Massive sulfide deposits of the Noranda area, Quebec. V. The Corbet mine

1993 ◽  
Vol 30 (9) ◽  
pp. 1934-1954 ◽  
Author(s):  
T. J. Barrett ◽  
W. H. MacLean ◽  
S. Cattalani ◽  
L. Hoy
Keyword(s):  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Mass Change ◽  
Northwestern Part ◽  
Sulfide Deposits ◽  
Oxygen Isotope Ratios ◽  
Ore Body ◽  
Volcanic Formation ◽  
Calculated Mass ◽  
Volcanic Series

The Corbet deposit is located in the upper part of the Flavrian andesite, the lowest volcanic formation within cycle III of the Noranda Central Mine Sequence. The deposit consisted of one main lens of massive sulfides, and several smaller lenses, and contained 2.7 × 106 t of mineable ore at 2.92% Cu, 1.98% Zn, 20.6 g/t Ag, and 1.0 g/t Au. The orebody had a massive pyrrhotite–chalcopyrite core, which passed laterally into massive pyrite–sphalerite. The northwestern part of the ore-body is overlain by 50–100 m of Flavrian andesite, whereas the southeastern portion is overlain by Northwest rhyolite.Lavas within the Flavrian andesite and the lower Northwest rhyolite are low in K2O (<0.5%), and are partly of tholeiitic affinity, and partly of transitional affinity. The tholeiitic volcanic series has Zr/Y ratios of 2.8 to 4.5, whereas the transitional series has Zr/Y ratios of 4.5 to 7.1. The two series are also distinct in plots of Nb–Zr, Yb–Zr, Nb–Y, and the rare earth elements. These data indicate that two slightly different magma types existed in the chamber that fed this portion of the extrusive Central Mine Sequence.Alteration is most intense in the breccias of the upper Flavrian andesite, within ~50 m of the orebody, and is almost entirely chloritic. There is no zone of silicification, although moderate sericitization occurs lateral to and above the orebody. Mass-change calculations indicate that large amounts of SiO2 and CaO + Na2O were leached from the rocks by hydrothermal solutions, whereas large amounts of hydrothermal FeO and seawater MgO were added.Oxygen isotope depletions are among the largest in the Noranda area and extend laterally and vertically up to 300 m from the orebody. Within this volume, δ18O values of altered volcanic rocks have been decreased to values as low as 2 to −2‰. These depletions result from reactions with seawater at ~ 250–300 °C and from strong silica leaching, as indicated by mass-change calculations. The hydrothermal system at Corbet can be assessed using two lithogeochemical tools: calculated mass changes and oxygen isotope ratios, both of which are sensitive to water–rock ratio and temperature.

Massive sulfide deposits of the Noranda area, Quebec. IV. The Mobrun mine

1992 ◽  
Vol 29 (7) ◽  
pp. 1349-1374 ◽  
Author(s):  
T. J. Barrett ◽  
S. Cattalani ◽  
L. Hoy ◽  
J. Riopel ◽  
P.-J. Lafleur
Keyword(s):  
Hanging Wall ◽  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Calc Alkaline ◽  
Sulfide Deposits ◽  
Calculated Mass ◽  
Higher Temperature ◽  
Felsic Volcanic ◽  
Clear Change

