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Kamiskotia - Kam Kotia, Jameland, Canadian Jamieson, Genex

Ontario, Canada

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The Kamiskotia district contains four main past producing VHMS Cu-Zn deposits, Kam Kotia, Jameland, Canadian Jamieson and Genex. The district lies within the Abitibi greenstone belt in the Timmins region of Ontario, Canada.

These four deposits are distributed over a curvilinear NW-SE to north-south strike length of approximately 15 kms and are hosted by an Upper Archean volcanic succession. They occur within a restricted, east-facing stratigraphic interval in the upper part of the Kamiskotia Volcanic Complex, dated at from 2701.1 ± 1.4 to 2698.6 ± 1.3 Ma, while the lower part of the Kamiskotia Volcanic Complex has returned an age of 2703.1 ± 1.2 Ma from, indicating that the complex is likely part of the Blake River assemblage (2701 to 2697 Ma. The Kamiskotia Volcanic Complex consists largely of felsic and mafic lava flows, with VMS mineralisation appearing to have generally developed at or near the sea floor close to inferred synvolcanic faults.

The four VHMS deposits have a number of characteristics in common, namely: i). they comprise numerous small lenses of massive sulphide; ii). they occur in a restricted (<150 m) stratigraphic interval that can be broadly correlated between the individual deposits; iii). their host rocks are predominantly mafic volcanic rocks with lesser felsic lithologies; iv). they are characterised by alteration zones comprising proximal chloritisation and silicification with more widespread semi-conformable sericitic ± chloritic zones; and v). the ore is largely composed of pyrite, pyrrhotite, chalcopyrite and sphalerite, with minor magnetite and/or galena.

Kam Kotia

The Kam Kotia mine was mainly operated between 1961 and 1972, with ore being recovered from seven (six Cu-rich, one Zn-rich) steeply dipping and shallowly (30°) northwest-plunging lenses of massive sulphide lenses. The mineralisation was hosted by a , northeast younging, steeply northeast dipping succession of mafic and felsic lavas and volcaniclastic rocks, chemical metasedimentary rocks and mafic intrusions. Those lenses occurring lower in the stratigraphic pile comprised massive sulphides, while stringer-type mineralisation was characteristic the uppermost lenses.

The lower part of the host succession comprises >155 m of variably amygdaloidal basaltic pillow lava and associated interpillow hyaloclastite. These are overlain by a 60 to 80 m thick succession of thin to very thick bedded rhyolitic tuff breccia, lapilli tuff, and tuff, which can be traced for at least 500 m along strike, with a locally sulphide-bearing chert horizon up to 2 m thick is found at the base of the interval. These felsic volcaniclastic strata occur approximately 100 m into the footwall of the Kam Kotia orebodies. A second, up to 95 m thick, interval of amygdaloidal basaltic pillow lava and hyaloclastite is exposed around 100 m west-southwest of the Kam Kotia open pit and can be traced along surface for at least 400 m to the west of the open pit.

Matrix-supported pillow breccia with a chlorite-rich recrystallised hyaloclastite matrix is found approximately 50 m to the west of the open pit, typically stained brownish red after oxidised sulphide minerals. These rocks hosted the western, non-outcropping lenses of the Kam Kotia orebody. The immediate footwall and host rocks to the main Kam Kotia massive sulphide lens are a coherent high silica rhyolite and associated breccia and tuff. These footwall rocks are composed of a lower 4 to 25 m interval of spherulitic rhyolite and associated breccia and tuff breccia, commonly strongly sericite altered and locally replaced by pyrite-rich massive sulphide. This is overlain by 8 to 16 m of locally flow-banded, sparsely quartz-phyric, sparsely to moderately amygdaloidal coherent spherulitic rhyolite which can be traced from 50 m northwest to 350 m southeast of the open pit. Overlying this in turn, is a second, 8 to 25 m thick interval of coherent spherulitic rhyolite with localised chlorite and quartz-altered autoclastic and hyaloclastite breccias and tuff breccias, which is locally cut by several generations of quartz sulphide veins and significantly to totally replaced in the southeastern wall of the open pit by up to several metres of semi-massive to massive pyrite, with minor sphalerite and chalcopyrite. An uppermost interval consists of 8 to 33 m of sparsely quartz-phyric, locally flowbanded, spherulitic rhyolite.

