scholarly journals Ore Geology, RE–OS Isotope Geochemistry of the Au and Au-Sb Mineralizations, Kular–Nera Terrane, Northeast Asia: Implications for Time of Formation and Ore Genesis

2021 ◽  
Vol 906 (1) ◽  
pp. 012011
Author(s):  
Valery Y. Fridovsky ◽  
Maxim Kudrin
Keyword(s):  
Late Jurassic ◽  
Gold Mineralization ◽  
Isotopic Ratio ◽  
Active Continental Margin ◽  
Northeast Asia ◽  
Volcanic Belt ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Upper Permian ◽  
Os Isotope

Abstract The paper presents the first results of investigation of the Re–Os isotope system of native gold from the Malo-Tarynskoe, Khangalas, Bazovskoe, and chalcopyrite from the Dvoinoe orogenic gold deposits and stibnite from the Maltan Au-Sb depositin the Kular–Nera terrane, Northeast Asia. The deposits are spatially related to NW-trending lithospheric-scale major brittle faults or controlled by subsidiary faults and fracture zones. Such zones served as pathways for fluids rising from below the crust, and they have a long tectonic and reactivation history. The Kular–Nera terrane consists of Upper Permian, Triassic, and Lower Jurassic clastic sedimentary-rock sequences, metamorphosed to initial stages of greenschist facies. Magmatism is manifested by Kimmeridgian–Berriasian S- and I-types granitoids and mafic dikes of the Tas–Kystabyt magmatic belt. Re concentration in gold varies from 0.168 to 6.997 ppb, and that of osmium – from 0.068 to 1.443 ppb. Chalcopyrite from the Dvoinoe deposit occurrence contains 0.1522 ppb Re and 0.499 ppb Os. Stibnite from the Maltan Au-Sb depositoccurrence contains 0. 236 ppb Re and 0.903 ppb Os. The Re–Os ages of gold from the Malo-Tarynskoe (147.8 ± 3.8 Ma) and Bazovskoe (147.2 ± 1.8 Ma) and Khangalas (137.1 ± 7.6 Ma) orogenic deposits and the Maltan Au-Sb deposits (69.7±1.9 Ma) are determined. Malo-Tarynskoe and Bazovskoe represent the earliest known orogenic gold mineralization in the Kular–Nera terrane. The data obtained permit us to correlate the initiation of orogenic gold-ore systems with the completion of the formation at the end of the Late Jurassic Uyandina–Yasachnaya volcanic belt, crystallization and subsequent cooling in the Late Jurassic–early Early Cretaceous of granitoid massifs of the Tas-Kystabyt magmatic belt, and subduction–accretionary events at the northeastern active continental margin of the Siberian craton. Maltan Au-Sb deposit is related to completion of the formation of the Albian-Late Cretaceous Okhotsk–Chukotka volcano-plutonic belt. Contrasting mantle and/or crustal sources of ore-forming material are established. The osmium initial isotopic ratio in gold 187Os/188Os = 0.2210-0.4275 and antimonite (0,2543-0,2976) is typical for the ore-forming material from the fertile mantle reservoir, and for chalcopyrite (3.1904) – from the crust.

A Tentative Study of Relationship between Mantle Plumes, Supercontinents and Orogenic Gold Deposits

2013 ◽  
Vol 734-737 ◽  
pp. 265-268
Author(s):  
Jun Hao Cui ◽  
Tao Ren
Keyword(s):  
Mantle Plume ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Upper Crust ◽  
Orogenic Gold Deposits ◽  
Orogenic Gold Deposit ◽  
The Earth ◽  
Tectonic Environment ◽  
The Relationship

On the basis of predecessors study, this paper found that outbreak frequency of mantle plume is increase, while scale is reduce. The mantle plume provides ore-forming minerals to orogenic gold deposits, as well as affords force to supercontinent formation and decomposition, for the more controls the global tectonic. Supercontinent is the movement of upper crust that could be cause by combine factors of cold and heat mantle plume. Supercontinent supply suitable tectonic environment for orogenic gold deposits. Further, we discuss the relationship between mantle plume, supercontinent and orogenic gold deposit on space and time. With the evolution of the earth, especially the energy loss, the frequency of orogenic gold mineralization is increasing, while the scale is reducing.