The Mobrun polymetallic deposit near Rouyn–Noranda comprises two complexes of massive sulfide lenses within mainly felsic volcanic rocks of the Archean Blake River Group. The Main lens contained 3.37 Mt of massive sulfides, with 1989 reserves of 0.95 Mt at 0.81% Cu, 2.44% Zn, 30.3 g/t Ag, and 2.2 g/t Au. The 1100 complex, located ~250 m to the southeast of the Main complex, contains estimated 1989 reserves of 10.4 Mt at 0.76% Cu, 5.43% Zn, 37.4 g/t Ag, and 1.35 g/t Au.Host volcanic rocks of the Main complex are mostly massive, brecciated, and tuffaceous rhyolites. The rhyolites are commonly strongly sheared parallel to lithological contacts, which are locally displaced by high-angle faults. Immobile-element plots such as Y–Zr and Nb–Zr show a separation of rhyolite data into two distinct alteration trends that generally correspond to massive and in situ brecciated rhyolite of the footwall, and tuffaceous rhyolite of the hanging wall. The hanging wall has tholeiitic Zr/Y ratios (3–5), whereas the footwall has mildly calc-alkaline Zr/Y ratios (7–9). Several immobile-element trends indicate that there was a subtle but clear change in rhyolite composition near the time of ore deposition. Identification of chemically distinct footwall and hanging wall rhyolites allows these units to be recognized and traced along strike, even where alteration is strong. Sericitization and silicification extend at least 100 m from the orebody, with local chloritic zones in the upper footwall. Calculated mass changes indicate that the footwall generally has lost silica mass relative to the hanging wall. Alteration zones associated with mineralization have mass gains in FeO + MgO and K2O gains, but mass loss in silica.The 1100 complex, located stratigraphically below the Main complex, is hosted by rhyolite, with one main andesite interval in the footwall. The footwall contains three chemically distinct rhyolite types, all tholeiitic. Hanging-wall rhyolites are, however, mildly calc-alkaline, and thus are chemically comparable to, and correlated with, the footwall of the Main complex. Rhyolites within ~100 m stratigraphically of the Main and 1100 complexes commonly have positively shifted δ18O whole-rock values of 11–13‰. These high values are interpreted as the result of an initial, widespread phase of low-temperature hydrothermal alteration that increased δ18O values by 3–5‰ relative to unaltered rhyolites. Some footwall rhyolites, however, are relatively depleted in 18O, strongly depleted in Ca–Na and depleted in Eu2+. Rhyolites with these chemical features have been overprinted by higher temperature alteration, presumably in localized feeder zones. All four rhyolite types near the 1100 complex are chemically recognizable despite contrasting alteration.The orebodies are interpreted as synvolcanic, based on their occurrence along distinctive volcanic contacts, and the presence of primary sulfide textures where deformation is minor. The chemostratigraphic framework defined for the host rhyolite sequence can be used to trace critical volcanic contacts through lithologically monotonous, strongly altered, and faulted stratigraphy.

Oxygen isotope evolution of volcanic rocks at the Sturgeon Lake volcanic complex, Ontario

2000 ◽  
Vol 37 (1) ◽  
pp. 39-50 ◽  
Author(s):  
E M King ◽  
J W Valley ◽  
D W Davis
Keyword(s):  
Oxygen Isotope ◽  
Volcanic Rocks ◽  
Isotope Ratios ◽  
Hydrothermal Systems ◽  
Superior Province ◽  
Volcanic Complex ◽  
Volcanic Stratigraphy ◽  
Oxygen Isotope Ratios ◽  
Ore Body ◽  
The Many

Igneous zircons from the Sturgeon Lake volcanic complex, host to several massive sulphide deposits in the Superior Province, Canada, have an average δ18O(zircon) of 5.4 ± 0.3‰ VSMOW (n = 9 rocks). These zircons are from units differing in age by 18 million years in the 2.7 Ga complex. There is no detectable interaction of high δ18O, supracrustal lithologies in the magma. Quartz from volcanic units beneath the largest ore body, the Mattabi deposit, has an average δ18O of 9.3 ± 0.6‰. Quartz phenocrysts from the Mattabi unit and overlying volcanics have elevated and heterogeneous δ18O values averaging 13.8 ± 0.9‰ and are not in magmatic equilibrium with zircons. The δ18O values of whole-rock powders range from 5.6‰ to 14.3‰ and follow the trend observed in the δ18O values of quartz. Healed microcracks are visible in cathodoluminescence images (but are not obvious optically) of quartz phenocrysts from units with high δ18O values and disequilibrium Δ(quartz-zircon) suggesting that recrystallization facilitates the elevation of δ18O. Quartz phenocrysts from volcanic units with Δ(quartz-zircon) values near equilibrium at magmatic temperatures do not display healed microcracks in cathodoluminescence. The elevated δ18O(quartz) values are not restricted to units hosting orebodies, but are seen in all rocks in the volcanic stratigraphy that postdate eruption of the Mattabi unit. Oxygen isotope ratios combined with physical volcanology studies suggest that impermeable volcanic layers control the size and location of the many hydrothermal systems that may have occurred in the Sturgeon Lake complex.

