Evidence from lead isotopes regarding the genesis of ore deposits in the Chibougamau region, Quebec

1981 ◽  
Vol 18 (4) ◽  
pp. 708-723 ◽  
Author(s):  
R. I. Thorpe ◽  
Jayanta Guha ◽  
Jules Cimon
Keyword(s):  
Lead Isotopes ◽  
Spatial Association ◽  
Massive Sulfide ◽  
Gold Deposits ◽  
Ore Deposits ◽  
Carbonate Sediments ◽  
Sulfide Deposits ◽  
Copper Gold ◽  
Genesis Of Ore Deposits ◽  
Isotope Analyses

Twenty-three lead isotope analyses are reported for massive sulfide deposits, the main copper–gold shear zone deposits in anorthosite of the Doré Lake complex, and two gold deposits, all in Archean terrane, in the Chibougamau district. Five analyses were also obtained for lead occurrences in Proterozoic carbonate sediments in the Mistassini Basin.Galenas from the Coniagas and Lemoine deposits of volcanogenic massive sulfide type, from the Taché Lake deposit of possibly the same type, from the Norbeau and Ayrhart gold properties, and one from within the Opemiska mine, have Archean compositions. Of these, the Lemoine, Norbeau, and Opemiska mine galenas are slightly younger than the others or were contaminated during later deformation and (or) metamorphism.Analyses for the main Cu–Au deposits generally form a cluster, although the spread in 206Pb/204Pb ratios is significant and three analyses for the Copper Rand deposit, in particular, are distinct from data for the other deposits. One interpretation is that the data, in combination with the Archean analyses, define a secondary isochron reflecting a primary age of Archean deposits and rocks at 2735–2800 Ma and a secondary event, including genesis of the Cu–Au ores, at 2240–2160 Ma. Additional evidence for a metamorphic–plutonic(?) event at about 2200 Ma has been provided by previous paleomagnetic studies. One galena from the Opemiska deposit appears to have had uranogenic lead added at 1735–2075 Ma. Three analyses of galena from the Campbell (Merrill) pit are anomalous or indicate they were formed at 162–300 Ma, and it is suggested they may have resulted from multiple episodic additions of ambient rock lead to galena originally deposited at about 2200 Ma.Two new analyses, together with four older values, for Mistassini Basin lead occurrences define a possible secondary isochron that may indicate an integrated source age of 2655 or 2940 Ma at mineralization ages of 2100 and 1700 Ma, respectively. This secondary isochron is very poorly defined because three other new analyses plot above the line.This study suggests that further geochronological investigation of the Cu–Au orebodies, and of felsic dykes that occur in many cases in close spatial association with them, should be undertaken.

Gold Exploration and Potential of the Appalachian Piedmont of Eastern Alabama

SEG Discovery ◽  
2013 ◽  
pp. 1-17
Author(s):  
Jim Saunders ◽  
Mark Steltenpohl ◽  
Robert B. Cook
Keyword(s):  
Massive Sulfide ◽  
Gold Deposits ◽  
Southern Appalachians ◽  
Sulfide Deposits ◽  
Gold Exploration ◽  
Geochemical Association ◽  
Carolina Slate Belt ◽  
Appalachian Piedmont ◽  
Metamorphic Terranes ◽  
Exploration Activity

ABSTRACT: The discovery and production of gold from epithermal and volcanogenic massive sulfide deposits in the Carolina slate belt of the southern Appalachians perhaps have overshadowed the gold potential of orogenic gold deposits in relatively higher grade metamorphic terranes of the southern Appalachian Piedmont. There has been a limited amount of exploration in the non-Carolina slate belt southern Appalachians since the early 1980s. Here we describe some of the recent exploration activity and geology of gold occurrences in the most productive part of the Alabama Piedmont, including the Goldville and Devil’s Backbone districts. In this area, there is a strong geochemical association of gold and arsenic in bedrock, saprolite, and soils, which reflects the mineralogical association of gold with arsenian pyrite and arsenopyrite in mineralized zones.