Gold-bismuth-telluride-sulphide assemblages at the Viceroy Mine, Harare-Bindura-Shamva greenstone belt, Zimbabwe

2008 ◽  
Vol 72 (4) ◽  
pp. 953-970 ◽  
Author(s):  
T. Oberthür ◽  
T. W. Weiser
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Close Association ◽  
Shear Zones ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Main Stage ◽  
Melting Temperatures ◽  
Native Bismuth ◽  
Gold Bearing

AbstractGold mineralization at the Viceroy Mine is hosted in extensional veins in steep shear zones that transect metabasalts of the Archaean Arcturus Formation. The gold mineralization is generally made up of banded or massive quartz carrying abundant coarse arsenopyrite. However, most striking is a distinct suite of Au-Bi-Te-S minerals, namely joseite-A (Bi4TeS2), joseite-B (Bi4Te2S), hedleyite (Bi7Te3), ikunolite (Bi4S3), ‘protojoseite’ (Bi3TeS), an unnamed mineral (Bi6Te2S), bismuthinite (Bi2S3), native Bi, native gold, maldonite (Au2Bi), and jonassonite (AuBi5S4). The majority of the Bi-Te-S phases is characterized by Bi/(Se+Te) ratios of >1. Accordingly, this assemblage formed at reduced conditions at relatively low fS2 and fTe2. Fluid-inclusion thermometry indicates depositional temperatures of the main stage of mineralization of up to 342°C, in the normal range of mesothermal, orogenic gold deposits worldwide. However, melting temperatures of Au-Bi-Te phases down to at least 235°C (assemblage (Au2Bi + Bi + Bi7Te3)) imply that the Au-Bi-Te phases have been present as liquids or melt droplets. Furthermore, the close association of native gold, native bismuth and other Bi-Te-S phases suggests that gold was scavenged from the hydrothermal fluids by Bi-Te-S liquids or melts. It is concluded that a liquid/melt-collecting mechanism was probably active at Viceroy Mine, where the distinct Au-Bi-Te-S assemblage either formed late as part of the main, arsenopyrite-dominated mineralization, or it represents a different mineralization event, related to rejuvenation of the shear system. In either case, some of the gold may have been extracted from pre-existing, gold-bearing arsenopyrite by Bi-Te-S melts, thus leading to an upgrade of the gold ores at Viceroy. The Au-Bi-Te-S assemblage represents an epithermal-style mineralization overprinted on an otherwise mesothermal (orogenic) gold mineralization.

scholarly journals Structural and dynamic conditions for the formation of large orogenic gold deposits in Central and Northeast Asia

LITOSFERA ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 349-364
Author(s):  
Yu. S. Savchuk ◽  
A. V. Volkov ◽  
V. V. Aristov
Keyword(s):  
Northeast Asia ◽  
Structural Features ◽  
Gold Deposits ◽  
Ore Deposits ◽  
Geological Mapping ◽  
Orogenic Gold ◽  
Migration Route ◽  
Orogenic Gold Deposits ◽  
Ore Mineralization ◽  
Volumetric Fracturing

Research subject. Large orogenic gold deposits in the fold belts of Central and Northeast Asia.Materials and methods. Geological mapping of various scales on a number of large orogenic gold deposits was conducted using the methods of structural-paragenetic analysis of metamorphic strata, accompanied by obligatory linking of ore mineralization manifestations to specific structures. In a number of cases, various statistical methods were used to geometrize mineralization, identify patterns of its location and determine the paths of paleofluid flows. Available publications on the objects under consideration were reviewed. The geological and structural features of large orogenic gold deposits – Muruntau, Kokpatas, Sukhoi Log and Pavlik – were considered.Results. The Muruntau, Kokpatas and the Sukhoi Log ore deposits are of shariyage-thrust type. Compared to these objects, the Pavlik field is confined to a zone of volumetric fracturing between a series of reverse faults, feathering a large deep fault and belonging to the transpression type. At the Muruntau and Pavlik deposits, the analysis of the location of the most intensive mineralization substantiated the paths of paleofluid flows, along which the fluid migration and ore formation took place.Conclusions. The distribution of ore mineralization in the Muruntau deposit obeys the orientation of planar (cleavage) and linear (orientation of fold hinges) elements. Apparently, the former (main) direction may indicate the orientation and position of the main migration route of ore-bearing fluids, while the latter corresponds to secondary channels, the position of which is due to the intersection of syn-napping structures with favourable lithological horizons. For the Pavlik deposit, the position of ore pillars is compared with the paths of paleofluid flows, the root parts of which are promising for identifying the most powerful and intense mineralization.

