Structural setting, textures, and timing of hydrothermal vein systems in the Val d'Or camp, Abitibi, Canada: implications for the evolution of transcrustal, second- and third-order fault zones and gold mineralization

2000 ◽  
Vol 37 (1) ◽  
pp. 95-114 ◽  
Author(s):  
P Neumayr ◽  
S G Hagemann ◽  
J -F Couture
Keyword(s):  
Quartz Vein ◽  
Gold Mineralization ◽  
Shear Zones ◽  
Fault Zones ◽  
Third Order ◽  
Tectonic Zone ◽  
Quartz Veins ◽  
Fluid Systems ◽  
Quartz Grains ◽  
Order Structures

In the Val d'Or camp, Archean Abitibi greenstone belt, Canada, numerous gold-mineralized second- and third-order fault zones are spatially associated with the transcrustal Cadillac Tectonic Zone (CTZ). This situation is used to test whether fluid systems in the CTZ have a similar structural timing to those in the gold-hosting structures, and hence the CTZ could represent the main fluid conduit in the camp. The transcrustal CTZ at Orenada No. 2 contains structurally complex vein systems, with mineralized quartz-tourmaline veins related to both D2 oblique-reverse faulting and F3 dextral asymmetric folding, both of which have been overprinted by unmineralized subhorizontal and subvertical quartz veins. Quartz ± tourmaline veins within second- and third-order shear zones at Paramaque and Rivière Héva also formed during D2 deformation and have been, at least at Rivière Héva, deformed by F3 asymmetric folding. In contrast, mineralized quartz vein systems at Cartier Malartic are controlled by F3 folding and overprinted by late-stage D3 faults which host late quartz-tourmaline veins. Quartz vein textures are consistent with these timing relations, because D2-controlled veins contain deformed quartz grains, whereas quartz in D3-controlled veins is unstrained. The D2 and D3 timing of mineralized quartz veins in the transcrustal CTZ and in second- and third-order structures is consistent with the notion that the CTZ represents the main fluid conduit and that mineralization occurred in linked second- and third-order structures. The different timing of quartz-tourmaline veins in different shear zones indicates that the veins were probably hydraulically linked to the CTZ during at least two different episodes. The location of Cartier Malartic structurally below the CTZ indicates that fluids travelled either downward from the main conduit or that the shear zone was part of the CTZ.

Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: the case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada

2007 ◽  
Vol 44 (6) ◽  
pp. 745-773 ◽  
Author(s):  
P Neumayr ◽  
S G Hagemann ◽  
D A Banks ◽  
B WD Yardley ◽  
J -F Couture ◽  
...  
Keyword(s):  
Hydrothermal Fluid ◽  
Gold Mineralization ◽  
Shear Zones ◽  
Wall Rock ◽  
Higher Order ◽  
Hydrothermal Fluids ◽  
Tectonic Zone ◽  
Quartz Veins ◽  
Hydrothermal Quartz ◽  
Lower Fluid

Detailed fluid geochemistry studies on hydrothermal quartz veins from the Rouyn-Noranda and Val-d'Or areas along the transcrustal Cadillac Tectonic Zone (CTZ) indicate that unmineralized (with respect to gold) sections of the CTZ contained a distinct CO2-dominated, H2S-poor hydrothermal fluid. In contrast, both gold mineralized sections of the CTZ (e.g., at Orenada #2) and associated higher order shear zones have a H2O–CO2 ± CH4–NaCl hydrothermal fluid. Their CO2/H2S ratios indicate H2S-rich compositions. The Br/Cl compositions in fluid inclusions trapped in these veins indicate that hydrothermal fluids have been equilibrated with the crust. Oxygen isotope ratios from hydrothermal quartz veins in the CTZ are consistently 2‰ more enriched than those of associated higher order shear zones, which are interpreted to be a function of greater fluid/rock ratios in the CTZ and lower fluid/rock ratios, and more efficient equilibration of the hydrothermal fluid with the wall rock, in higher order shear zones. An implication from this study is that the lower metal endowment of the transcrustal CTZ, when compared with the higher metal endowment in higher order shear zones (ratio of about 1 : 1000), may be the result of the lack of significant amounts of H2O–H2S rich fluids in most of the CTZ. In contrast, gold mineralization in the higher order shear zones appear to be controlled by the high H2S activity of the aqueous fluids, because gold was likely transported in a bisulfide complex and was deposited during sulfidation reactions in the wall rock and phase separation in the quartz veins.