The immediate hanging wall of the main Kam Kotia orebody comprises two lenses of massive mafic lapilli tuff, with maximum thicknesses of 11 and 16 m, separated by a basaltic sill. An amygdaloidal pillow basalt unit up to 25 m thick is exposed approximately 65 m into the hanging wall, overlain by high K, high silica rhyolite which comprises feldspar- and quartz- phyric felsic tuff and lapilli tuff, which form the uppermost stratigraphic unit mapped in the mine area.

Three distinct types of intrusion occur in the Kam Kotia mine area. Fine- to medium-grained doleritic to gabbroic sills are found in the immediate footwall and hanging wall to the largest orebody. The footwall sill is an up to 90 m thick tholeiitic basalt which can be traced along strike for at least 450 m. A hanging-wall sill up to 65 m thick is lithologically similar to the footwall sill. Fine-grained pyroxenite dykes up to several metres across are locally present in outcrops rimming the Kam Kotia open pit, and appear to have cut the massive sulphide mineralisation.

Hydrothermal alteration Kam Kotia mine area is variable and affects all rock types. Chlorite, sericite, and, locally, quartz are the major alteration minerals, while epidote, zoisite and/or clinozoisite, iron carbonate, and fine grained biotite or stilpnomelane are only found in minor amounts. Chlorite with local silicification is most prominent in the mafic and felsic footwall volcanic strata within approximately 150 m of the northeast-trending faults to the southwest of the open pit and in the mafic volcanic and volcaniclastic rocks that make up the north wall of the open pit. Intense sericitisation affects both coherent and volcaniclastic felsic rocks east of the zone of chlorite alteration in the immediate footwall to the main orebody. Less intense sericite alteration occurs in the felsic strata up-section from the deposit.

Jameland

The Jameland mine is located 1.2 km southeast of, and along strike from Kam Kotia. Minor ore was produced from this deposit between 1966 and 1972. Host rocks to the mineralisation included chloritised and brecciated mafic volcanic rocks and felsic tuffs. The central and eastern part of the deposit comprised of up to ten 30 35° southeast-plunging, irregularly shaped lenses, whereas the western part consisted of a single 15 m thick lens. Metal distribution in the deposit was similar to that at the Kam Kotia mine, with the lower lenses being composed of massive, zinc-rich sulphides, and the upper lenses consisting largely of stringer-type, copper-rich ore.

Canadian Jamieson

Production from this deposit was between 1966 and 1971, with ore being recovered from underground mining of three stratabound sulphide lenses (the south, central, and north ore zones). Economic mineralisation occurred over a stratigraphic interval of approximately 100 m, primarily within mafic lapilli tuffs and tuff breccias, as well as interbedded rhyolite tuffs and chert and rhyolitic lava flows and associated flow breccias.

A basaltic lava unit up to 140 m thick composed of pillows up to 3 m across surrounded by strongly chloritic interpillow hyaloclastite zones occurs at the base of the east-northeast-younging host succession. This is overlain by an up to 6.5 m thick interval of laminated to thinly bedded felsic tuffs, followed across a sharp contact by a massive basalt lava flow or sill up to 22 m thick. A second interval of basaltic pillow basalt and associated hyaloclastite up to 60 m thick occurs immediately upsection from the massive basalt. Overlying the pillowed flows is a succession of interbedded felsic tuff and sulphide bearing, laminated cherty exhalite up to 25 m thick. This is in turn locally overlain by massive mafic lapilli tuff containing angular chert lapilli and amygdaloidal basalt lapilli.

