Reworking intensity—A key factor leading to the formation of superlarge gold deposits in greenstone belts and metamorphosed microclastic rocks in China

1999 ◽  
Vol 18 (4) ◽  
pp. 289-297
Author(s):  
Xiuzhang Wang ◽  
Defu Lu ◽  
Jingping Cheng ◽  
Hanlong Ying ◽  
Huaying Liang ◽  
...  
Keyword(s):  
Gold Deposits ◽  
Key Factor ◽  
Greenstone Belts

Chapter 33: Neoarchean Eastern Goldfields of Western Australia

2020 ◽  
pp. 709-734
Author(s):  
Gerard I. Tripp ◽  
Richard M. Tosdal ◽  
Thomas Blenkinsop ◽  
Jamie R. Rogers ◽  
Scott Halley
Keyword(s):  
Western Australia ◽  
Spatial Association ◽  
Shear Zones ◽  
Gold Deposits ◽  
Gold Deposition ◽  
Structural Environment ◽  
World Class ◽  
Greenstone Belts ◽  
Crustal Shear Zones ◽  
Host Rocks

Abstract Neoarchean greenstone-hosted gold deposits in the Eastern Goldfields Superterrane of the Yilgarn craton of Western Australia are diverse in style, timing with respect to magmatic activity, structural environment, host rocks, and geochemical character. Geologic constraints for the range of gold deposits indicate deposit formation synchronous with volcanism, synchronous with syn- and postvolcanic intrusion, synchronous with postvolcanic deformation in faults and shear zones, or some combination of superposed events over time. The gold deposits are distributed as clusters along linear belt-parallel fault zones internal to greenstone belts but show no association with major terrane boundary faults. World-class gold districts are associated with the thickest, internal parts of the greenstone belts identified by stratigraphic preservation and low metamorphic grades. Ore-proximal faults in those regions are more commonly associated with syn- and postvolcanic structures related to greenstone construction and deformation rather than major terrane amalgamation. Using the Kalgoorlie district as a template, the gold deposits show a predictable regional association with thicker greenstone rocks overlain unconformably by coarse clastic rock sequences in the uppermost units of the greenstone stratigraphy. At a camp scale, major gold deposits show a spatial association with unconformable epiclastic and volcaniclastic rocks located above an unconformity internal to the Black Flag Group. Distinct episodes of gold deposition in coincident locations suggest fundamental crustal structural controls provided by the fault architecture. Late penetrative deformation and metamorphism overprinted the greenstone rocks and the older components of many gold deposits and were accompanied by major gold deposition in late quartz-carbonate veins localized in crustal shear zones or their higher order fault splays.

ORE-MAGMATIC SYSTEM SUKUMALAND (TANZANIA)

2019 ◽  
pp. 34-41
Author(s):  
V. Mykhailov
Keyword(s):  
Lake Victoria ◽  
Volcanic Rocks ◽  
Structural Features ◽  
Gold Deposits ◽  
Northwestern Part ◽  
Magmatic System ◽  
Metallogenic Province ◽  
Greenstone Belts ◽  
Basic Volcanic ◽  
Ore Potential