Regional setting of vein-style gold mineralization around the Goldlund mine, Sandybeach Lake area, northwestern Ontario

1990 ◽  
Vol 27 (12) ◽  
pp. 1590-1608 ◽  
Author(s):  
Lesley Chorlton
Keyword(s):  
Gold Mineralization ◽  
Shear Zones ◽  
Main Body ◽  
Lake Area ◽  
Lateral Shear ◽  
Quartz Veins ◽  
Northwestern Ontario ◽  
Stage 4 ◽  
Shear Sense ◽  
Stage 1

The Sandybeach Lake area was deformed in four stages. Stage 1 produced gently south-southeast-dipping foliations at low angles to bedding. Stage 2 involved draping of these planes and formation of contact-strain aureoles related to the emplacement of granitoid stocks. Stage 3 produced doubly plunging folds, steep foliations, and shear zones, which resulted from regional transpression, with a sinistral lateral shear sense along this arm of the Wabigoon greenstone belt. Stage 4 produced minor folds and shear displacements in some places and final tightening of stage 3 folds in others, compatible with final regional convergence.Regional quartz veins, including those carrying gold, appear to have filled tensional fractures related to bulk belt-perpendicular shortening and belt-parallel extension, sinistral shear, and tightening of folds in sheetlike competent bodies. Veins and mineralization thus coincided with late stage 3 deformation, possibly overlapping stage 4.Auriferous vein occurrences at the Goldlund mine display geometries similar to those of veins in the surrounding region. The main body of auriferous vein mineralization is hosted by a thick, composite metatonalite–metadiorite sheet. The vein system of this zone likely originated during the steepening and axial-plane transposition of the southeast-dipping limb near the southwest-plunging end of a stage 3 fold.

scholarly journals Carbonic fluids in the Hamadi gold deposit, Sudan: origin and contribution to gold mineralization

2017 ◽  
Vol 54 (5) ◽  
pp. 494-511 ◽  
Author(s):  
Xi-hui Cheng ◽  
Jiu-hua Xu ◽  
Jian-xiong Wang ◽  
Qing-po Xue ◽  
Hui Zhang
Keyword(s):  
Gold Deposit ◽  
Melting Temperature ◽  
Fluid Inclusions ◽  
Gold Mineralization ◽  
Narrow Range ◽  
Shear Zones ◽  
Quartz Veins ◽  
Wide Range ◽  
Homogenization Temperatures ◽  
Gold Bearing

