scholarly journals Geochronological and Geochemical Constraints on the Formation of the Giant Zaozigou Au-Sb Deposit, West Qinling, China

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 37 ◽  
Author(s):  
Hao-Cheng Yu ◽  
Chang-An Guo ◽  
Kun-Feng Qiu ◽  
Duncan McIntire ◽  
Gui-Peng Jiang ◽  
...  
Keyword(s):  
Mineral Assemblage ◽  
Spatial Association ◽  
Massive Sulfide ◽  
Stage Model ◽  
Sulfide Mineralization ◽  
Low Oxygen ◽  
Ore Formation ◽  
West Qinling ◽  
T Values ◽  
Geochemical Constraints

The Zaozigou Au-Sb deposit has been controversial in its genesis and remains one of the most difficult ore systems to fully understand in West Qinling. The mineralization shows a broad spatial association with Triassic dikes and sills, which were previously thought to be genetically related to mineralization. Our U-Pb zircon dating in this contribution indicates that the ore-hosting porphyritic dacites were formed at 246.1 ± 5.2 Ma and 248.1 ± 3.8 Ma. The magmatic zircons yield εHf(t) values ranging from −12.5 to −8.9, with corresponding two-stage model ages of 2.08 to 1.83 Ga. The magma therefore could be derived from partial melting of Paleoproterozoic crustal materials. The ore-hosting porphyritic dacites have low oxygen fugacity, with ΔFMQ ranging from −4.61 to −2.56, indicating that magmas could have been sulfide-saturated during evolution in deep chambers and precluding the possibility that metals were released from the melt. Zaozigou exhibits characteristics widespread volcanics, massive sulfide mineralization, rare reduced mineral assemblage and discrete alteration zones which are not typical of reduced intrusion-related or porphyry gold systems. We propose that the spatially-related Triassic porphyritic dacite and dike swarm is not genetically related to the ore formation of Zaozigou Au-Sb deposit.

Mise‐a‐la‐masse survey for an auriferous sulfide deposit

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 70-77 ◽  
Author(s):  
B. B. Bhattacharya ◽  
Dinesh Gupta ◽  
Buddhadeb Banerjee ◽  
Shalivahan
Keyword(s):  
Massive Sulfide ◽  
Sulfide Deposit ◽  
Sulfide Mineralization ◽  
Gold Exploration ◽  
Copper Mineralization ◽  
Geophysical Surveys ◽  
Sulfide Content ◽  
Equipotential Map ◽  
Massive Sulfide Mineralization ◽  
Gold Bearing

A mise‐a‐la‐masse survey was carried out in Bhukia area, Banswara district, Rajasthan, India for auriferous sulfide occurrences. This area was originally surveyed for copper mineralization. Exploratory drilling, however, proved it to be economically not viable. The area was reopened for geophysical surveys when grab samples indicated the presence of gold. Initial geophysical surveys for copper mineralization showed electromagnetic, induced polarization, and resistivity anomalies. At first, one borehole was drilled for gold exploration on the basis of initial geophysical surveys. It encountered massive sulfide mineralization in association with gold. Borehole logging and a mise‐a‐la‐masse survey were carried out in this borehole. Three further boreholes drilled on the basis of the mise‐a‐la‐masse results encountered massive sulfide mineralization in association with gold. One of the three boreholes, 100 m from the first borehole along strike, was used for another set of mise‐a‐la‐masse measurements. A composite equipotential map was prepared using the results of mise‐a‐la‐masse results of both the boreholes. The equipotential contours show a north‐northwest‐south‐southeast trend of mineralization. The boreholes drilled on the basis of the mise‐a‐la‐masse results have delineated a strike length of more than 500 m of gold‐bearing sulfide mineralization. The sulfide content ranges from 10 to 40% and gold concentration ranges from 2 to 6 ppm. The dip and plunge of the lode, as anticipated from the mise‐a‐la‐masse results, are toward the west and north, respectively. Mise‐a‐la‐masse surveys are continuing in the adjoining areas.