The overwhelming part of the gold ore potential of the United Republic of Tanzania is confined to the systems of the Neoarchaean greenstone belts (GSB) of the metallogenic province of Lake Victoria in the northwestern part of the country. Based on the interpretation of space imagery, in the western part of the province the Sukumaland ore-magmatic system of concentric-zonal structure has been distinguished. It is formed by a group of arched greenstone belts and associated gold deposits. They form two arcuate branches: the internal and external branch, differing in their composition and structure. The internal arc is represented by the Rwamagaza and Kahama GSB with gold deposits of Tulawaka, Buckreef, Mawe-Meru, Tembo, and Bulyanhulu. The external arc is represented by Geita and Mabale-Buhungurica GSB with gold deposits of Ridge-8, Nyankanga, Geita, Matandani, Kukuluma, Nyanzaga, Kitongo, Golden Ridge, Nyakafuru, and Miabu. Their huge gold potential (over 50 million ounces of gold) stipulates for the urgency of the study of this gigantic structure. GSB of the inner arc (Rwamagaza and Kahama) are characterized by a predominance of basic volcanic rocks, and GSB of the external arc (Geita and Mabale-Buhungurica) – by sedimentary and volcanic-sedimentary formations, in particular, banded ironstone formations (BIF). Accordingly, gold deposits of the inner arc are mainly associated with basic volcanic rocks (Tulawaka, Buckreef, Mawe-Meru, Bulyanhulu, Tembo) while gold deposits of the external arc – with BIF (Geita, Nyankanga, Kukuluma, Matandani). The nuclear part of the ore-magmatic system is of special interest, although manifestations of volcanism are absent there and gold or other mineral deposits are unknown yet, but a tectonic pattern of its structural elements indicates its significant ore potential. In particular, the presence of numerous spatially close systems of radial-circular faults attests to the presence of weakened zones in the space above the core of a hypothetical magma chamber. Gold deposits of different geological and industrial types, yet undiscovered, as well as manifestations of diatreme magmatism may be associated with these weakened zones. In particular, one cannot exclude the possible presence of diamond-bearing volcanic pipes. It is assumed that the ore-magmatic system has originated and evolved in the course of a complex multi-stage ore-magmatic process under the influence of ascending flows of depth fluids due to the long-term functioning of a zone with anomalously heated mantle in that area. During further geological exploration it is recommended to take into account the predictable availability of a single integrated ore-magmatic system of longdevelopment and its structural features.

scholarly journals Gold deposits of Suriname: geological context, production and economic significance

2016 ◽  
Vol 95 (4) ◽  
pp. 429-445 ◽  
Author(s):  
Nicole M. E. Kioe-A-Sen ◽  
Manfred J. van Bergen ◽  
Theo E. Wong ◽  
Salomon B. Kroonenberg
Keyword(s):  
Greenstone Belt ◽  
Gold Deposits ◽  
Point Of View ◽  
Open Pit ◽  
Small Scale ◽  
Ore Formation ◽  
Economic Significance ◽  
History Of ◽  
Greenstone Belts ◽  
Available Information

AbstractGold has been a major economic asset for Suriname for more than a century. The long history of gold mining, concentrated in large parts of a greenstone belt in the northeast of the country, began with small-scale artisanal extraction activities and has recently seen the development of major open-pit operations. Despite the range of mining activities, Suriname's gold deposits and occurrences are under-explored from a scientific point of view. Primary gold mineralisations in the greenstone belt occur in multiple forms, and although their origin is commonly related to the Palaeoproterozoic Trans-Amazonian orogeny, the controls of ore formation in specific cases often remain obscure. This contribution presents an abridged overview of currently available information on the geological setting and characteristics for some of the main deposits where gold is extracted. In view of the consistent link between gold metallogeny and granitoid–greenstone belts in the northern Guiana Shield, the mineralised settings in Suriname are discussed in a regional context.

scholarly journals Intrusion-Associated Gold Systems and Multistage Metallogenic Processes in the Neoarchean Abitibi Greenstone Belt

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 261
Author(s):  
Lucie Mathieu
Keyword(s):  
Greenstone Belt ◽  
Gold Deposits ◽  
Hydrothermal Systems ◽  
Magmatic Fluid ◽  
Gold Deposition ◽  
Alkaline Magmatism ◽  
Abitibi Greenstone Belt ◽  
Metamorphic Fluids ◽  
Greenstone Belts ◽  
Gold Bearing

