A thermodynamic approach to the understanding of the supergene alteration at the Afton copper mine, south-central British Columbia

1982 ◽  
Vol 19 (12) ◽  
pp. 2378-2386 ◽  
Author(s):  
Y. T. J. Kwong ◽  
T. H. Brown ◽  
H. J. Greenwood
Keyword(s):  
British Columbia ◽  
Extreme Values ◽  
Porphyry Copper ◽  
Copper Oxides ◽  
Thermodynamic Approach ◽  
Porphyry Copper Deposits ◽  
Native Copper ◽  
Copper Mine ◽  
Supergene Zone ◽  
South Central

A thermodynamic reconstruction of the supergene alteration at the Afton copper mine, south-central British Columbia, demonstrates that the dominance of native copper and the lack of copper enrichment in the supergene zone are related to the relatively mafic composition of the wall rocks and the absence of abundant hypogene sulfides. Supergene alteration of porphyry copper deposits in general can be interpreted in terms of a [Formula: see text] plot. Two arbitary "limiting" curves characterized by extreme values of acidic and basic pH can be drawn. A reacting fluid evolving near the acidic limiting curve will produce a well developed leached cap with an enriched supergene ore blanket underneath. In contrast, a reacting fluid evolving near the basic limiting curve will lead to a spectrum of copper oxides and native copper with little enrichment, as typified by Afton.

Seismic and potential‐field imaging of the Guichon Creek batholith, British Columbia, Canada, to delineate structures hosting porphyry copper deposits

Geophysics ◽  
2000 ◽  
Vol 65 (5) ◽  
pp. 1418-1434 ◽  
Author(s):  
Baishali Roy ◽  
Ron M. Clowes
Keyword(s):  
British Columbia ◽  
Seismic Reflection ◽  
Porphyry Copper ◽  
Regional Scale ◽  
Low Grade ◽  
Depth Range ◽  
Porphyry Copper Deposits ◽  
Near Surface ◽  
Copper Deposits ◽  
South Central

The Guichon Creek batholith (GCB), located in south‐central British Columbia, contains several large, low‐grade copper deposits of considerable economic importance. The surface geology of the Guichon batholith and its surrounding region have been well mapped; however, little information about subsurface features is available. The batholith consists of four major phases, emplaced radially outward, which can be separated on the basis of their texture and composition. Previous interpretation of gravity data suggests a mushroom‐shaped structure for the batholith. Data from Lithoprobe seismic reflection line 88-11, acquired across the batholith in 1988, reveal weakly coherent east‐dipping reflections on the west side and west‐dipping reflections on the east in the upper 10 km. To determine if these are related to structures associated with the batholith, we reprocessed the upper 6 s with particular emphasis on applications of signal enhancement techniques (e.g., pattern recognition methods, refraction statics, dip moveout corrections) and correlation of the improved subsurface images with the geological environment associated with porphyry copper deposits. Low near‐surface velocities correlate well with the phases of the batholith hosting the major copper deposits, which structurally lie in faulted and brecciated regions. Although the top 1.5 km cannot be imaged by the regional‐scale seismic reflection data, the reprocessed seismic section helps define the edges of the batholith, its various concentric phases, and the stem in the depth range of 1.5 to 10 km. The seismic results are complemented by 2.5-D (profile sense) modeling and 3-D inversion of regional‐scale gravity and high‐resolution aeromagnetic data. These show a low‐density and low‐magnetic‐susceptibility region associated with the batholith that extends to more than 10 km depth. The region of active mining interest lies above a circular low‐susceptibility area at 2 km depth and a low‐velocity region. Integrated interpretation of geophysical results and geological observations indicates the GCB is a funnel‐shaped feature in which mineralization is located above the stem of the batholith.

Precontact Native Copper Innovation in British Columbia

2020 ◽  
Vol 44 (2) ◽  
pp. 185-122
Author(s):  
H. Kory Cooper ◽  
Garett Hunt ◽  
Nicholas Waber ◽  
Carey Gray
Keyword(s):  
British Columbia ◽  
Additional Research ◽  
Northwest Coast ◽  
Native Copper ◽  
Behavioral Archaeology ◽  
South Central ◽  
Wide Perspective ◽  
Final Verdict ◽  
Human Burials ◽  
And Diffusion

Copper has figured prominently in discussions of social complexity among Northwest Coast Cultures. Coppers, shield-like sheets of copper variable in size, were a form of lineage wealth displayed, gifted, or ritually destroyed at potlatches; and copper artifacts have been recovered from human burials. The former use of copper is well-documented ethnographically and historically while the latter phenomenon is less well understood. This paper provides an overview of the occurrence of copper in precontact archaeological contexts in British Columbia using published and unpublished literature. Our investigation is framed within a Behavioral Archaeology approach that elicits ideas on copper innovation and all that it entailed. We find that copper is rare in precontact contexts from a province-wide perspective; there was likely more than one instance of native copper innovation; and contrary to previous suggestions, the copper-rich Dene region of south-central Alaska and southwestern Yukon cannot account for most of the precontact examples of copper use in the province. We offer some hypotheses to explain the precontact distribution of copper in BC, including both local invention and diffusion, not in an attempt to deliver the final verdict on this topic, but rather, to stimulate additional research.