Ni-Cu sulfide mineralization and PGM from the Samapleu mafic-ultramafic intrusion, Yacouba complex, western Ivory Coast

2021 ◽  
Vol 59 (4) ◽  
pp. 631-665
Author(s):  
Franck Gouedji ◽  
Christian Picard ◽  
Marc Antoine Audet ◽  
Thierry Augé ◽  
Jorge Spangenberg
Keyword(s):  
Ivory Coast ◽  
Massive Sulfide ◽  
Sulfide Mineralization ◽  
Platinum Group Minerals ◽  
Thermo Fisher Scientific ◽  
Mass Spectrometer System ◽  
Ultramafic Intrusion ◽  
Platinum Group ◽  
Mineralizing Process ◽  
Spectrometer System

ABSTRACT The mafic-ultramafic Samapleu deposits of the Yacouba complex, which host nickel, copper sulfides, and platinum-group minerals, are located in the Biankouma-Silipou region, western Ivory Coast. These intrusions originate from the mantle and would have been established during the Proterozoic (2.09 Ga) around 22 km deep within the Archean granulites (3.6–2.7 Ga) which at least partially contaminated them. Platinum-group and sulfide minerals from the Samapleu deposits were studied using optical microscopy, scanning electron microscopy, the electronic microprobe, X-ray fluorescence, fire assay, and a Thermo Fisher Scientific Delta S isotope ratio mass spectrometer system. The sulfide mineralization (mainly pyrrhotite, pentlandite, chalcopyrite ± pyrite) is mainly disseminated with, in places, semi-massive to massive sulfide veins. It is especially abundant in pyroxenite horizons with net or breccia textures. The isotopic ratios of sulfur measured from the sulfides (an average of 0.1‰), the R factor (between 1500 and 10,000), and the Cu/Pd ratios indicate a mantle source. Thus, the sulfides would have formed from sulfide liquids produced by immiscibility from the silicate mantle magma under mafic-ultramafic intrusion emplacement conditions and with possible geochemical modification of the magmas by assimilation of the surrounding continental crust. The platinum-group minerals (michenerite, merenskyite, moncheite, Co-rich gersdorffite, irarsite, and hollingworthite) are mainly associated with the sulfide phases. The nature of the platinum-group minerals is indicative of the probable role of late-magmatic hydrothermal fluids during the mineralizing process.

An Overview of the ULU Gold Deposit, High Lake Volcanic Belt, Nunavut, Canada

2004 ◽  
Vol 13 (1-4) ◽  
pp. 15-23
Author(s):  
E. FLOOD ◽  
P. KLEESPIES ◽  
M. TANSEY ◽  
H. MUNTANION ◽  
R. CARPENTER
Keyword(s):  
Mineral Assemblage ◽  
Spatial Association ◽  
Sedimentary Rocks ◽  
Volcanic Belt ◽  
Wall Rock ◽  
Potassium Feldspar ◽  
Lode Gold ◽  
The Core ◽  
Flood Zone ◽  
Alteration Minerals

Abstract BHP Minerals discovered the Archean lode gold ULU deposit on the western margin of the High Lake Volcanic Belt in 1989. The greenschist to amphibolite facies mafic volcanic and sedimentary rocks on the property are folded into a 5 km-long anticline. There is a close spatial association of Au-As zones to the trace of this F2 ULU anticline. The largest of these auriferous zones, the Flood zone, is localized at the core of the fold. The southeast-trending Flood zone consists of several anastomosing lenses that have been traced for 435 m on surface. Overall, it dips steeply (70° to 80°) to the southwest and has been intersected to depths below 600 m. The hosting high-iron tholeitic basalt displays a lower amphibolite mineral assemblage of ferrohornblende + plagioclase + ilmenite with accessory quartz and epidote. Alteration minerals include biotite, chlorite, hornblende, actinolite-tremolite, and potassium feldspar (microcline) with minor calcite, epidote, tourmaline, and titanite. The highest gold values occur where brecciated basaltic wall-rock clasts are replaced by acicular arsenopyrite + quartz + K-feldspar. BHP Minerals completed 54,783 m of both exploration and resource development drilling before selling the ULU property to Echo Bay Mines in 1995. Development of ULU as a satellite deposit to Echo Bay’s Lupin mine began in 1996. A -15% ramp was extended to the 155-meter level, and 16,011 m of underground drilling were completed before the decline in gold prices forced a suspension of activities at ULU in August 1997. The current owners, Wolfden Resources Inc., drilled 18,569 m in 2004 to increase confidence in the resource blocks. Following this drill program, a revised resource calculated by an independent consultant determined that the ULU deposit contains an inferred/indicated mineral resource of 1,130,000 t grading 11.34 g/t gold (373,748 oz) to the 360-m level. The portal was re-opened in 2005 and a prefeasibility study is underway.

