Paragenesis of gold mineralization at the Kiyuk Lake Project, Kivalliq Region, Nunavut, Canada

2021 ◽  
Vol 59 (5) ◽  
pp. 1133-1165
Author(s):  
Stacie Jones ◽  
Kurt Kyser ◽  
Matthew Leybourne ◽  
Robin Mackie ◽  
Adrian Fleming ◽  
...  
Keyword(s):  
Gold Mineralization ◽  
Sedimentary Rocks ◽  
Normal Fault ◽  
Canadian Shield ◽  
The North ◽  
Calcic Amphibole ◽  
Greenstone Belts ◽  
Clastic Sedimentary ◽  
Archean Greenstone Belts ◽  
Hurwitz Group

ABSTRACT Exploration for gold in Nunavut has been primarily focused on Archean greenstone belts in the north and coastal regions of the territory, resulting in large areas of underexplored terrain in the south. The Kiyuk Lake property is located in the underexplored southwest corner of the Kivalliq Region of Nunavut within the Hearne domain of the ∼1.9 Ga western Churchill Province. The property is hosted by Proterozoic calc-silicate and clastic sedimentary units of the Hurwitz Group (<2.4–1.9 Ga) and the unconformably overlying Kiyuk Group (1.9–1.83 Ga). Gold mineralization in Proterozoic sedimentary rocks is rare in the Canadian Shield, so the Rusty Zone at Kiyuk Lake presents a unique opportunity to study the enigmatic gold mineralization hosted in such sedimentary rocks. Mineralization at the Rusty Zone is hosted by an immature lithic wacke cut by thin intermediate dikes that are associated with hydrothermal breccias composed of Fe-carbonate, calcite, calcic-amphibole, Fe-sulfide, Fe-oxide minerals, and gold. Textural and timing relationships suggest that the gold mineralization is post-sedimentary and syn- to post-intrusion of intermediate dikes. Stable isotope thermometry suggests that mineralization took place between 450 and 600 °C, and geochronological studies indicate that the intrusion and mineralization occurred before or about 1.83 Ga. Using basement breaching thrusts faults as conduits to the surface, over-pressurization along a later normal fault is thought to be the primary cause for the localized breccia pipe that controls gold mineralization. The hydrothermal fluids are postulated to be volatile-rich aqueous solutions exsolved from a source of cooling magmas at depth. Although sub-economic at present, the occurrence of high-grade gold in a Paleoproterozoic basin such as Kiyuk Lake could signal a new opportunity for exploration for gold in the Canadian Shield.

Chapter 10: Olympiada Gold Deposit, Yenisei Ridge, Russia

2020 ◽  
pp. 203-226
Author(s):  
A. M. Sazonov ◽  
K. V. Lobanov ◽  
E. A. Zvyagina ◽  
S. I. Leontiev ◽  
S. A. Silyanov ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Gold Mineralization ◽  
Sedimentary Rocks ◽  
Gold Deposits ◽  
Yenisei Ridge ◽  
Structural Factors ◽  
Tectonic Zone ◽  
Central Siberia ◽  
Western Margin ◽  
Clastic Sedimentary

Abstract The Olympiada deposit, containing >1,560 metric tons (t; 50 Moz) of gold at an average grade of 4 to 4.6 g/t Au, occurs in central Siberia, Russia. Over 30 years, the deposit produced more than 580 t of gold, including 200 t from oxidized ore grading 11.1 g/t. The deposit forms a 2-km-long, steeply dipping system, which is traced downdip for 1.7 km. It occurs in the Neoproterozoic orogen of the Yenisei Ridge at the western margin of the Siberian craton. This and other gold deposits in the district are controlled by the large, long-lived Tatarka-Ishimbino tectonic zone, marking a suture between terranes chiefly consisting of deformed Meso- to Neoproterozoic carbonate-clastic sedimentary rocks. The combination of lithologic and structural factors was critical for localization of gold mineralization associated with calcic and siliceous alteration accompanied by early arsenic and late antimony sulfides. As a result, very fine (10 μm) and high fineness (910–997) gold associates with diverse sulfides, especially arsenopyrite, and commonly contains mercury, similar to some characteristics of Carlin-type deposits. Geochronologic studies suggest that mineralization was formed during several stages between 817 and 660 Ma. The isotopic composition of Os and He, along with presence of anomalous Ni, Co, and Pt, points to a mantle mafic source, whereas isotopic composition of Pb and S suggest a contaminated crustal source, i.e., originating from a mix of mantle and crustal fluids.

Orthoquartzite pebbles in Archean conglomerate, North Spirit Lake, northwestern Ontario

1977 ◽  
Vol 14 (9) ◽  
pp. 1980-1990 ◽  
Author(s):  
J. A. Donaldson ◽  
Richard W. Ojakangas
Keyword(s):  
Greenstone Belt ◽  
Sedimentary Rocks ◽  
Canadian Shield ◽  
Superior Province ◽  
Lake Area ◽  
Definite Evidence ◽  
The North ◽  
Northwestern Ontario ◽  
Form Part ◽  
Quartz Grains

An Archean conglomerate in the North Spirit Lake area of northwestern Ontario contains rare orthoquartzite pebbles. Detailed study of these pebbles shows that mineralogically they are very mature, consisting of as much as 99.8 percent quartz and a heavy mineral suite of zircon, tourmaline, and apatite. Textures are typically bimodal, characterized by rounded sand-sized quartz grains set in a 'matrix-cement' of thoroughly recrystallized finer quartz grains. These orthoquartzite pebbles provide the first definite evidence for local tectonic stability of the Canadian Shield before deposition of the immature sedimentary rocks that form part of an Archean (>2.6 Ga) greenstone belt of the Superior Province.