Massive sulfide deposits of the Noranda area, Quebec. III. The Ansil mine

1991 ◽  
Vol 28 (11) ◽  
pp. 1699-1730 ◽  
Author(s):  
T. J. Barrett ◽  
W. H. MacLean ◽  
S. Cattalani ◽  
L. Hoy ◽  
G. Riverin
Keyword(s):  
Hanging Wall ◽  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Hydrothermal Activity ◽  
Sulfide Deposit ◽  
Sulfide Deposits ◽  
Almost All ◽  
Host Rocks ◽  
Low K ◽  
General Range

The Ansil massive sulfide deposit occurs at the contact of the underlying Northwest Rhyolite and the overlying Rusty Ridge Andesite, in the lower part of the Central Mine sequence of the Blake River Group. The orebody, which is roughly ellipsoidal in outline and up to 200 m × 150 m across, contained reserves of 1.58 Mt of massive sulfide grading 7.2% Cu, 0.9% Zn, 1.6 g/t Au, and 26.5 g/t Ag. Production began in 1989. Least-altered host rocks are low-K basaltic andesites and low-K rhyolites. These rocks have Zr/Y ratios of ~5 and LaN/YbN ratios of ~2.3, typical of tholeiitic volcanic rocks, although their major-element chemistry is transitional between tholeiitic and calc-alkaline volcanic rocks.The Ansil deposit, which dips ~50° east, is a single orebody comprising two main massive sulfide lenses (up to ~35 m thick) connected laterally via a thinner blanket of massive sulfides, with thin discontinuous but conformable massive magnetite units at the base and top of the orebody. Sulfide ore consists of massive to banded pyrrhotite–chalcopyrite. In the downplunge lens, up to 10 m of massive magnetite are capped by up to 10 m of massive sulfide. Finely banded cherty tuff, with sphalerite–pyrite–chalcopyrite, forms a discontinuous fringe to the deposit.The two main lenses of massive sulfide have the highest contents of Cu, Ag, and Au and are thought to have formed in areas of major hydrothermal input. Altered feeder zones contain either chlorite + chalcopyrite + pyrrhotite ± magnetite, or chlorite + magnetite ± sulfides. Footwall mineralization forms semiconformable zones ~5–10 m thick that directly underlie the orebody and high-angle pipelike zones that extend at least 50 m into the footwall. Ti–Zr–Al plots indicate that almost all altered footwall rocks were derived from a homogeneous rhyolite precursor. Hanging-wall andesites were also altered. Despite some severe alteration, all initial volcanic rock compositions can be readily identified, and thus mass changes can be calculated. Silica has been both significantly added or removed from the footwall, whereas K has been added except in feeder pipes. Oxygen-isotope compositions up to at least 50 m into the hanging wall and footwall are typically depleted in δ18O by 2–6‰. These rocks have gained Fe + Mg and lost Si. Altered samples in general range from light-rare-earth-element (REE) depleted to light-REE enriched, although some samples exhibit little REE modification despite strong alkali depletion. Mineralized volcanic rocks immediately below the orebody are enriched in Eu (as are some Cu-rich sulfides in the orebody).Contact and petrographic relations generally suggest that the main zone of massive magnetite formed by replacement of cp–po-rich sulfides, although local relations are ambiguous. Magnetite formation may reflect waning hydrothermal activity, during which fluids mixed with seawater and became cooler and more oxidized. Cu-rich feeder pipes that cut magnetite-rich footwall indicate a renewal of Cu-sulfide mineralization after magnetite deposition. Chloritic zones with disseminated sulfides occur up to a few hundred metres above the orebody, attesting to continuing hydrothermal activity.

