Geology of the Gondor volcanogenic massive sulphide deposit, Slave Province, N.W.T.

Abstract The Gondor Zn-Ag-Pb-Cu deposit is a stratabound massive sulphide lens occurring within Archean volcanidastic rocks of the Yellowknife Supergroup. The deposit is located in the west-central portion of the Slave Structural Province, approximately 350 km north of Yellowknife. Initial diamond drilling at Gondor has outlined a steeply-dipping, L-shaped, folded, massive sulphide body, which may be traced over a strike length of approximately 800 m, and to a depth of 350 m. True widths of up to 40 m have been intersected in the thickest part of the deposit. Preliminary estimates suggest that the deposit contains a minimum of 7.5 million tonnes grading 6% Zn, 50 g/tonne Ag and less than 1 % combined Cu and Pb. In addition, significant gold, grading up to 2.8 g/tonne, occurs in some parts of the deposit. The mineralization is open both down-dip and along strike.
The Gondor deposit lies conformably within a predominantly east-west striking, north-facing sequence of felsic to intermediate volcanidastic rocks. Coarse fragmental rocks are abundant in the hanging wall, whereas ash and lapilli-tuffs predominate in thefootwall. The main structural feature in the area is a large-scale, steeply northeast-plunging, Z-shaped fold. The sulphide mineralization lies within the synformal portion of this fold, with the thickest part of the deposit coinciding with its hinge zone. Several episodes of faulting have also affected the local stratigraphy.
The wallrocks of the Gondor deposit were hydrothermally altered prior to the onset of medium-grade regional meta-morphism. A halo of altered rocks surrounds the massive sulphide lens, with no apparent difference in the degree of alteration between the hanging wall and footwall strata. The alteration zone is characterized by the addition of MgO and K2O and by the depletion of Na2O and CaO. These changes are reflected in the mineralogy of the altered wallrocks by local enrichment in chlorite, biotite, muscovite and cordierite.
The mineralized zone is medium- to coarse-grained, well-banded and is composed largely of pyrite, quartz, and sphalerite with subordinate galena and chalcopyrite. Preliminary studies of metal distribution indicate that a lateral zonation is present, with lead enrichment in the central part of the deposit, and copper enrichment toward both ends. Stringer-type copper mineralization has not yet been discovered in thefootwall of the Gondor deposit.
Keywords: Mineral exploration, Geology, Massive sulphide deposits, Gondor deposit, Slave Province, Drilling, Wallrock alteration, Stratigraphy.
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Summary: A helicopter-borne geophysical survey was flown in 1978 over selected areas on Kyushu Island, Japan. The principal sensors were a moving source electro-magnetic system and a magnetometer. Maps of apparent resistivity were generated from the EM data. Based on the resistivity signature of known deposits within the survey areas, targets were selected for ground follow-up. Drilling of one such target in late 1980 resulted in the discovery of a gold deposit from which full production will begin in...
Publication: CIM Bulletin
Author(s): IAN M. JOHNSON, MINORU FUJITA
Keywords: Mineral exploration, Electromagnetic survey, Drilling, Gold deposits, Geophysics, Hishikari gold deposits.
Issue: 876
Volume: 78
Year: 1985
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Summary: The world's first zinc pressure leaching plant at Cominco's Trail operations started production in 1981. Sullivan zinc concentrate is leached at the rate of 190 tpd in a four-compartment autoclave at elevated temperatures and oxygen pressures to produce a zinc sulphate solution and elemental sulphur. Zinc extraction exceeds 98% and sulphide to elemental sulphur conversion exceeds 95%.
The sulphur is recovered from the discharged slurry in the underflow of a hydrocyclone, and is upgraded as a...
Publication: CIM Bulletin
Author(s): M.T. MARTIN, W.A. JANKOLA
Keywords: Extractive metallurgy, Zinc pressure leaching plant, Zinc, Pressure leaching, Sulphur recovery, Flotation.
Issue: 876
Volume: 78
Year: 1985
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Summary: Zonation patterns are well developed in the mafic meta-volcanic rocks that host epigenetic quartz-carbonate-gold vein mineralization at the Hollinger-Mclntyre deposit. Carbonate alteration assemblages are strongly zoned about mineralization. Proceeding inward from background greenschist fades rocks to alteration envelopes enclosing individual veins, the following assemblages are observed: Assemblage I—quartz-albite-chlorite-epidote-actinolite-(calcite) Assemblage II—quartz-albite-...
Publication: CIM Bulletin
Author(s): TED J. SMITH, STEPHEN E. KESLER
Keywords: Mineral exploration, Fluid inclusion, Geochemistry, Wallrock alteration, Gold mineralization, Zoning patterns, Trace elements, Economic geology
Issue: 876
Volume: 78
Year: 1985
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Summary: A test surface Pulse EM(PEM) survey over a plunging massive sulphide lens, located in the Snow Lake area of Manitoba, has shown that it is possible to detect the body to a depth of 300 metres. Another surface survey in the Athabasca basin of Saskatchewan, clearly outlined a large, basement graphitic zone below 450 metres of sandstone cover. Deep detection of these conductive bodies was achieved by energizing large volumes of ground with a strong transmitted EM field. Such large fields also...
Publication: CIM Bulletin
Author(s): J. DUNCAN CRONE
Keywords: Mineral exploration, Pulse EM survey, Ore deposits, Massive sulphides, Drilling, Geophysics, Boreholes.
Issue: 876
Volume: 78
Year: 1985
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Summary: Brogan coal containing mean averages of 6,93% w/w total sulphur (1.1% sulphate sulphur, 1.6% organic sulphur and 4.24% pyritic sulphur) and 16.34% mineral ash was used as the test coal in these studies.
Shake-culture leaching studies on seven size fractions of the coal, ranging in size from 0.045 mm to 1.7 mm, showed that the rate of pyrite leaching was inversely proportional to the particle size. As the use of continuous stirred tank reactors would be uneconomical for the reclamation of...
Publication: CIM Bulletin
Author(s): R.G.L McCREADY, MARCOS ZENTILLI
Keywords: Coal reclamation, Waste dumps, Bacterial leaching, Acid mine drainage.
Issue: 876
Volume: 78
Year: 1985
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