Subduction, mantle metasomatism, and gold: A dynamic and genetic conjunction

2019 ◽  
Vol 132 (7-8) ◽  
pp. 1419-1426 ◽  
Author(s):  
David I. Groves ◽  
Liang Zhang ◽  
M. Santosh
Keyword(s):  
Subduction Zones ◽  
Massive Sulfide ◽  
Mantle Metasomatism ◽  
Gold Deposits ◽  
Genetic Models ◽  
Dynamic Factor ◽  
Convergent Margins ◽  
Copper Gold ◽  
Orogenic Cycle ◽  
Fluid Release

Abstract Global gold deposit classes are enigmatic in relation to first-order tectonic scale, leading to controversial genetic models and exploration strategies. Traditionally, hydrothermal gold deposits that formed through transport and deposition from auriferous ore fluids are grouped into specific deposit types such as porphyry, skarn, high- and low-sulfidation–type epithermal, gold-rich volcanogenic massive sulfide (VMS), Carlin-type, orogenic, and iron-oxide copper-gold (IOCG), and intrusion-related gold deposits (IRGDs). District-scale mineral system approaches propose interrelated groups such as porphyry Cu-Au, skarn Cu-Au-Ag, and high-sulfidation Au-Ag. In this study, the temporal evolution of subduction-related processes in convergent margins was evaluated to propose a continuum of genetic models that unify the various types of gold deposits. At the tectonic scale of mineral systems, all hydrothermal gold deposits are interrelated in that they formed progressively during the evolution of direct or indirect subduction-related processes along convergent margins. Porphyry-related systems formed initially from magmatic-hydrothermal fluids related to melting of fertile mantle to initiate calc-alkaline to high-K felsic magmatism in volcanic arcs directly related to subduction. Formation of gold-rich VMS systems was related to hydrothermal circulation driven by magmatic activity during rifting of oceanic arcs. Orogenic gold deposits formed largely through fluids derived from devolatilization of the downgoing slab and overlying sediment wedge during late transpression in the orogenic cycle. Carlin-type deposits, IRGDs, and some continental-arc porphyry systems formed during the early stages of orogenic collapse via fluids directly or indirectly related to hybrid magmatism from melting of lithosphere that was metasomatized and gold-fertilized by earlier fluid release from subduction zones near margins of continental blocks. The IOCGs were formed during postorogenic asthenosphere upwelling beneath such subduction-related metasomatized and fertilized lithospheric blocks via fluid release and explosive emplacement of volatile-rich melts. Thus, importantly, subduction is clearly recognized as the key unifying dynamic factor in gold metallogenesis, with subduction-related fluids or melts providing the critical ore components for a wide variety of gold-rich deposit types.

scholarly journals Highly Metalliferous Potential of Framboidal and Nodular Pyrite Varieties from the Oil-Bearing Jurassic Bazhenov Formation, Western Siberia

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 449
Author(s):  
Kirill S. Ivanov ◽  
Valery V. Maslennikov ◽  
Dmitry A. Artemyev ◽  
Aleksandr S. Tseluiko
Keyword(s):  
Oil And Gas ◽  
Massive Sulfide ◽  
Global Scale ◽  
Ore Deposits ◽  
Black Shales ◽  
Ural Mountains ◽  
Sulfide Deposits ◽  
Bazhenov Formation ◽  
Zn And Cu In ◽  
Positive Correlations

In the Bazhenov Formation, framboidal clusters and nodular pyrite formed in the dysoxic–anoxic interface within organic-rich sediments. Some nodule-like pyritized bituminous layers and pyrite nodules are similar to pyritized microbial mat fragments by the typical fine laminated structure. Framboidal pyrite of the Bazhenov Formation is enriched in redox-sensitive elements such as Mo, V, Au, Cu, Pb, Ag, Ni, Se, and Zn in comparison with the host shales and nodular pyrite. Nodular pyrite has higher concentrations of As and Sb, only. Strong positive correlations that can be interpreted as nano-inclusions of organic matter (Mo, V, Au), sphalerite (Zn, Cd, Hg, Sn, In, Ga, Ge), galena (Pb, Bi, Sb, Te, Ag, Tl), chalcopyrite (Cu, Se) and tennantite (Cu, As, Sb, Bi, Te, Ag, Tl) and/or the substitution of Co, Ni, As and Sb into the pyrite. On the global scale, pyrite of the Bazhenov Formation is very similar to pyrite from highly metalliferous bituminous black shales, associated, as a rule, with gas and oil-and-gas deposits. Enrichment with Mo and lower Co and heavy metals indicate a higher influence of seawater during formation of pyrite from the Bazhenov Formation in comparison to different styles of ore deposits. Transitional elements such as Zn and Cu in pyrite of the Bazhenov Formation has resulted from either a unique combination of the erosion of Cu–Zn massive sulfide deposits of the Ural Mountains from one side and the simultaneous manifestation of organic-rich gas seep activity in the West Siberian Sea from another direction.