scholarly journals Geologic interpretation of aeromagnetic and chemical data from the Oaks Belt, Wabigoon subprovince, Minnesota: implications for Au-rich VMS deposit exploration

2016 ◽  
Vol 53 (2) ◽  
pp. 176-188 ◽  
Author(s):  
Michael D. Hendrickson
Keyword(s):  
Base Metal ◽  
Volcanic Rocks ◽  
Correlation Coefficients ◽  
Massive Sulfide ◽  
Iron Formation ◽  
Geochemical Data ◽  
Volcanic Complex ◽  
Sulfide Deposits ◽  
Massive Sulfide Deposits ◽  
Subvolcanic Intrusion

The Oaks Belt (OB) is a Neoarchean volcanic complex located in northwestern Minnesota, USA. It is part of the Wabigoon granite–greenstone terrane that hosts the world-class Rainy River gold deposit in nearby Ontario, Canada. Rocks in the OB form a north-dipping homocline in the fault-bounded pressure shadow of a sigma-shaped volcano-plutonic wedge that spans east–west for 220 km across the Minnesota, USA – Ontario, Canada border. Exploration drilling in the area delineated pyrrhotite–pyrite massive sulfide deposits, iron formation, chert, and semi-massive sphalerite mineralized zones. High-resolution aeromagnetic data indicate a large (∼60 km2) composite subvolcanic intrusion underlies these iron-rich strata in the OB. The position of this inferred intrusion elucidates the low base metal content of known massive sulfide deposits, as they were too far away (6–10 km) from a heat source to have been favorable sites for base metal deposition. The relative abundance of Au and Zn in the OB, alongside correlation coefficients between metals in massive sulfide deposits, iron formation, and chert, indicates the rocks were affected by a low-temperature hydrothermal system under relatively shallow water conditions (<1000 m). Negative correlation between Na2O and CaO in basalt, and their mutual moderate positive correlation with immobile corundum (Al2O3), implies alteration in the upper part of the volcanic pile did not result in substantial element mobility in most samples. Geochemical data from mafic and felsic volcanic rocks plot mainly in the calc-alkaline field. Thus, the OB is most prospective for hosting Au-rich VMS deposits and future exploration should focus on paleo-thermal corridors and favorable stratigraphic horizons near the newly inferred composite subvolcanic intrusion.

Isotopic studies of ore-leads of the circum-Kisseynew volcanic belt of Manitoba and Saskatchewan

1978 ◽  
Vol 15 (7) ◽  
pp. 1112-1121 ◽  
Author(s):  
D. F. Sangster
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Massive Sulfide ◽  
Good Evidence ◽  
Lake Area ◽  
Sulfide Deposits ◽  
North West ◽  
The North ◽  
Isotopic Abundances ◽  
Host Rocks

Volcanic rocks, distributed to the north, west, and south of the Kisseynew gneissic belt in Manitoba and Saskatchewan, define a crescent-shaped belt herein informally referred to as the 'circum-Kisseynew volcanic belt'. Field relationships lead to the conclusion that the flanking volcanics are correlative with, and grade basinward to, greywackes and shales.Nearly 30 volcanogenic massive sulfide deposits, interpreted as coeval with their host rocks, are distributed throughout the circum-Kisseynew volcanic belt. Lead isotopic abundances in a representative number of these deposits are, apart from 204-error, relatively homogeneous in composition and model lead ages determined from these isotopic ratios fall, for the most part, between 1700 and 1900 Ma. This is regarded as good evidence that the circum-Kisseynew volcanic belt, as well as its greywacke equivalent, is largely Aphebian in age.Model lead ages for sulfide deposits from the entire circum-Kisseynew volcanic belt, with one exception, agree well with recent Rb–Sr and U–Pb age determinations from the southern portion of the belt. Reasons for the exception, in the Hanson Lake area, are discussed in some detail.