In gold-endowed greenstone belts, ore bodies generally correspond to orogenic gold systems (OGS) formed during the main deformation stage that led to craton stabilization (syntectonic period). Most OGS deposits postdate and locally overprint magmatic-hydrothermal systems, such as Au-Cu porphyry that mostly formed during the main magmatic stage (synvolcanic period) and polymetallic intrusion-related gold systems (IRGS) of the syntectonic period. Porphyries are associated with tonalite-dominated and sanukitoid plutons, whereas most IRGS are related to alkaline magmatism. As reviewed here, most intrusion-associated mineralization in the Abitibi greenstone belt is the result of complex and local multistage metallogenic processes. A new classification is proposed that includes (1) OGS and OGS-like deposits dominated by metamorphic and magmatic fluids, respectively; (2) porphyry and IRGS that may contain gold remobilized during subsequent deformation episodes; (3) porphyry and IRGS that are overprinted by OGS. Both OGS and OGS-like deposits are associated with crustal-scale faults and display similar gold-deposition mechanisms. The main difference is that magmatic fluid input may increase the oxidation state and CO2 content of the mineralizing fluid for OGS-like deposits, while OGS are characterized by the circulation of reduced metamorphic fluids. For porphyry and IRGS, mineralizing fluids and metals have a magmatic origin. Porphyries are defined as base metal and gold-bearing deposits associated with large-volume intrusions, while IRGS are gold deposits that may display a polymetallic signature and that can be associated with small-volume syntectonic intrusions. Some porphyry, such as the Côté Gold deposit, demonstrate that magmatic systems can generate economically significant gold mineralization. In addition, many deposits display evidence of multistage processes and correspond to gold-bearing or gold-barren magmatic-hydrothermal systems overprinted by OGS or by gold-barren metamorphic fluids. In most cases, the source of gold remains debated. Whether magmatic activity was essential or marginal for fertilizing the upper crust during the Neoarchean remains a major topic for future research, and petrogenetic investigations may be paramount for distinguishing gold-endowed from barren greenstone belts.

scholarly journals Criteria for the recognition of Archean calc-alkaline lamprophyres: examples from the Abitibi Subprovince

2018 ◽  
Vol 55 (2) ◽  
pp. 188-205 ◽  
Author(s):  
Lucie Mathieu ◽  
Émile Bouchard ◽  
Francis Guay ◽  
Alizée Liénard ◽  
Pierre Pilote ◽  
...  
Keyword(s):  
Mineral Exploration ◽  
Gold Deposits ◽  
Chemical Analyses ◽  
Calc Alkaline ◽  
Thin Sections ◽  
Mafic Intrusions ◽  
Abitibi Subprovince ◽  
Greenstone Belts ◽  
Archean Greenstone Belts ◽  
Alkaline Lamprophyres

Lamprophyres are minor intrusions with atypical sources and crystallisation sequences. Among lamprophyres, the calc-alkaline (CAL) type on which this study focuses has the least distinctive chemistry and petrology. CAL correspond to small-volume mafic intrusions characterised by the early fractionation of amphibole and (or) biotite. In the Archean Superior Province (Canada), CAL are temporally and spatially related to several gold deposits and may thus be relevant to mineral exploration. This study focuses on several altered and metamorphosed intrusions of the Abitibi and La Grande subprovinces, which were designated lamprophyres based on field observations. Several criteria established from thin sections, whole-rock chemical analyses, and SEM data are applied to the studied rocks to distinguish CAL from other types of magma. As a result, only one of the studied dykes has the morphology, chemistry, and petrology typical of CAL, while the other intrusions are either too altered to be classified or may correspond to metamorphosed and metasomatized gabbro and diorite. This study shows that thin sections and whole-rock chemical analyses are not always sufficient to unequivocally classify an altered and metamorphosed intrusion as a CAL. Also, intrusions as challenging to recognise as CAL should not be used by exploration geologists to prospect for orogenic gold deposits. Much remains to be done to document the distribution and volume represented by lamprophyres in Archean greenstone belts and to confirm their spatial dependence with gold deposits.

scholarly journals Gold Prospects in the Western Segment of the Russian Arctic: Regional Metallogeny and Distribution of Mineralization

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 137 ◽  
Author(s):  
Arkady Kalinin ◽  
Oleg Kazanov ◽  
Vladimir Bezrukov ◽  
Vsevolod Prokofiev
Keyword(s):  
Gold Mineralization ◽  
Regional Scale ◽  
Gold Deposits ◽  
Fennoscandian Shield ◽  
Amphibolite Facies ◽  
Southern Boundary ◽  
The North ◽  
Tectonic Zones ◽  
Western Segment ◽  
Greenstone Belts