scholarly journals Genesis of the Koka Gold Deposit in Northwest Eritrea, NE Africa: Constraints from Fluid Inclusions and C-H-O-S Isotopes

2019 ◽  
Author(s):  
Kai Zhao ◽  
Huazhou Yao ◽  
Jianxiong Wang ◽  
Ghebsha Fitwi Ghebretnsae ◽  
Wenshuai Xiang ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Meteoric Water ◽  
Gold Mineralization ◽  
Early Stage ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Quartz Veins ◽  
Three Phase ◽  
Igneous Origin ◽  
Ne Africa

The Koka gold deposit is located in the Elababu shear zone between the Nakfa terrane and the Adobha Abiy terrane, NW Eritrea. Based on the paragenetic study two main stages of gold mineralization were identified in the Koka gold deposit: 1) an early stage of pyrite-chalcopyrite-sphalerite-galena-gold-quartz vein; and 2) a second stage of pyrite-quartz veins. NaCl-aqueous inclusions, CO2-rich inclusions, and three-phase CO2-H2O inclusions occur in the quartz veins at Koka. The ore-bearing quartz veins formed at 268℃, from NaCl-CO2-H2O(-CH4) fluids averaging 5 wt% NaCl eq. The ore-forming mechanisms include fluid immiscibility during stage I, and mixing with meteoric water during stage II. Oxygen, hydrogen and carbon isotopes suggest that the ore-forming fluids originated as mixtures of metamorphic water, meteoric water and magmatic water, whereas sulfur isotope suggest an igneous origin. Features of geology and ore-forming fluid at Koka deposit are similar to those of orogenic gold deposits, suggesting the Koka deposit might be an orogenic gold deposit related to granite.

scholarly journals Two Hydrothermal Events at the Shuiyindong Carlin-Type Gold Deposit in Southwestern China: Insight from Sm–Nd Dating of Fluorite and Calcite

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 230 ◽  
Author(s):  
Tan ◽  
Xia ◽  
Xie ◽  
Wang ◽  
Wei ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Gold Mineralization ◽  
Lower Triassic ◽  
Gold Deposits ◽  
Upper Permian ◽  
Southwestern China ◽  
Nd Isotope ◽  
T Values ◽  
Isotope Dating ◽  
Total Concentrations

The Shuiyindong Gold Mine hosts one of the largest and highest-grade, strata-bound Carlin-type gold deposits discovered to date in Southwestern China. The outcrop stratigraphy and drill core data of the deposit reveal Middle–Upper Permian and Lower Triassic formations. The ore is mainly hosted in Upper Permian bioclastic limestone near the axis of an anticline. The gold is mainly hosted in arsenian pyrite and arsenopyrite, mainly existing in the form of crystal lattice gold, submicroscopic particles and nanoparticles. Fluorite commonly occurs at the vicinity of an unconformity between the Middle–Upper Permian formations, which is proposed to be the structural conduit that fed the ore fluids. Calcite commonly fills fractures at the periphery of decarbonated rocks, which contain high grade orebodies. This study aimed to verify the occurrence of two distinct hydrothermal events at the Shuiyindong, based on Sm–Nd isotope dating of the fluorite and calcite. For this purpose, rare-earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm–Nd isochron ages of the fluorite and calcite were determined. The fluorite and calcite contain relatively high total concentrations of REE (12.3–25.6 μg/g and 5.71–31.7 μg/g, respectively), exhibit variable Sm/Nd ratios (0.52–1.03 and 0.57–1.71, respectively), and yield Sm–Nd isochron ages of 200.1 ± 8.6 Ma and 150.2 ± 2.2 Ma, with slightly different initial εNd(t) values of −4.4 and −1.1, respectively. These two groups of Sm–Nd isochron ages suggest two episodes of hydrothermal events at the Shuiyindong gold deposit. The age of the calcite probably represents the late stage of the gold mineralization period. The initial εNd(t) values of the fluorite and calcite indicate that the Nd was probably derived from mixtures of basaltic volcanic tuff and bioclastic limestone from the Permian formations.