scholarly journals Geodynamic conditions of massive sulfide formation in the Magnitogorsk megazone

LITOSFERA ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 775-804
Author(s):  
A. М. Kosarev ◽  
V. N. Puchkov ◽  
Igor B. Seravkin ◽  
Gulnara T. Shafigullina
Keyword(s):  
Deep Structure ◽  
Volcanic Rocks ◽  
Massive Sulfide ◽  
Southern Urals ◽  
Island Arcs ◽  
The Southern Urals ◽  
Sulfide Deposits ◽  
Massive Sulfide Deposits ◽  
Deep Wells ◽  
Geodynamic Reconstructions

Research subject. Volcanism, rock geochemistry, geodynamics, and massive sulfide formation in the Magnitogorsk megazone (MMZ) of the Southern Urals in the Middle Paleozoic.Materials and Methods. Across the largest part of the massive sulfide deposits under investigation, the authors conducted route studies, including geological surveys of individual ore fields and quarries of deposits, core samples of deep wells and transparent sections. Representative analyses of petrogenic and microelements were performed using wet chemistry and ICP-MS in analytical centers in Russia and Europe. Along with the authors’ data, analytical materials published by Russian and foreign researchers were used. Geodynamic reconstructions were carried out taking into account regional data on gravics, thermal field, magnetometry, and seismic stu dies, including «Urseis-95».Results. The geodynamic reconstructions established that the main elements of the paleostructure of the Southern Urals in the Devonian were the subduction zone of the eastern dip and asthenospheric diapirs that penetrated into the «slab-window», which determined the type of volcanic belts, the composition and volume of volcanic rocks of pyrite-bearing complexes, and ore matter of pyrite deposits. The following geodynamic zones in the MMZ were identified: 1 – polychronous accretion prism; 2 – frontal and developed island arcs (D1e2–D2ef1); 3 – zone of back-arc spreading (D1e2); 4 – rear island arc (D2ef1).Conclusions. All investigated zones and ore areas are characterized by an autonomous development of volcanism, a special deep structure and a different composition, as well as by a different volume of massive sulfide deposits that vary in the Cu and Zn ratios and Pb, Ba, Au amounts. In the MMZ volcanic complexes, three groups of plume source basalts are distinguished. The results can be used in predictive-estimation and search operations for massive sulfide mineralization.

Massive sulfide deposits of the Noranda area, Quebec. II. The Aldermac mine

1991 ◽  
Vol 28 (9) ◽  
pp. 1301-1327 ◽  
Author(s):  
T. J. Barrett ◽  
S. Cattalani ◽  
F. Chartrand ◽  
P. Jones
Keyword(s):  
Volcanic Rocks ◽  
Parental Magma ◽  
Mass Gain ◽  
Massive Sulfide ◽  
Sulfide Deposit ◽  
Calc Alkaline ◽  
Sulfide Deposits ◽  
Massive Sulfide Deposits ◽  
Fractionation Trend ◽  
Felsic Volcanic