Stratigraphy and lithogeochemistry of rocks from the Nugget Pond Deposit area, Baie Verte Peninsula, Newfoundland

2021 ◽  
Author(s):  
C Mueller ◽  
S J Piercey ◽  
M G Babechuk ◽  
D Copeland
Keyword(s):  
Gold Mineralization ◽  
Sedimentary Rocks ◽  
Mafic Rocks ◽  
Basaltic Rocks ◽  
Late Cambrian ◽  
Lower Unit ◽  
Iapetus Ocean ◽  
Post Archean Australian Shale ◽  
Clastic Sedimentary ◽  
Ocean Ridge

Stratigraphic and lithogeochemical data were collected from selected drill core from the Nugget Pond gold deposit in the Betts Cove area, Newfoundland. The stratigraphy consists of a lower unit of basaltic rocks that are massive to pillowed (Mount Misery Formation). This is overlain by sedimentary rocks of the Scrape Point Formation that consist of lower unit of turbiditic siltstone and hematitic cherts/iron formations (the Nugget Pond member); the unit locally has a volcaniclastic rich-unit at its base and grades upwards into finer grained volcaniclastic/turbiditic rocks. This is capped by basaltic rocks of the Scrape Point Formation that contain pillowed and massive mafic flows that are distinctively plagioclase porphyritic to glomeroporphyritic. The mafic rocks of the Mount Misery Formation have island arc tholeiitic affinities, whereas Scrape Point Formation mafic rocks have normal mid-ocean ridge (N-MORB) to backarc basin basalt (BABB) affinities. One sample of the latter formation has a calc-alkalic affinity. All of these geochemical features are consistent with results and conclusions from previous workers in the area. Clastic sedimentary rocks and Fe-rich sedimentary rocks of the Scrape Point Formation have features consistent with derivation from local, juvenile sources (i.e., intra-basinal mafic rocks). The Scrape Point Formation sedimentary rocks with the highest Fe/Al ratios, inferred to have greatest amount of hydrothermally derived Fe, have positive Ce anomalies on Post-Archean Australian Shale (PAAS)-normalized trace element plots. These features are consistent with having formed via hydrothermal venting into an anoxic/ sub-oxic water column. Further work is needed to test whether these redox features are a localized feature (i.e., restricted basin) or a widespread feature of the late Cambrian-early Ordovician Iapetus Ocean, as well as to delineate the role that these Fe-rich sedimentary rocks have played in the localization of gold mineralization within the Nugget Pond deposit.

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.

Chapter 15: Goldstrike Gold System, North Carlin Trend, Nevada, USA

2020 ◽  
pp. 313-334
Author(s):  
Paul J. Dobak ◽  
François Robert ◽  
Shaun L.L. Barker ◽  
Jeremy R. Vaughan ◽  
Douglas Eck
Keyword(s):  
Gold Mineralization ◽  
Normal Fault ◽  
Thermal Anomaly ◽  
Fault System ◽  
Normal Faults ◽  
Main Stage ◽  
Arsenian Pyrite ◽  
Carlin Trend ◽  
Structural Architecture ◽  
Clastic Sedimentary

Abstract The Eocene Goldstrike system on the Carlin Trend in Nevada is the largest known Carlin-type gold system, with an endowment of 58 million ounces (Moz) distributed among several coalesced deposits in a structural window of gently dipping carbonate rocks below the regional Roberts Mountains thrust. The 3.5- × 2.5-km Goldstrike system is bounded to the east by the Post normal fault system and to the south by the Jurassic Goldstrike diorite stock and is partly hosted in the favorable slope-facies apron of the Bootstrap reef margin that passes through the system. The carbonate and clastic sedimentary sequence is openly folded, cut by sets of reverse and normal faults, and intruded by the Jurassic Goldstrike stock and swarms of Jurassic and Eocene dikes, establishing the structural architecture that controlled fluid flow and distribution of Eocene mineralization. A proximal zone of permeability-enhancing decarbonatization with anomalous gold (>0.1 ppm) extends a few hundreds of meters beyond the ore footprint and lies within a carbonate δ18O depletion anomaly extending ~1.4 km farther outboard. The full extent of the larger hydrothermal system hosting Goldstrike and adjacent deposits on the northern Carlin Trend is outlined by a 20- × 40-km thermal anomaly defined by apatite fission-track analyses. The bulk of the mineralization is hosted in decarbonatized sedimentary units with elevated iron contents and abundant diagenetic pyrite relative to background. Gold is associated with elevated concentrations of As, Tl, Hg, and Sb, and occurs in micron-sized arsenian pyrite grains or in arsenian pyrite overgrowths on older, principally diagenetic pyrite, with sulfidation of available iron as the main gold precipitation mechanism. The intersection of a swarm of Jurassic lamprophyre dikes with the edge of the limestone reef provided a favorable deeply penetrating structural conduit within which a Jurassic stock acted as a structural buttress, whereas the reef’s slope-facies apron of carbonate units, with high available iron content, provided a fertile setting for Carlin-type mineralization. The onset of Eocene extension coupled with a southwestward-sweeping Cenozoic magmatic front acted as the trigger for main-stage gold mineralization at 40 to 39 Ma. All these factors contributed to the exceptional size and grade of Goldstrike.

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

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