The Hamadi gold deposit is located in North Sudan, and occurs in the Neoproterozoic metamorphic strata of the Arabian–Nubian Shield. Two types of gold mineralization can be discerned: gold-bearing quartz veins and altered rock ores near ductile shear zones. The gold-bearing quartz veins are composed of white to gray quartz associated with small amounts of pyrite and other polymetallic sulfide minerals. Wall-rock alterations include mainly beresitization, epidotization, chloritization, and carbonatization. CO2-rich inclusions are commonly seen in gold-bearing quartz veins and quartz veinlets from gold-bearing altered rocks; these include mainly one-phase carbonic (CO2 ± CH4 ± N2) inclusions and CO2–H2O inclusions with CO2/H2O volumetric ratios of 30% to ∼80%. Laser Raman analysis does not show the H2O peak in carbonic inclusions. In quartz veins, the melting temperature of solid CO2 (Tm,CO2) of carbonic inclusions has a narrow range of −59.6 to −56.8 °C. Carbonic inclusions also have CO2 partial homogenization temperatures (Th,CO2) of −28.3 to +23.7 °C, with most of the values clustering between +4.0 and +20 °C; all of these inclusions are homogenized into the liquid CO2 state. The densities range from 0.73 to 1.03 g/cm3. XCH4 of carbonic fluid inclusions ranges from 0.004 to 0.14, with most XCH4 around 0.05. In CO2–H2O fluid inclusions, Tm,CO2 values are recorded mostly at around −57.5 °C. The melting temperature of clathrate is 3.8–8.9 °C. It is suggested that the lowest trapping pressures of CO2 fluids would be 100 to ∼400 MPa, on the basis of the Th,CO2 of CO2-bearing one-phase (LCO2) inclusions and the total homogenization temperatures (Th,tot) of paragenetic CO2-bearing two-phase (LCO2–LH2O) inclusions. For altered rocks, the Tm,CO2 of the carbonic inclusions has a narrow range of −58.4 to ∼−57.0 °C, whereas the Th,CO2 varies widely (−19 to ∼+29 °C). Most carbonic inclusions and the carbonic phases in the CO2–H2O inclusions are homogenized to liquid CO2 phases, which correspond to densities of 0.70 to ∼1.00 g/cm3. Fluid inclusions in a single fluid inclusion assemblage (FIA) have narrow Tm,CO2 and Th,CO2 values, but they vary widely in different FIAs and non-FIAs, which indicates that there was a wide range of trapping pressure and temperature (P–T) conditions during the ore-forming process in late retrograde metamorphism after the metamorphism peak period. The carbonic inclusions in the Hamadi gold deposit are interpreted to have resulted from unmixing of an originally homogeneous aqueous–carbonic mixture during retrogress metamorphism caused by decreasing P–T conditions. CO2 contributed to gold mineralization by buffering the pH range and increasing the gold concentration in the fluids.

scholarly journals Les Altérations Hydrothermales Associées À La Minéralisation Aurifère Du Gisement De Dougbafla (District d’Oumé-Hiré, Centre-Ouest De La Côte d’Ivoire)

2017 ◽  
Vol 13 (30) ◽  
pp. 108
Author(s):  
Ouattara Aboubakar Sidik ◽  
Coulibaly Yacouba ◽  
Kouadio Fossou J-L. H.
Keyword(s):  
Cote D'ivoire ◽  
Quartz Vein ◽  
Côte D’Ivoire ◽  
Gold Mineralization ◽  
West African ◽  
Cote D’Ivoire ◽  
West African Craton ◽  
Quartz Veins ◽  
Côte D'ivoire ◽  
The One

The Dougbafla gold deposit is located in the West-Central part of Côte d’Ivoire at about 240 km from Abidjan, on the Birimian greenstone belt of Fettèkro (West African craton). The lithologies of this deposit can be divided into three lithotectonic units which correspond to volcanic, sedimentary, and plutonic assemblages metamorphosed in the shale facies. Hydrothermalism, on the one hand, caused a pervasive alteration of the primary paragenesis marked by sericitic, silica, and carbonate alteration. On the other hand, it causes a vein alteration materialized by quartz veins. These hydrothermal alterations induced two types of gold mineralization in the Dougbafla deposit. These are: (i) disseminated gold and sulphide mineralization in the granophyre associated with sericite, silica and dolomite alteration in which no quartz vein has been reported; this type however is controlled by the intrusion of granophyre and (ii) a quartz vein mineralization controlled by deformation.

scholarly journals The geological and structural controls of gold mineralization in Qala en Nahal-Um Sagata region, South Gedarif, Sudan

2020 ◽  
Vol 59 (3) ◽  
pp. 19-26
Author(s):  
Musab Awad Ahmed HASSAN ◽  
◽  
Aleksandr Evgen’yevich KOTEL’NIKOV ◽  
Keyword(s):  
Gold Mineralization ◽  
Mineral Exploration ◽  
Structural Evolution ◽  
Absorption Spectrometry ◽  
Shear Zones ◽  
Structural Features ◽  
Geological Structure ◽  
Geological Mapping ◽  
Quartz Veins ◽  
Ophiolitic Complex