Lead- and strontium-isotope geochemistry of Paleozoic Sicker Group and Jurassic Bonanza Group volcanic rocks and Island Intrusions, Vancouver Island, British Columbia

1989 ◽  
Vol 26 (5) ◽  
pp. 894-907 ◽  
Author(s):  
Anne Andrew ◽  
Colin I. Godwin
Keyword(s):  
Lead Isotope ◽  
Isotope Geochemistry ◽  
Lead Isotopes ◽  
Volcanic Rocks ◽  
Isotope Ratios ◽  
Ore Deposits ◽  
Island Arc ◽  
Lead Isotope Ratios ◽  
Rock Suite ◽  
Isotope Analyses

Whole-rock and galena lead-isotope analyses have been obtained from the Sicker Group Paleozoic island-arc volcanic package and from a Jurassic island-arc represented by the Bonanza Group volcanics and Island Intrusions. Galena lead-isotope analyses from the volcanogenic ore deposits at the Buttle Lake mining camp in the Sicker Group provide estimates of the initial lead ratios for the Sicker Group. Lead-isotope signatures are uniform within each of the major orebodies, but the Myra orebody is less radiogenic than the older H–W orebody. This has major significance in terms of ore genesis for these important deposits.There are significant differences in isotopic composition between the Sicker Group and Devonian island-arc type rocks in the Shasta district, California, which rules out direct correlations between the rock units of these two areas. Relatively high initial values of 207Pb/204Pb (> 15.56) and 208Pb/204Pb (> 38.00) suggest that large quantities of crustal lead must have been involved in the formation of the Sicker Group volcanic rocks. Thus it is proposed that the trench related to the Paleozoic island arc had a substantial input of continental detritus and may have lain near a continent.The Jurassic island arc is characterized by low 207Pb/204Pb ratios (< 15.59), suggesting a more primitive arc environment than for the Paleozoic arc. Bonanza Group volcanic rocks contain lead that is less radiogenic than lead in the Island Intrusions. Present and initial lead-isotope ratios of both the Bonanza Group volcanics and Island intrusions follow the same trend, supporting the hypothesis that they are comagmatic. Lead isotopes from a galena vein within the Island Copper porphyry deposit plot with the initial ratios for Bonanza Group volcanics and Island Intrusions. This confirms the hypothesis that this mineralization is related to the Jurassic island-arc volcanic event.Initial lead-isotope ratios for the Jurassic rock suite form a linear array on both 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb plots. If interpreted as due to isotopic mixing, the more radiogenic end member has a composition that is lower in 207Pb/204Pb and higher in 206Pb/204Pb than typical upper continental crust. Assimilation of Sicker Group material during the emplacement of the Jurassic arc can explain the mixing trend.

Mineral Deposits of Myanmar (Burma)

10.5382/gb.62 ◽  
2021 ◽  
Author(s):  
Laurence Robb ◽  
Andrew Mitchell
Keyword(s):  
Massive Sulfide ◽  
Gold Deposits ◽  
Late Triassic ◽  
Mineral Deposits ◽  
Magmatic Arc ◽  
Silver Deposits ◽  
Copper Gold ◽  
Lead Zinc ◽  
Lead Nickel ◽  
Complex Geology

Myanmar is richly endowed in natural resources that include tin, tungsten, copper, gold, zinc, lead, nickel, and silver, as well as gemstones. The material covered over a nine-day field trip explores the country’s complex geology, which reflects a collisional history stretching from the Late Triassic to at least Miocene, sited at the eastern end of the India-Asia suture. The country can be divided into three principal metallotects: the Wuntho-Popa magmatic arc, with granites and associated porphyry-type and epithermal Cu-Au mineralization; the Slate Belt (also called the Mogok-Mandalay-Mergui Belt), with multiple precollisional I-type and postcollisional S-type crustal melt granites that host significant tin-tungsten mineralization, and which also are host to a number of orogenic gold deposits; and the Shan Plateau with massive sulfide-type and also MVT-style lead-zinc-silver deposits.

