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.

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.

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

The Origin of the Porphyry Deposit Name: From Shellfish, Tyrian Purple Dye, and Imperial Rome to the World’s Largest Copper Deposits

SEG Discovery ◽  
2019 ◽  
pp. 1-15
Author(s):  
Stewart D. Redwood
Keyword(s):  
Economic Geology ◽  
Porphyry Copper ◽  
Low Grade ◽  
Porphyry Copper Deposits ◽  
Igneous Petrology ◽  
Porphyry Deposit ◽  
Copper Deposits ◽  
Imperial Rome ◽  
Tyrian Purple ◽  
History Of

Abstract The porphyry deposit name has a long and fascinating etymological history of over 3,000 years. “Porphyry” is derived from the ancient Greek word porphyra (πoρϕύρα), or purple. It was originally applied to a rare purple dye, Tyrian purple, extracted by the Phoenicians from murex shells. It was later applied to a prized purple porphyritic rock, Imperial Porphyry or Porfido rosso attico, quarried by the Romans from Mons Porphyrites in the Eastern Red Sea hills of Egypt from the first to fifth centuries A.D., and used as a monumental stone in Imperial Rome and Byzantium (Istanbul). The name evolved in the field of igneous petrology to include all rocks with a porphyritic texture, regardless of their color. Mining of the first porphyry copper deposits, which were originally called disseminated or low-grade copper deposits, started in 1905. As a result of the close spatial and genetic relationship to porphyry stocks, they became known as porphyry copper deposits. The term was first used by W. H. Emmons in his 1918 textbook The Principles of Economic Geology, but it was originally used more as an engineering and economic description, as in Parsons’ 1933 book The Porphyry Coppers. It was slow to catch on in the geological literature. It was first used in the title of a paper in Economic Geology in 1947 but did not gain widespread use until the 1970s, following the publication of seminal papers on porphyry models and genesis by Lowell and Guilbert (1970) and Sillitoe (1972, 1973).

The Influence of CO2 on the Solubility of Quartz in Single-Phase Hydrothermal Fluids: Implications for the Formation of Stockwork Veins in Porphyry Copper Deposits

2019 ◽  
Vol 114 (6) ◽  
pp. 1195-1206 ◽  
Author(s):  
Thomas Monecke ◽  
Jochen Monecke ◽  
T. James Reynolds
Keyword(s):  
Single Phase ◽  
Porphyry Copper ◽  
Hydrothermal Systems ◽  
Hydrothermal Fluids ◽  
Gangue Mineral ◽  
Low Grade ◽  
Porphyry Copper Deposits ◽  
Copper Deposits ◽  
Co2 Concentrations ◽  
Quartz Solubility

Abstract Porphyry copper deposits consist of low-grade stockwork and disseminated sulfide zones that contain characteristic vein generations formed during the evolution of the hydrothermal systems. The present contribution examines the influence of variable CO2 concentrations on the solubility of quartz in single-phase hydrothermal fluids forming stockwork veins in porphyry deposits at temperatures of 150° to 550°C and pressures ranging from 100 to 2,000 bar at concentrations up to 8 mol % CO2. The calculations demonstrate that quartz solubility in hydrothermal fluids decreases with increasing CO2 content. Retrograde quartz solubility is less pronounced in CO2-bearing fluids and is not observed in single-phase fluids having CO2 concentrations exceeding 6 mol %. Despite the effects of CO2, retrograde quartz solubility plays an important role in the formation of porphyry stockwork veins that contain little or no quartz as a gangue mineral. At high temperatures and lithostatic pressure conditions below 900 bar, early biotite veins can form as a result of quasi-isobaric cooling of single-phase hydrothermal fluids under conditions of retrograde quartz solubility or near-constant quartz solubility. Stock-work veins consisting of molybdenite or hypogene copper sulfide minerals lacking quartz could form at temperatures of up to 450°C under hydrostatic pressures ranging from ~250 to 900 bar. In the presence of CO2, retrograde quartz solubility is shifted toward slightly lower temperatures at constant pressure. At temperatures below ≾375°C, quartz is precipitated during quasi-isobaric cooling irrespective of CO2 content of the hydrothermal fluids, resulting in the formation of late porphyry quartz veins.

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.

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