The Role of Factor and Regression Analysis in the Interpretation of Geochemical Reconnaissance Data

1975 ◽  
Vol 12 (8) ◽  
pp. 1316-1330 ◽  
Author(s):  
L. G. Closs ◽  
Ian Nichol
Keyword(s):  
Factor Analysis ◽  
Regression Analysis ◽  
Massive Sulfide ◽  
Glacial Till ◽  
Geochemical Data ◽  
Sulfide Mineralization ◽  
Element Data ◽  
Copper And Zinc ◽  
The Individual

The interpretation of exploration oriented geochemical data frequently requires the recognition of subtle features related to mineralization, from the more obvious geochemical expressions of bedrock and surface environments. A number of previous investigations have indicated the potential of various computerized interpretational procedures as aids in identifying these features in geochemical data. The present investigation was concerned with the interpretation of multi-element data from a 750 mile2 {1942.5 km2) area of the Notre Dame Bay district of Newfoundland. The area is underlain by a series of Ordovician and Silurian sediments and volcanics and intrusives overlain by glacial deposits mostly composed of glacial till. Massive sulfide mineralization including the Whalesback and Gullbridge deposits occur within the Ordovician volcanics. R mode factor analysis was employed to establish the character and distribution of the principle metal associations related to bedrock and surface environment contributing to the overall data distribution. The factor scores were regressed against the individual metal concentrations of the elements composing the respective factors, the resulting residuals of the metals reflecting the component of metal related to some sources other than those reflected by the metal associations established by factor analysis. Anomalous areas of residual copper and zinc distributions indicate the areas of known sulfide mineralization more closely than the untreated metal distributions. On this basis, anomalous areas of residual copper and zinc, unrelated to known sulfide mineralization warrant further exploration investigation. It is therefore concluded that a combination of factor and regression analysis on multi-element data from the Notre Dame Bay district of Newfoundland serves to highlight subtle though significant features in multi-element data possibly related to mineralization that were not apparent from a consideration of the untreated data.

scholarly journals U-Th-He Geochronology of Pyrite from the Uzelga VMS Deposit (South Urals)—New Perspectives for Direct Dating of the Ore-Forming Processes

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 629
Author(s):  
Olga Yakubovich ◽  
Mary Podolskaya ◽  
Ilya Vikentyev ◽  
Elena Fokina ◽  
Alexander Kotov
Keyword(s):  
Methodological Approach ◽  
Massive Sulfide ◽  
Ore Deposits ◽  
South Urals ◽  
Volcanogenic Massive Sulfide ◽  
Ore Formation ◽  
Relative Simplicity ◽  
Facies Metamorphism ◽  
Thermal Extraction ◽  
Pyrite Sample

We report on the application of the U-Th-He method for the direct dating of pyrite and provide an original methodological approach for measurement of U, Th and He in single grains without loss of parent nuclides during thermal extraction of He. The U-Th-He age of ten samples of high-crystalline stoichiometric pyrite from unoxidized massive ores of the Uzelga volcanogenic massive sulfide (VMS) deposit, South Urals, is 382 ± 12 Ma (2σ) (U concentrations ~1–5 ppm; 4He ~10−4 cm3 STP g−1). This age is consistent with independent (biostratigraphic) estimations of the age of ore formation (ca, 389–380 Ma) and is remarkably older than the probable age of the regional prehnite-pumpellyite facies metamorphism (~340–345 Ma). Our results indicate that the U-Th-He dating of ~1 mg weight pyrite sample is possible and open new perspectives for the dating of ore deposits. The relative simplicity of U-Th-He dating in comparison with other geochronological methods makes this approach interesting for further application.

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