A Special Issue on Archean Magmatism, Volcanism, and Ore Deposits: Part 2. Volcanogenic Massive Sulfide Deposits Preface,

2013 ◽  
Vol 109 (1) ◽  
pp. 1-9 ◽  
Author(s):  
P. Mercier-Langevin ◽  
H. L. Gibson ◽  
M. D. Hannington ◽  
J. Goutier ◽  
T. Monecke ◽  
...  
Keyword(s):  
Massive Sulfide ◽  
Ore Deposits ◽  
Special Issue ◽  
Volcanogenic Massive Sulfide ◽  
Sulfide Deposits ◽  
Massive Sulfide Deposits ◽  
Volcanogenic Massive Sulfide Deposits

Compositional peculiarities of the host rocks and ores of the Lazursky ore field, Zmeinogorsk ore region of the Rudny Altai minerogenic zone

2021 ◽  
pp. 36-47
Author(s):  
Tatyana SERAVINA ◽  
Svetlana KUZNETSOVA ◽  
Ludmila FILATOVA
Keyword(s):  
Massive Sulfide ◽  
Ore Deposits ◽  
Sulfide Ores ◽  
Volcanogenic Massive Sulfide ◽  
Sulfide Deposits ◽  
Ore Bodies ◽  
Ore Minerals ◽  
Copper Pyrite ◽  
Host Rocks ◽  
Volcanogenic Massive Sulfide Deposits

The article describes composition of the host rocks and ores of the Lazursky and Maslyansky polymetallic volcanogenic massive sulfide deposits of the Lazursky ore field located within the Zmeinogorsk ore region of the Rudny Altai minerogenic zone. The ore field is composed of various facies of the Devonian (Late Givetian – Frasnian) ore-bearing siliceous-terrigenous basalt-rhyolite formation containing horizons of synvolcanic metasomatites. All rocks of the ore field were subjected to folding and schistosity with zones of tectonic brecciation. Hydrothermal alterations are represented by carbonatization and chloritization. The ore bodies exposed at the Lazursky and Maslyansky ore deposits are represented by copper-pyrite, copper, and zinc-copper-pyrite massive sulfide ores and other varieties. The major ore minerals of the deposits are chalcopyrite, pyrite, sphalerite, marcasite, and pyrrhotite.

Chapter 1: Gold Deposit Types: An Overview

2020 ◽  
pp. 1-28
Author(s):  
Richard H. Sillitoe
Keyword(s):  
Gold Deposit ◽  
Unknown Origin ◽  
Mafic Magma ◽  
Massive Sulfide ◽  
Gold Deposits ◽  
Hydrothermal Fluids ◽  
Copper Gold ◽  
Deposit Type ◽  
Ambient Surface

Abstract Gold is either the only economically important metal or a major by-product in 11 well-characterized deposit types—paleoplacer, orogenic, porphyry, epithermal, Carlin, placer, reduced intrusion related, volcanogenic massive sulfide (VMS), skarn, carbonate replacement, and iron oxide-copper-gold (IOCG), arguably more than for those of any other metal; it also dominates a number of deposits of uncertain or unknown origin. Major gold concentrations formed worldwide from the Mesoarchean to the Pleistocene, from Earth’s surface to midcrustal paleodepths, alone or in association with silver, base metals, and/or uranium, and from hydrothermal fluids of predominantly metamorphic, magmatic, meteoric, seawater, or, uncommonly, basinal origins, as well as from mafic magma or ambient surface water. Most of the Neoproterozoic and Phanerozoic deposits unequivocally formed in accretionary orogens. As an introduction to this compilation of the world’s major gold deposits and provinces, this paper provides a thumbnail sketch of each gold deposit type, including geologic and economic characteristics and widely accepted genetic models, as well as briefly discusses aspects of their spatial and temporal associations and distributions.

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