Gold Deposits of the ~15-Moz Ahafo South Camp, Sefwi Granite-Greenstone Belt, Ghana: Insights into the Anatomy of an Orogenic Gold Plumbing System

2021 ◽  
Author(s):  
Quentin Masurel ◽  
Paul Morley ◽  
Nicolas Thébaud ◽  
Helen McFarlane
Keyword(s):  
Rock Mass ◽  
Shear Zone ◽  
Gold Mineralization ◽  
Hanging Wall ◽  
Spatial Association ◽  
Sedimentary Rocks ◽  
Shear Zones ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Plutonic Rocks

Abstract The ~15-Moz Ahafo South gold camp is located in southwest Ghana, the world’s premier Paleoproterozoic gold subprovince. Major orogenic gold deposits in the camp include Subika, Apensu, Awonsu, and Amoma. These deposits occur along an ~15-km strike length of the Kenyase-Yamfo shear zone, a major tectonostratigraphic boundary juxtaposing metamorphosed volcano-plutonic rocks of the Sefwi belt against metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé basin. In this study, we document the geologic setting, structural geometry, and rheological architecture of the Ahafo South gold deposits based on the integration of field mapping, diamond drill core logging, 3-D geologic modeling, and the geologic interpretation of aeromagnetic data. At the camp scale, the Awonsu, Apensu, and Amoma deposits lie along strike from one another and share similar hanging-wall plutonic rocks and footwall volcano-sedimentary rocks. In contrast, the Subika gold deposit is hosted entirely in hanging-wall plutonic rocks. Steeper-dipping segments (e.g., Apensu, Awonsu, Subika) and right-hand flexures (e.g., Amoma, Apensu) in the Kenyase-Yamfo shear zone and subsidiary structures appear to have represented sites of enhanced damage and fluid flux (i.e., restraining bends). All gold deposits occur within structural domains bounded by discontinuous, low-displacement, sinistral N-striking tear faults oblique to the orogen-parallel Kenyase-Yamfo shear zone. At the deposit scale, ore-related hydrothermal alteration is zoned, with distal chlorite-sericite grading into proximal silica-albite-Fe-carbonate mineral assemblages. Alteration halos are restricted to narrow selvages around quartz-carbonate vein arrays in multiple stacked ore shoots at Subika, whereas these halos extend 30 to 100 m away from the ore zones at Apensu and Awonsu. There is a clear spatial association between shallow-dipping mafic dikes, mafic chonoliths, shear zones, and economic gold mineralization. The abundance of mafic dikes and chonoliths within intermediate to felsic hanging-wall plutonic host rocks provided rheological heterogeneity that favored the formation of enhanced fracture permeability, promoting the tapping of ore fluid(s). Our interpretation is that these stacked shallow-dipping mafic dike arrays also acted as aquitards, impeding upward fluid flow within the wider intrusive rock mass until a failure threshold was episodically reached due to fluid overpressure, resulting in transient fracture-controlled upward propagation of the ore-fluid(s). Our results indicate that high-grade ore shoots at Ahafo South form part of vertically extensive fluid conduit systems that are primarily controlled by the rheological architecture of the rock mass.

Recycling of mercury from the atmosphere-ocean system into volcanic-arc–associated epithermal gold systems

Geology ◽  
2020 ◽  
Author(s):  
Changzhou Deng ◽  
Guangyi Sun ◽  
Yimeng Rong ◽  
Ruiyang Sun ◽  
Deyou Sun ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Marine Sediments ◽  
Northeast China ◽  
Active Continental Margin ◽  
Volcanic Belt ◽  
Gold Deposits ◽  
Ore Deposits ◽  
Epithermal Gold ◽  
Volcanic Arc ◽  
South China Craton

Photochemical processes generate mass-independent fractionation (MIF) of mercury (Hg) isotopes in the atmosphere-ocean system, and the subduction of marine sediments or hydrated oceanic crust may recycle the resultant Hg isotope signature into the volcanic-arc environment. This environment typically hosts epithermal gold deposits, which are characterized by a specific Hg-Sb-As metal association. We investigated the Hg isotopic composition of seven volcanic-arc–related epithermal gold deposits in northeast China and revisited the isotopic composition of Hg in hydrothermal ore deposits in circum-Pacific and Mediterranean volcanic arcs. The gold ore samples in northeast China mostly display positive Δ199Hg values (0.11‰ ± 0.07‰, 1σ, n = 48) similar to those observed in the Pacific Rim (0.07‰ ± 0.09‰, 1σ, n = 182) and the Mediterranean Cenozoic volcanic belt (0.09‰ ± 0.08‰, 1σ, n = 9). Because Hg in marine sediments and seawater has positive Δ199Hg, we infer that Hg-bearing epithermal deposits in active continental margin settings receive most Hg from recycled seawater in marine sediments, through the release of Hg by dehydration from the subducting oceanic slab. However, negative to near-zero Δ199Hg values were observed in Hg-bearing deposits in the South China craton (–0.09‰ ± 0.05‰, 1σ, n = 105) and in the intraplate magmatic-hydrothermal Almadén Hg deposit in Spain (–0.02‰ ± 0.06‰, 1σ, n = 26), which are considered to relate to basement and mantle sources, respectively. Hg isotopes have the potential to trace lithospheric Hg cycling.

