a few thallophytes.

scholarly journals Generations Comparison: Father Role Representations in the 1980s and the New Millennium

Genealogy ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 17 ◽  
Author(s):  
Maria Letizia Bosoni ◽  
Sara Mazzucchelli
Keyword(s):  
Point Of View ◽  
Current Debate ◽  
The Social ◽  
Two Generations ◽  
Academic Publications ◽  
Research Questions ◽  
Father Role ◽  
Changing Role ◽  
New Millennium

In the light of relevant and current debate on the changing role of fathers, this contribution is aimed at analysing the international literature on fatherhood, comparing two distinct periods of time, from the social, cultural and demographic point of view: the years 1980–1999 and the new millennium. This will contribute to identifying features of the fatherhood transformation in these two contexts, which in fact refer to two generations of fathers. The research questions to be answered are: Which aspects characterize the process of fatherhood transformation, in an intergenerational perspective? How are paternal childcare practices represented in different historical and social periods? An analysis of the academic publications on fathers in Scopus and Google Scholar will be conducted, in the two temporal periods indicated, using T-Lab software, in order to map fathers’ role representations.

scholarly journals Origin of the Shangfang Tungsten Deposit in the Fujian Province of Southeast China: Evidence from Scheelite Sm–Nd Geochronology, H–O Isotopes and Fluid Inclusions Studies

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 713 ◽  
Author(s):  
Lü-Yun Zhu ◽  
Shao-Yong Jiang ◽  
Run-Sheng Chen ◽  
Ying Ma
Keyword(s):  
Fluid Inclusions ◽  
Large Scale ◽  
Tectonic Setting ◽  
Critical Role ◽  
Isotope Analysis ◽  
Western Boundary ◽  
Ionization Mass ◽  
Tungsten Deposit ◽  
Nanling Range ◽  
Metallogenic Belt

The Shangfang deposit is a recently discovered large-scale tungsten deposit (66,500 t at 0.23% WO3), which is located near the western boundary of the Southeastern Coastal Metallogenic Belt (i.e., Zhenghe–Dafu fault), and adjacent to the northeast of the Nanling Range Metallogenic Belt. Unlike many other W–Sn deposits in this region that occur within or near the granites, the orebodies in the Sangfang deposit all occur within the amphibolite of Palaeoproterozoic Dajinshan Formation and have no direct contact to the granite. In this study, we carry out a thermal ionization mass spectrometer (TIMS) Sm-Nd isotope analysis for the scheelites from the orebody, which yields a Sm–Nd isochron age of 157.9 ± 6.7 Ma (MSWD = 0.96). This age is in good agreement with the previously published zircon U–Pb age (158.8 ± 1.6 Ma) for the granite and the molybdenite Re–Os age (158.1 ± 5.4 Ma) in the deposit. Previous studies demonstrated that the W–Sn deposits occurring between Southeastern Nanling Range and Coastal Metallogenic Belt mainly formed in the two periods of 160–150 Ma and 140–135 Ma, respectively. The microthermometry results of fluid inclusions in scheelite and quartz are suggestive of a near-isothermal (possibly poly-baric) mixing between two fluids of differing salinities. The H–O isotope results illustrate that the ore-forming fluids are derived from magma and might be equilibrated with metamorphic rocks at high temperature. The Jurassic granite pluton should play a critical role for the large hydrothermal system producing the Shangfang W deposit. Furthermore, the negative εNd(t) of −14.6 obtained in the Shanfang scheelite suggests for the involvement of the deep crustal materials. In general, subduction of the paleo-Pacific plate caused an extensional tectonic setting with formation of the Shangfang granites and related W mineralization, the geological background of which is similar to other W deposits in the Nanling Range Metallogenic Belt.

Rational Methods of Concentration of Small, Thin, Finely Dispersed and Colloidal Gold of Technogenic Waste Deposits Will Ryveem

2018 ◽  
Vol 22 (10) ◽  
pp. 11-17 ◽  
Author(s):  
V.V. Karmazin ◽  
I.O. Krylov ◽  
P.A. Sysa ◽  
M.A. Frolov
Keyword(s):  
Rock Mass ◽  
Colloidal Gold ◽  
Energy Efficient ◽  
Low Frequency ◽  
Gold Deposits ◽  
Point Of View ◽  
Efficient Technology ◽  
Theoretical Substantiation ◽  
Technogenic Waste ◽  
Energy Efficient Technology

The potential of the ore-bearing territory and the dumps of the former mine placed on it are estimated from the point of view of application of new technological solutions that will allow to process the man-made rock mass profitably. The nature of the distribution of gold by size classes is established, which can significantly reduce the volume of processed rock mass. Theoretical substantiation of acceleration of natural segregation with application of low-frequency sound influence is given. The segregation-diffusion concentration of gold is proposed, which allows in the future to create an energy-efficient technology of recovery from man-made waste and apply it to the processing of gold deposits still in the depths.