Coherent spherulitic rhyolite and associated autoclastic and hyaloclastite breccia overlie the interbedded exhalites and felsic tuffs, as well as the mafic lapilli tuff. These rocks appear to have formed the immediate footwall and host rocks to VMS mineralisation at the mine. The lower 13 m of this felsic succession consists of autoclastic rhyolite breccia, overlain by up to 65 m of weakly flow-banded, locally spherulitic, sparsely quartz-phyric coherent rhyolite, which grades upsection into a second horizon of autoclastic and hyaloclastite rhyolite breccia up to 25 m thick. There is a sharp contact between the upper rhyolite breccias and an overlying succession of bedded felsic tuffs up to 20 m thick. A strongly chlorite- and/or carbonate-altered, matrix-supported, massive mafic lapilli tuff and/or tuff breccia containing up to 15% sparsely to moderately amygdaloidal basalt clasts immediately overlies the felsic tuffs. This unit, which is up to 40 m thick, also contains up to 12 vol percent lens-shaped clasts up to 15 cm across consisting of dark gray quartz and semimassive pyrite.

A third horizon of sparsely amygdaloidal pillow basalt and associated hyaloclastite overlies the mafic tuffs and tuff breccias and is up to 70 m thick. The basalts are overlain by at least 80 m of massive felsic tuff, which forms the uppermost unit mapped in the area. Fine to medium-grained, north-northwest-trending Archean dolerite dykes cut the central and eastern parts of the Canadian Jamieson area.

Hydrothermal alteration in the deposit area varies with both stratigraphic position and lithology. Rocks close to the mineralisation are generally chloritised and/or sericitised, although carbonate alteration, silicification and epidotisation also found locally. Mafic coherent and volcaniclastic rocks, as well as the synvolcanic dolerite dykes, generally exhibit patchy to pervasive chlorite alteration and are locally patchily silicified. Chlorite is associated with iron carbonate in the footwall, and dolomite or calcite occurs in the hanging wall rocks).

Genex

The Genex mine comprised two main orebodies (the C and H zones) from which 242 t of copper concentrate were produced between 1964 and 1966. The lower part of the host succession consists of up to 590 m of felsic tuff breccia, lapilli tuff, and tuff with minor felsic lava and and associated flow breccia. The H zone mineralisation is found near the top of this unit adjacent to synvolcanic intermediate dykes. The felsic volcaniclastic rocks are overlain by a 130 m thick massive basalt unit, and overlying this is a 200 m thick interval of pillow basalt and associated pillow breccia and hyaloclastite. The C zone mineralisation is hosted by an 8 m thick pillow breccia immediately overlying the pillow basalts. The hanging wall to the C zone comprises a 52 m thick massive basalt flow that is overlain in turn by a 35 m thick interval of felsic lapilli tuff and tuff. The felsic volcaniclastic strata are followed by a second basaltic flow unit, with a massive, 70 m thick basal portion and an upper, 360 m thick pillowed interval. These lavas are followed by 370 m of volcaniclastic deposits, epiclastic strata and minor mafic and felsic lavas. This succession has been intruded by numerous synvolcanic intermediate and mafic sills and dykes. There is no well-defined zonation of alteration mineral assemblages in the Genex area. Felsic rocks are largely sericitised, with alteration more intense in footwall than hanging-wall. Mafic extrusive rocks, as well as the intermediate and mafic synvolcanic intrusions, are largely chloritised, with volcaniclastic facies generally more intensely altered than coherent units, suggesting localisation of alteration-associated hydrothermal fluids in more permeable facies.

The most recent source geological information used to prepare this summary was dated: 2008.    
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.


  References & Additional Information
   Selected References:
Finamore S M, Gibson H L and Thurston P C,  2008 - Archean Synvolcanic Intrusions and Volcanogenic Massive Sulfide at the Genex Mine, Kamiskotia Area, Timmins, Ontario: in    Econ. Geol.   v103 pp 1203-1218
Hathway B, Hudak G and Hamilton M A,  2008 - Geologic Setting of Volcanic-Associated Massive Sulfide Deposits in the Kamiskotia Area, Abitibi Subprovince, Canada: in    Econ. Geol.   v103 pp 1185-1202


Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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