scholarly journals Karakteristik Fluida Hidrotermal Endapan Emas Orogenik di Pegunungan Rumbia, Kabupaten Bombana, Provinsi Sulawesi Tenggara

2019 ◽  
Vol 20 (2) ◽  
pp. 111
Author(s):  
Hasria Hasria ◽  
Arifudin Idrus ◽  
I Wayan Warmada
Keyword(s):  
First Generation ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Salinity Range ◽  
Quartz Veins ◽  
The Third ◽  
Orogenic Gold Deposits ◽  
Gold Exploration ◽  
Calcite Veins

Recently, gold exploration activities  are not only focused along volcanic-magmatic belt but also starting to shift along metamorphicand sedimentary terrains. The purpose of this study is to analyses the characteristics hydrothermal fluids gold deposits t in the Rumbia Mountains, Bombana Regency, Southeast Sulawesi. There are three generations of veins identified including the first is parallel to the foliations, the second crosscuts the first generation of veins/foliations, and the third is of laminated deformed quartz+calcite veins at the late stage. Temperature of homogenization (Th) and salinity at Rumbia Mountain of the first vein vary from 220 to 355.30oC and 6.74 to 10.11 wt. % NaCl eq., respectively. The second generation vein was originated at Th of 157 to 255.50oC and salinity of 3.39 to 6.88 wt.%NaCl eq., whereas the third generation vein formed at lowest Th varying from 104.40 to 265.90oC and less saline fluid at salinity range between 0.18 and 6.30 wt.% NaCl eq. The result of temperature formation value correlation to the depth of the formation of orogenic gold deposits in Rumbia Mountain is indicated to form on sub-greenschist to greenschist facies at depth of about 4-8 kilometers and formation temperature between 104.40 - 355.30oC at zone epizonal and mesozonal. Based on characteristics fluids inclusion discussed above, the primary metamorphic-hosted gold mineralization type at Rumbia Mountain tends to meet the criteria of orogenic gold type.  Keyword : fluid iclusion, quartz veins, Rumbia mountain, orogenic gold deposits.

scholarly journals Genesis of the Koka Gold Deposit in Northwest Eritrea, NE Africa: Constraints from Fluid Inclusions and C–H–O–S Isotopes

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 201 ◽  
Author(s):  
Kai Zhao ◽  
Huazhou Yao ◽  
Jianxiong Wang ◽  
Ghebsha Fitwi Ghebretnsae ◽  
Wenshuai Xiang ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Gold Mineralization ◽  
Early Stage ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Quartz Veins ◽  
Second Stage ◽  
Three Phase ◽  
Igneous Origin ◽  
Ne Africa

: The Koka gold deposit is located in the Elababu shear zone between the Nakfa terrane and the Adobha Abiy terrane, NW Eritrea. Based on a paragenetic study, two main stages of gold mineralization were identified in the Koka gold deposit: (1) an early stage of pyrite–chalcopyrite–sphalerite–galena–gold–quartz vein; and (2) a second stage of pyrite–quartz veins. NaCl-aqueous inclusions, CO2-rich inclusions, and three-phase CO2–H2O inclusions occur in the quartz veins at Koka. The ore-bearing quartz veins formed at 268 °C from NaCl–CO2–H2O(–CH4) fluids averaging 5 wt% NaCl eq. The ore-forming mechanisms include fluid immiscibility during stage I, and mixing with meteoric water during stage II. Oxygen, hydrogen, and carbon isotopes suggest that the ore-forming fluids originated as mixtures of metamorphic water and magmatic water, whereas the sulfur isotope suggests an igneous origin. The features of geology and ore-forming fluid at the Koka deposit are similar to those of orogenic gold deposits, suggesting that the Koka deposit might be an orogenic gold deposit related to granite.

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