K-Ar, δ18O and REE constraints on the genesis of ammonium illite from the Harghita Bãi hydrothermal system, Romania

Clay Minerals ◽  
2010 ◽  
Vol 45 (3) ◽  
pp. 393-411 ◽  
Author(s):  
N. Clauer ◽  
N. Liewig ◽  
I. Bobos
Keyword(s):  
First Generation ◽  
Distribution Patterns ◽  
Hydrothermal Activity ◽  
Precipitation Process ◽  
New Information ◽  
Eastern Carpathians ◽  
Elemental Analyses ◽  
Two Generations ◽  
Mixed Layers ◽  
New Generation

AbstractAmmonium illite and ammonium illite-smectite mixed layers, together with potassium illite, smectite and minute amounts of kaolinite were identified in hydrothermally altered andesite rocks from the Harghita Bãi area of the Eastern Carpathians, Romania. K-Ar dating and oxygen isotope tracing, as well as rare-earth elemental analyses were made to provide new information on the timing and crystal-chemical processes characterizing the crystallization and further evolution of these illite-type mineral phases.The combined results suggest the occurrence of hydrothermal activity in two distinct episodes with nucleation of two generations of illite-type particles of different chemistry and morphology. About 9.5 Ma ago, potassium illite crystallized in alteration halos of the porphyry Cu system, probably at a temperature of ~270ºC from fluids having a δ18O of ~2.9% (V-SMOW). Associated smectite seems to have precipitated slightly later in external alteration halos at a similar temperature, but from fluids depleted in alkalis and with a different δ18O. Alternately, ammonium-rich illite-smectite mixed layers formed very recently, less than ~1 million years ago at a temperature of ~90ºC from fluids of probable meteoric origin that altered the previously crystallized potassium illite, resulting in the crystallization of a new generation of ammonium illite-smectite mixed layers. Evidence of this dissolution-precipitation process is provided by a significant increase in the δ18O of the mixed-layer structures and by a significant change in their REE contents and distribution patterns. Occurrence of potassium in the ammonium-rich mixed layers probably relates to the progressive alteration of the first-generation potassium illite and a discrete concomitant take up of released K by the new NH4-rich interlayers of the ammonium mixed layered sequence.

scholarly journals Tourmaline from Late Quartz Veins of the Murtykty Gold Deposit, Republic of Bashkortostan

2020 ◽  
Vol 6 (1) ◽  
pp. 69-83
Author(s):  
M.A. Rassomakhin ◽  
E.V. Belogub ◽  
K.A. Novoselov ◽  
P.V. Khvorov
Keyword(s):  
Gold Deposit ◽  
Sedimentary Rocks ◽  
Gold Deposits ◽  
Sulfide Mineralization ◽  
Porphyry Deposits ◽  
Quartz Veins ◽  
Orogenic Gold Deposits ◽  
Eastern Zone ◽  
Republic Of Bashkortostan ◽  
Intermediate Member

Tourmaline, an intermediate member of the oxyschorl–oxydravite–oxymagnesio-foitite-bosiite series with a predominance of the oxy-dravite-bosiite end-member, was studied from late calcite-quartz veins in the eastern zone of the Murtykty gold deposit (Republic of Bashkortostan). Sulfide mineralization in veins includes rare chalcopyrite, pyrite, sphalerite and galena. Accessory minerals are xenotime-(Y), vanadium-containing rutile and fine high-fineness gold. Supergene mineralization resulted from decomposition of carbonates, sulfides and rock-forming silicates includes kaolinite, hydroxides of Mn (chalcophanite, psilomelane) and Fe (goethite and limonite ochers), mainly developed in vein cavities ; chalcopyrite is replaced by cuprite and malachite. The composition of tourmaline is close to metamorphic dravite of orogenic gold deposits and tourmaline of gold-porphyry deposits, transitioning from porphyry to epithermal. Two possible B sources for the formation of tourmaline are considered: sedimentary rocks of the paleoisland-arc complex and granodiorites of the Mansurovo pluton. Figures 9. Table 1. References 36. Key words: tourmaline, boron, gold, xenotime-(Y), Murtykty deposit, Republic of Bashkortostan.

