Sulfide Deformation Studies; I, Experimental Deformation of Pyrrhotite and Sphalerite to 2,000 Bars and 500 degrees C

Clark, Bruce R.; Kelly, William G.

doi:10.2113/gsecongeo.68.3.332

Cited by 82 publications

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“…Observations at Mobrun are consistent with the fact that sphalerite deforms ductilely under greenschist-facies metamorphic conditions (Clark and Kelly 1973), whereas pyrite undergoes brittle deformation (Atkinson 1975;Cox 1987). Where pyrite was in a matrix of sphalerite in the Mobrun orebodies, strain was accomodated by ductile flow of sphalerite, and pyrite was unaffected.…”

Section: Discussionsupporting

confidence: 62%

“…Under greenschist-facies metamorphic conditions, pyrite deforms exclusively by cataclasis (Atkinson 1975;Cox et al 1981). In contrast; chalcopyrite and * Present address: Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada sphalerite deform ductilely, by intragranular (dislocation) sliding and deformation twinning (Clark and Kelly 1973;Kelly and Clark 1975;Roscoe 1975). Pyrrhotite, which undergoes brittle deformation at low temperature and pressure, deforms ductilely by twin-gliding at temperatures above 250~ (Clark and Kelly 1973).…”

mentioning

confidence: 99%

“…Pyrrhotite, which undergoes brittle deformation at low temperature and pressure, deforms ductilely by twin-gliding at temperatures above 250~ (Clark and Kelly 1973). Interpretation of deformation textures may be made difficult by the fact that evidence of ductile deformation in sulfides may be obliterated by subsequent static (postdeformational) recrystallization or thermal annealing.…”

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confidence: 99%

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Effects of greenschist-facies metamorphism and related deformation on the Mobrun massive sulfide deposit, Qu�bec, Canada

Larocque

Hodgson

1995

Mineral. Deposita

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Abstract. The Mobrun Zn-Cu-Ag-Au deposit in the Noranda mining camp is hosted by Archean mafic and felsic submarine volcanic rocks. The deposit comprises three massive sulfide complexes: the Main and Satellite Lenses near surface, and the 1100 orebody at depth. The rocks have been subjected to lower greenschist-facies metamorphism and related deformation, which resulted in changes in ore textures, development of shear zones and veins systems, remobilization of gold, and formation of a new mineral (electrum) within the orebodies. Both mechanical and chemical processes operated to produce secondary textures and structures resulting from brittle deformation, ductile deformation, and annealing. The specific deformation mechanisms include brittle failure and cataclastic flow, dislocation glide, dislocation creep and solution-precipitation creep. The Main and Satellite Lenses are characterized by excellent preservation of primary sulfides deposited from and reworked by synvolcanic hydrothermal fluids. These orebodies were affected to a limited degree by mechanical processes of deformation. In contrast, the 1100 orebody is characterized by a higher degree of development of textures and structures related to metamorphism and deformation, especially those formed by chemical processes. The differences may be due to the greater depth of the 1100 orebody relative to the other lenses, as regional metamorphic isograds are subhorizontal, and more extensive interaction between metamorphic fluids and the 1100 Lens.Deformation experiments on natural polycrystalline sulfides have provided information on their mechanisms of deformation. Under greenschist-facies metamorphic conditions, pyrite deforms exclusively by cataclasis (Atkinson 1975;Cox et al. 1981). In contrast; chalcopyrite and * Present address: Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada sphalerite deform ductilely, by intragranular (dislocation) sliding and deformation twinning (Clark and Kelly 1973;Kelly and Clark 1975;Roscoe 1975). Pyrrhotite, which undergoes brittle deformation at low temperature and pressure, deforms ductilely by twin-gliding at temperatures above 250~ (Clark and Kelly 1973). Interpretation of deformation textures may be made difficult by the fact that evidence of ductile deformation in sulfides may be obliterated by subsequent static (postdeformational) recrystallization or thermal annealing. This is especially common in pyrrhotite.Examining the effects of deformation on monominerallic sulfide aggregates is useful, as it provides information about the relative importance of diffusion, slip, and intergranular deformation (Poirier 1985). However, the behaviour of individual sulfide minerals during metamorphism and related deformation of massive sulfide deposits may vary greatly, depending on temperature, strain rate, confining pressure, fluid pressure, differential stress, permeability within the zone of deformation, and the nature of adjacent or matrix-forming sulfides (Ashby and Verrall 1973;Kelly an...

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Section: Discussionsupporting

confidence: 62%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of greenschist-facies metamorphism and related deformation on the Mobrun massive sulfide deposit, Qu�bec, Canada

Larocque

Hodgson

1995

Mineral. Deposita

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“…This is depicted in Figure 9 where the differential stress at 10% strain is plotted vs. temperature and compared with data of similar experiments by Clark and Kelly (1973) and Atkinson (1975). The stress at 10% strain decreases with increasing temperature because CRSS decreases for the different glide modes ( X: Clark & Kelly 1973" (200 MPa, 7.2-10 -5 s4) : Atkinson 1975" (150 MPa, -3-10 -5 (Table 5 and Figure 10).…”

Section: Effect Of the Temperature And Strain Rate On The Flow Stressmentioning

confidence: 86%

“…Buerger 1928, Graf and Skinner 1970, Clark and Kelly 1973, Atkinson 1975, Kiibler 1985a (Niederschlag 1992). This is especially the case if only small changes are observed.…”

Section: Introductionmentioning

confidence: 99%

Influence of Initial Texture, Temperature and Total Strain on the Texture Development of Polycrystalline Pyrrhotite Ores in Deformation Experiments

Niederschlag¹,

Siemes

1996

Texture, Stress, and Microstructure

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The development of the crystallographic preferred orientation (texture) of polycrystalline pyrrhotite from Sullivan mine, Canada, and Cerro de Pasco, Peru was determined by neutron texture analyses before and after experimental deformation. The pyrrhotite ore from Sullivan has an initial texture with a distinct c-axis maximum perpendicular to the foliation whereas the ore from Cerro de Pasco shows a weak and moreover inhomogeneous texture within the specimen.The deformation texture and deformation behaviour of samples from Sullivan were investigated as a function of temperature, total strain and the angle between the compression axis and the initial caxis maximum. The deformation textures show the influence of different activated glide modes as a function of the compression direction and temperature. Investigations of the deformation texture and deformation behaviour of samples from Cerro de Pasco were carded out as a function of temperature, total strain and strain rate. The inhomogeneous texture of the starting material did not allow to draw conclusions about the texture development as a function of strain rate and temperature. Nevertheless the preferred orientation of the c-axes parallel to the compression axis becomes more evident with increasing total strain.

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Table 1 (norite - tuff)

Rummel¹

Landolt-Börnstein - Group v Geophysics

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Sulfide Deformation Studies; I, Experimental Deformation of Pyrrhotite and Sphalerite to 2,000 Bars and 500 degrees C

Cited by 82 publications

References 0 publications

Effects of greenschist-facies metamorphism and related deformation on the Mobrun massive sulfide deposit, Qu�bec, Canada

Effects of greenschist-facies metamorphism and related deformation on the Mobrun massive sulfide deposit, Qu�bec, Canada

Influence of Initial Texture, Temperature and Total Strain on the Texture Development of Polycrystalline Pyrrhotite Ores in Deformation Experiments

Table 1 (norite - tuff)

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