Relevance and purpose of the work. The study area is located in Gedarif state in Sudan. The ongoing work is aimed at solving fundamental problems of the geological structure of the Qala En Nahal-Um Saqata Ophiolitic Complex and applied tasks of mineral exploration. Detailed studies are being conducted for the first time in this area. The purpose of the investigation is to study the geological and structural features of the region, as well as to obtain information about the localization of gold mineralization. Methods of research. Within the study area, a geological mapping of the ophiolitic complex was carried out. It’s included an analysis of structural elements for investigation of the structural evolution and the phases of deformation. Chemical analysis of the mineralized quartz veins to determine the gold was carried out by Atomic Absorption Spectrometry (AAS) technique at the ALS Laboratory in Saudi Arabia. Results of the work. The investigation of the structural evolution revealed at least three phases of deformation. The gold mineralization occurs in auriferous quartz veins, which are hosted in metavocano-sedimentary, sheared synorogenic granites and listvenites. The auriferous quartz veins are structurally controlled by dominantly NE main shear directions. Conclusions. The gold mineralization in the area can be classified shear zone related mineralization, which is formed during the final event accomplished by crustal cooling, and formation of auriferous quartz vein along shear zones. Gold concentration were recorded in both quartz veins and associates alteration rocks. The area is promising for the presence of a gold deposit.

Structure of veins in a gold–pyrite deposit in banded iron formation, Amalia greenstone belt, South Africa

1986 ◽  
Vol 123 (6) ◽  
pp. 601-609 ◽  
Author(s):  
J. R. Vearncombe
Keyword(s):  
Greenstone Belt ◽  
Quartz Vein ◽  
Gold Mineralization ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Vein Wall ◽  
Quartz Veins ◽  
Anticlockwise Rotation ◽  
Fibre Growth ◽  
Mineralizing Fluids

AbstractFibrous quartz veins in deformed banded iron formation of the Amalia greenstone belt, southwestern Transvaal, are spatially related to gold–pyrite mineralization in both wallrock and vein inclusions. Poles to quartz vein orientations show a general parallelism with mineral elongation and fold plunges of the principal deformation in the wallrock. Quartz vein fibres show a consistent anticlockwise rotation, late components being subparallel to the elongation lineation, suggesting veining was probably synchronous with the principal deformation. Antitaxial fibrous veins, which dominate the mineralized banded iron formation, formed by the process of crack–seal which channelled mineralizing fluids along the vein walls, increasing the potential for fluid–wallrock interaction. Gold mineralization in quartz veins occurs in wall-parallel slivers of banded iron formation which have been plucked off the vein wall during antitaxial fibre growth. Mineralization can be explained by a process of fluid–wallrock interaction with sulphidation and gold precipitation.

The Saidu Gold Deposit of Southern Altai, China: Mineralizing Stages and Ore-Forming Fluids Evolution

2013 ◽  
Vol 734-737 ◽  
pp. 215-218
Author(s):  
Guo Rui Zhang ◽  
Jiu Hua Xu ◽  
Li Hua Shan ◽  
Hui Zhang ◽  
Xiao Feng Wei
Keyword(s):  
Gold Deposit ◽  
Gold Mineralization ◽  
Early Stage ◽  
Shear Zones ◽  
Ductile Shear Zone ◽  
Tectonic Zone ◽  
Low Salinity ◽  
Ore Bodies ◽  
Evolution Characteristics ◽  
Homogenization Temperatures

The Saidu gold deposit is located in the northwest part of Ertix Tectonic Zone in Xinjiang. The ore bodies occur in altered mylonite zones within the Mar-kakol giant fault zone and are controlled by the ductile shear zone. The structural-metallogenic fluids of the early stage are characterized by mesothermal-hydrothermal CO2-N2-rich fluids, with homogenization temperatures of fluid inclusions being 252~408°C. The tectonic-metallogenic fluids at the middle stage are characterized by CO2-H2O fluids, with homogenization temperatures being 203~326°C. The fluids at the late stage were epithermal-mesothermal low salinity aqueous solutions, with homogenization temperatures being 120~221°C. The main gold mineralization was related to the post-orogenic extension environment, with the evolution characteristics corresponding to the evolution of shear zones.