scholarly journals Multistages mineralization and transformation of terrigenous rocks in the Vyun ore field, Yana-Kolyma metallogenic belt, Northeast Asia: insight from the sedimentary, diagenetic and hydrothermal sulfides and geochemistry of ore-hosting rocks

2021 ◽  
Vol 906 (1) ◽  
pp. 012041
Author(s):  
Lena Polufuntikova ◽  
Valery Fridovsky ◽  
Yaroslav Tarasov ◽  
Maksim Kudrin
Keyword(s):  
Trace Elements ◽  
Middle Jurassic ◽  
Chemical Elements ◽  
Northeast Asia ◽  
Upper Triassic ◽  
Terrigenous Rocks ◽  
Metallogenic Belt ◽  
Oxygen Conditions ◽  
Hydrothermal Sulfides ◽  
Epigenetic Processes

Abstract The article presents the results of studying the sulfidization zone of the Charky-Indigirka thrust fault within the Vyun ore field in the Upper Adycha sector of the Yana-Kolyma metallogenic belt. The purpose of the research is to study the composition and distribution of basic and trace elements in terrigenous rocks of the Upper Triassic and Middle Jurassic, as well as in distal metasomatites on the territory of the Vyun ore field. The petrochemical features of weakly altered terrigenous rocks, conditions of their formation and changes of composition during epigenetic processes were analyzed. Three generations of pyrite were identified: diagenetic Py1, metamorphogenic Py2 and metasomatic Py3. Typomorphic trace elements and variations of their distribution in pyrites were determined. Composition analyses of weakly altered sedimentary rocks of the Upper Triassic (V/(V+Ni)=0.5-0.8, V/Cr=0.1-2.9 and Ni/Co=2.5-10.3) and Middle Jurassic (V/(V+Ni)=0.7-0.9, V/Cr=0.2-2.0 and Ni/Co=1.3-8.8) yielded the conclusion that changes in oxygen conditions to disoxic and anoxic, as well as the enrichment of terrigenous material with ore elements, lead to the formation of authigenic sulfide mineralization at the early stages of the sedimentary strata formation. The subsequent multistage development of the territory was accompanied by an active migration of chemical elements, their input and redistribution.

scholarly journals Mineralization and Structural Controls of the AB-Bid Carbonate-Hosted Pb-Zn (±Cu) Deposit, Tabas-Posht e Badam Metallogenic Belt, Iran

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 95
Author(s):  
Abdorrahman Rajabi ◽  
Carles Canet ◽  
Pura Alfonso ◽  
Pouria Mahmoodi ◽  
Ali Yarmohammadi ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Structural Data ◽  
Wall Rock ◽  
Fault System ◽  
Current Evidence ◽  
Mining District ◽  
Sulfur Source ◽  
Reverse Fault ◽  
Sulfide Mineralization ◽  
Metallogenic Belt

The Ab-Bid deposit, located in the Tabas-Posht e Badam metallogenic belt (TPMB) in Central Iran, is the largest Pb-Zn (±Cu) deposit in the Behadad-Kuhbanan mining district. Sulfide mineralization in the Ab-Bid deposit formed in Middle Triassic carbonate rocks and contains galena and sphalerite with minor pyrite, chalcopyrite, chalcocite, and barite. Silicification and dolomitization are the main wall-rock alteration styles. Structural and textural observations indicate that the mineralization occurs as fault fills with coarse-textured, brecciated, and replacement sulfides deposited in a bookshelf structure. The Ab-Bid ore minerals precipitated from high temperature (≈180–200 °C) basinal brines within the dolomitized and silicified carbonates. The sulfur isotope values of ore sulfides suggest a predominant thermochemical sulfate reduction (TSR) process, and the sulfur source was probably Triassic-Jurassic seawater sulfate. Given the current evidence, mineralization at Ab-Bid resulted from focusing of heated, over-pressurized brines of modified basinal origin into an active fault system. The association of the sulfide mineralization with intensely altered wall rock represents a typical example of such features in the Mississippi Valley-type (MVT) metallogenic domain of the TPMB. According to the structural data, the critical ore control is a bookshelf structure having mineralized dextral strike-slip faults in the northern part of the Ab-Bid reverse fault, which seems to be part of a sinistral brittle shear zone. Structural relationships also indicate that the strata-bound, fault-controlled Ab-Bid deposit was formed after the Middle Jurassic, and its formation may be related to compressive and deformation stages of the Mid-Cimmerian in the Middle Jurassic to Laramide orogenic cycle in the Late Cretaceous-Tertiary.

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