The Origin of Sheet Fractures in the Galore Creek Copper Deposits, British Columbia

1971 ◽  
Vol 8 (6) ◽  
pp. 704-711 ◽  
Author(s):  
Donald G. Allen
Keyword(s):  
British Columbia ◽  
Hydrothermal Alteration ◽  
Porphyry Copper ◽  
Surface Feature ◽  
Porphyry Copper Deposits ◽  
Volume Increase ◽  
Copper Deposits ◽  
Feature Characteristic

A surface feature characteristic of the Galore Creek copper deposits is a set of well-developed closely-spaced fractures, termed sheet fractures. The formation of these fractures is attributed to the widespread presence of anhydrite, a hydrothermal alteration mineral associated with copper. The fractures apparently developed as a consequence of the volume increase due to hydration of the anhydrite to gypsum by meteoric water.The Galore Creek deposits have many characteristics of porphyry copper deposits, in many of which anhydrite or gypsum has been reported. Anhydrite may be responsible for the development of sheet fractures elsewhere.

scholarly journals RECOGNIZING PORPHYRY COPPER POTENTIAL FROM TILL ZIRCON COMPOSITION: A CASE STUDY FROM THE HIGHLAND VALLEY PORPHYRY DISTRICT, SOUTH-CENTRAL BRITISH COLUMBIA

2021 ◽  
Author(s):  
Robert G. Lee ◽  
Alain Plouffe ◽  
Travis Ferbey ◽  
Craig J.R. Hart ◽  
Pete Hollings ◽  
...  
Keyword(s):  
British Columbia ◽  
Trace Element ◽  
Detrital Zircon ◽  
Porphyry Copper ◽  
Detrital Zircons ◽  
Late Triassic ◽  
Ionization Mass ◽  
South Central ◽  
Copper Mineralization ◽  
Porphyry Copper Mineralization

Abstract The detrital zircons in tills overlying the Guichon Creek batholith, British Columbia, Canada, have trace element concentrations and ages similar to those of zircons from the bedrock samples from which they are interpreted to have been sourced. Rocks from the core of the batholith that host porphyry copper mineralization have distinct zircon compositions relative to the distal, barren margin. We analyzed 296 zircons separated from 12 subglacial till samples to obtain U-Pb ages and trace element compositions. Laser ablation U-Pb ages of the detrital zircons overlap within error with chemical abrasion-thermal ionization mass spectrometry U-Pb ages of the Late Triassic Guichon Creek batholith and confirm that the detrital zircons are likely derived from the batholith. The youngest intrusions of the batholith produced the Highland Valley Copper porphyry deposits and contain distinctive zircons with elevated Eu/EuN* >0.4 attributed to high magmatic water contents and oxidation states, indicating higher porphyry copper potential. Zircon from till samples adjacent to and 9 km down-ice from the mineralized centers have mean Eu/EuN* >0.4, which are indicative of potential porphyry copper mineralization. Detrital zircon grains from more distal up- and down-ice locations (10–15 km) have zircon Eu/EuN* mean values of 0.26 to 0.37, reflecting background values. We conclude that detrital zircon compositions in glacial sediments transported several kilometers can be used to establish the regional potential for porphyry copper mineralization.

Fluid inclusion geochemistry of the Granisle and Bell porphyry copper deposits, British Columbia

1980 ◽  
Vol 75 (1) ◽  
pp. 45-61 ◽  
Author(s):  
J. W. J. Wilson ◽  
S. E. Kesler ◽  
P. L. Cloke ◽  
W. C. Kelly
Keyword(s):  
British Columbia ◽  
Fluid Inclusion ◽  
Porphyry Copper ◽  
Porphyry Copper Deposits ◽  
Copper Deposits

Geochronology of mid-Cretaceous to Eocene magmatism, Babine porphyry copper district, central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 639-655 ◽  
Author(s):  
D G MacIntyre ◽  
M E Villeneuve
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Porphyry Copper ◽  
Volcanic Rocks ◽  
Porphyry Copper Deposits ◽  
Isotopic Dating ◽  
Plate Convergence ◽  
Copper Mineralization ◽  
Porphyry Copper Mineralization ◽  
Magmatic Event

New U/Pb and 40Ar/39Ar isotopic dating in the Babine porphyry copper district of central British Columbia documents three distinct magmatic events at 107–104, 85–78, and 54–50 Ma. The earliest event involved emplacement of rhyolite domes into submarine volcanic rocks of the Rocky Ridge Formation. The rhyolite domes and related dacitic to basaltic volcanic rocks gave a U–Pb age of 107.9 ± 0.2 Ma and an 40Ar/39Ar age of 104.8 ± 1.2 Ma. The rhyolites, which were previously mapped as Eocene, are reinterpreted to be part of a previously unrecognized mid-Cretaceous cauldron subsidence complex. The regionally extensive Late Cretaceous magmatic event is also recognized in the Babine district and is represented by 40Ar/39Ar ages of 85.2 ± 2.8 and 78.3 ± 0.8 Ma on two Bulkley intrusions, one of which has associated porphyry copper mineralization. The final magmatic event is the most widespread and involved emplacement of the Babine intrusions and formation of numerous porphyry copper deposits including the Bell and Granisle past producers. Twenty-one new 40Ar/39Ar isotopic ages for these intrusions and coeval andesites of the Newman Formation have a narrow range from 53.6 ± 0.9 to 49.9 ± 0.6 Ma, whereas previous K–Ar isotopic dating had a possible range of 15 Ma. The mid-Cretaceous, Late Cretaceous, and Eocene magmatic suites in the Babine district are interpreted to be part of a long-lived volcano-plutonic complex that was the site of periodic magmatism and porphyry copper mineralization over a 60 Ma time period. This complex may have evolved within a zone of extension (pull-apart basins) situated between dextral strike-slip faults that were active during periods of rapid oblique plate convergence.

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