The original Aldermac mine near Noranda contained several Cu–Zn massive sulfide lenses hosted by felsic to mafic volcanic rocks of the late Archean Blake River Group. The original Nos. 3–6 orebodies, which consisted of massive pyrite, with lesser magnetite, pyrrhotite, chalcopyrite, and sphalerite, contained 1.87 Mt of Cu–Zn ore that averaged 1.47% Cu (Zn was not recovered). The orebodies occurred within felsic breccias and tuffs up to 100 m thick that are stratigraphically overlain by an extensive dome of mainly massive rhyolite and rhyodacite (up to 250 m thick and at least 550 m across). Most of the volcanic rocks that laterally flank and overlie the felsic dome are dacitic to andesitic flows, breccia, and tuff, with minor rhyolites, and associated subvolcanic sills of quartz-feldspar porphyry and gabbro.The new massive sulfide deposit, discovered in 1988, lies 150–200 m east of the mined-out orebodies, at a similar stratigraphic level within altered felsic breccia and tuff. The sulfides are mainly in the No. 8 lens, which contains 1.0 Mt at an average grade of 1.54% Cu, 4.12% Zn, 31.2 g/t Ag, and 0.48 g/t Au. Pyrite forms porphyroblastic megacrysts in a groundmass of pyrrhotite, sphalerite, magnetite, and chalcopyrite. A funnel-shaped, chloritized stockwork zone underlies the No. 8 lens and contains Cu-stringer mineralization. The No. 8 lens appears to be zoned, with overall decreasing Cu:Zn ratios from the core to the fringes of the lens. Massive sulfides in this lens have high Ag, Cd, and Hg contents relative to other massive sulfide deposits near Noranda.Ti versus Zr trends for least-altered Aldermac volcanic rocks indicate a more or less continuous magmatic fractionation trend ranging from high-Ti andesite to andesite, dacite, rhyodacite, and two distinct rhyolites (A and B). Most volcanic rocks were derived from a common parental magma that was transitional between tholeiitic and calc-alkaline compositions, as indicated by Ti–Y–Zr–Nb data and rare-earth-element distributions.Ti versus Zr trends in altered volcanic rocks indicate that silicification (mass gain) has affected some of the andesitic to rhyodacitic rocks, whereas chloritization (mass loss) has affected many of the rhyolitic rocks. Intermediate to mafic volcanic rocks above and lateral to the felsic dome are commonly silicified, possibly the result of hydrothermally remobilized silica derived from underlying felsic volcanic rocks.The orebodies appear to have formed at an eruptive hiatus between mafic → felsic and felsic → mafic cycles, during explosive activity and accumulation of felsic breccia and tuff. Ore was deposited mainly within a felsic fragmental sequence (rhyolite A), but before emplacement of the dome of rhyolite B. In compositionally diverse volcanic terrains, the contact between successive mafic–felsic and felsic–mafic cycles may be a good exploration target, in particular specific geochemical contacts within the felsic stratigraphy.

The Petrochemistry of Altered Volcanic Rocks Surrounding the Louvem Copper Deposit, Val d'Or, Quebec

1975 ◽  
Vol 12 (11) ◽  
pp. 1820-1849 ◽  
Author(s):  
Guy Spitz ◽  
Richard Darling
Keyword(s):  
Volcanic Rocks ◽  
Copper Deposit ◽  
Massive Sulfide ◽  
Original Compositions ◽  
Pyroclastic Rock ◽  
Calc Alkaline ◽  
Genetic Classification ◽  
Sulfide Deposits ◽  
Host Rocks

The Louvem copper deposit, a carrot-shaped body of mineralized silicic pyroclastic rock, appears generally conformable with surrounding, steeply dipping volcanic rocks, but otherwise closely resembles the cross-cutting feeder pipes that underlie many Archean stratiform volcanogenic massive sulfide deposits. It is, like many such deposits, associated with peraluminous and calc-alkaline rocks in the felsic upper portion of a volcanic sequence.Naming of the Louvem volcanic host rocks by means of their chemical composition is rendered difficult by intense local alteration which has changed their original compositions. Of the four classification schemes tried, that based on sample SiO2 content appears to provide results that are least affected by this alteration and which therefore reflect most clearly the original compositions of the rocks surrounding the ore deposit.The calc-alkaline nature of Louvem volcanic rocks is apparent even for very altered near-ore samples. This is revealed by Ol–Ne–Qz and AFM diagrams, which appear to be suitable for the genetic classification of such altered rocks.The chemical nature of the wallrock alteration in and around the deposit is revealed by certain petrologic diagrams. All rocks in the study area show magnesium enrichment, but no petrologic diagram illustrates this very clearly. Outside the orebody, the alteration consists mainly of Na and Ca depletion, and those diagrams which show such depletion are the most useful. Of these, the AKF, AFM, and ACF plots appear to be most practical.

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