Structural controls on hypozonal orogenic gold mineralization in the La Ronge Domain, Trans-Hudson Orogen, Saskatchewan

2004 ◽  
Vol 41 (12) ◽  
pp. 1453-1471
Author(s):  
Bruno Lafrance ◽  
Larry M Heaman
Keyword(s):  
Gold Mineralization ◽  
Shear Zones ◽  
Oceanic Lithosphere ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Lake Area ◽  
Structural Controls ◽  
Quartz Veins ◽  
Metavolcanic Rocks ◽  
Orogenic Gold Mineralization

The La Ronge Domain is a granite–greenstone belt in the Saskatchewan segment of the ca. 1.9–1.8 Ga Trans-Hudson Orogen. The La Ronge volcanic arc was accreted to the Archean Hearne craton from ca. 1.87 to 1.86 Ga. Subduction of oceanic lithosphere beneath the accreted La Ronge – Hearne margin produced a voluminous suite of continental-arc intrusions. In the Waddy Lake area, the 1852.6 ± 1.5 Ma Corner Lake stock and 1859 ± 4 Ma and 1861 ± 2 Ma feldspar porphyry dykes crystallized from magmas generated from melting of the subducted oceanic slab. During the ca. 1.83–1.80 Trans-Hudson collision of the Hearne craton with the Archean Sask and Superior cratons, a penetrative regional foliation and a steeply plunging lineation formed within the La Ronge Domain. During further contraction across the domain, the deformation became localized in dextral and oblique-slip shear zones that generally follow contacts between more competent and less competent rock units. Orogenic gold mineralization is associated with quartz veins that are surrounded by hypozonal potassic and sulfidic alteration zones. The Komis gold deposit, the only past-producing gold mine in the Waddy Lake area, formed in the strain shadow of the Round Lake stock during the development of the regional foliation and lineation. Mineralization is associated with quartz veins that cut through tonalite dykes that behaved more brittlely than the surrounding metavolcanic rocks. The Golden Heart and Corner Lake gold deposits are hosted by south-side-up oblique-slip shear zones, which belong to a regional system of structures that extend from Saskatchewan to Manitoba.

scholarly journals Mapping Main Structures and Related Mineralization of the Arabian Shield (Saudi Arabia) Using Sharp Edge Detector of Transformed Gravity Data

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 71
Author(s):  
Ahmed M. Eldosouky ◽  
Reda A. Y. El-Qassas ◽  
Luan Thanh Pham ◽  
Kamal Abdelrahman ◽  
Mansour S. Alhumimidi ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Gold Mineralization ◽  
Gravity Data ◽  
Shear Zones ◽  
Fault Zones ◽  
Gold Deposits ◽  
Fault System ◽  
Arabian Shield ◽  
Potential Field Data ◽  
Najd Fault System

Saudi Arabia covers most of the Arabian Peninsula and is characterized by tectonic regimes ranging from Precambrian to Recent. Using gravity data to produce the lateral boundaries of subsurface density bodies, and edge detection of potential field data, a new subsurface structural map was created to decipher the structural framework controls on the distribution of gold deposits in Saudi Arabia. Moreover, we detected the relationships between major structures and mineral accumulations, thereby simultaneously solving the problem of edge detectors over complex tectonic patterns for both deeper and shallower origins. Analytic signal (ASg), theta map (TM), TDX, and softsign function (SF) filters were applied to gravity data of Saudi Arabia. The results unveil low connectivity along the Najd fault system (NFS) with depth, except perhaps for the central zones along each segment. The central zones are the location of significant gold mineralization, i.e., Fawarah, Gariat Avala, Hamdah, and Ghadarah. Moreover, major fault zones parallel to the Red Sea extend northward from the south, and their connectivity increases with depth and controls numerous gold mines, i.e., Jadmah, Wadi Bidah, Mamilah, and Wadi Leif. These fault zones intersect the NFS in the Midyan Terrane at the northern part of the AS, and their conjugation is suggested to be favorable for gold mineralization. The SF maps revealed the boundary between the Arabian Shield and Arabian Shelf, which comprises major shear zones, implying that most known mineralization sites are linked to post-accretionary structures and are not limited to the Najd fault system (NFS).

Sign in / Sign up

Export Citation Format

Share Document