Location of the deposits and occurrences of gold mineralization in metamorphic complexes of the Kola region is controlled by tectonic zones at the regional scale at the boundaries of major segments of the Fennoscandian Shield. Three zones are the most important: (1) the system of Neoarchean greenstone belts Kolmozero–Voron’ya–Ura-guba along the southern boundary of the Murmansk craton; (2) the suture, delineating the core of the Lapland–Kola orogeny in the north; and (3) the series of overthrusts and faults at the eastern flank of the Salla–Kuolajarvi belt. Gold deposits and occurrences are located within greenstone belts of Neoarchean and Paleoproterozoic age, and hosted by rocks of different primary compositions (mafic metavolcanics, diorite porphyry, and metasedimentary terrigenous rocks). The grade of metamorphism varies from greenschist to upper amphibolite facies, but the mineralized rocks are mainly lower amphibolite metamorphosed, close to the transition from greenschist to amphibolite facies. Gold deposits and occurrences in the northeastern part of the Fennoscandian Shield formed during two periods: the Neoarchean 2.7–2.6 Ga and the Paleoproterozoic 1.9–1.7 Ga. According to paleo-geodynamic reconstructions, these were the periods of collisional and accretionary orogeny in the region. Those Archean greenstone belts, which were reworked in the Paleoproterozoic (e.g., Strel’na and Tiksheozero belts), can contain gold deposits of Paleoproterozoic age.

scholarly journals COMPLEX GOLD-MOLYBDENUM DEPOSITS AND OCCURRENCES IN GREENSTONE BELTS OF THE MIDDLE DNIPRO REGION OF THE UKRAINIAN SHIELD

2018 ◽  
pp. 3-9 ◽  
Author(s):  
V. V. Sukach ◽  
L. O. Riazantseva
Keyword(s):  
Gold Mineralization ◽  
Gold Deposits ◽  
The West ◽  
Gold Ores ◽  
Related Research ◽  
Geological Surveys ◽  
Technical Base ◽  
Greenstone Belts ◽  
Generating System ◽  
Geological Research

The most important molybdenum mineralization of the Middle Dnipro province is limited to the Mesoarchean (3,1–2,9 Ga) Greenstone belts or structure (GSS). These are next occurrences: East-Sergiivka, Solone in the Sura GSS and Gannivka (district “Chervona”) in the Kryvyi Rih GSS. They have spatial combining or closeness with well-known gold deposits and occurrences: East-Sergiivka and Solone occurrences are located on the Eastern flanks of the Sergiivka and Balka Zolota deposits, respectively, in the sublatitudinal ore-bearing zones. From the West to the East gold mineralization gradually changes to gold-molybdenum and molybdenum. Gannivka molybdenum and Zhovtіanka gold occurrences are adjacent and localized in the submeridional zone of the Kryvyi Rih-Kremenchuk fault, and not spatially combined. However, similar to the etalon Lobash deposit, they can be combined as elements of a common ore-generating system related to a submeridional-extended granite massif undiscovered by erosion. In the process of previously performed geological surveys and related research, these ore prospects were studied and evaluated separately for each type of minerals. It is proposed to carry out further geological research in the context of spatially and genetically combining of gold and molybdenum mineralization. First of all it concerns deposits and occurrences of Sura GSS, where it is rationally to place two complex gold-molybdenum deposits: Sergiivka and Balka Zolota. This approach, which involves carrying out mining and exploration works on a joint scientific and technical base for molybdenum and gold ores, will undoubtedly have good economic efficiency and, ultimately, substantially increase the investment attractiveness of one or another deposit, facilitate the early launch industrial exploitation.

Gold deposits ot the Guiana shield

2021 ◽  
pp. 4-10
Author(s):  
Alexey Maslovsky
Keyword(s):  
Comparative Analysis ◽  
Gold Deposits ◽  
Guiana Shield ◽  
The Past ◽  
Lower Proterozoic ◽  
Geological Features ◽  
Greenstone Belts ◽  
Almost All

The article provides a comparative analysis of Guyana and Venezuela major deposits within the Quartzstone ore field (Guyana). From the northwest to the southeast (from Venezuela to Brazil), more than 10 ore gold deposits are currently known, their total resources (including previous production) exceed 2,600 tons of gold (excluding the Amapari and Salamangoni deposits in Brazil). Almost all of Guyana deposits are confined to the Lower Proterozoic greenstone belts of the Guiana shield identified and explored for the past 15–20 years. The geological features of the largest deposits (Omay, Aurora, Toroparu, Tassawini and Monosi) are presented in the article.

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