IOCG and Porphyry-Cu deposits in Northern Finland ... - IAGS 2011
IOCG and Porphyry-Cu deposits in Northern Finland ... - IAGS 2011
IOCG and Porphyry-Cu deposits in Northern Finland ... - IAGS 2011
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<strong>IOCG</strong> <strong>and</strong> <strong>Porphyry</strong>-<strong>Cu</strong> <strong>deposits</strong> <strong>in</strong><br />
<strong>Northern</strong> F<strong>in</strong>l<strong>and</strong> <strong>and</strong> Sweden<br />
Tero Niiranen<br />
Geological Survey of F<strong>in</strong>l<strong>and</strong>, P.O. Box 77, 96101 Rovaniemi, F<strong>in</strong>l<strong>and</strong>, e-mail<br />
tero.niiranen(at)gtk.fi<br />
Abstract<br />
The field excursion visits the iron <strong>and</strong> iron-copper-gold <strong>deposits</strong> <strong>in</strong> Kolari-Pajala<br />
area currently under development by Northl<strong>and</strong> Resources S.A. <strong>and</strong> the Aitik <strong>Cu</strong>-<br />
Ag-Au m<strong>in</strong>e <strong>in</strong> Gällivare operated by New Boliden Ab.<br />
At Kolari we will visit the Hannuka<strong>in</strong>en Fe-<strong>Cu</strong>-Au deposit which was operated<br />
by Rautaruukki Oyj <strong>and</strong> subsequently by Outokumpu Oyj between 1981 <strong>and</strong><br />
1990 total production be<strong>in</strong>g about 4.5 Mt @ 43% Fe, 0.48% <strong>Cu</strong>, <strong>and</strong> 0.29 g/t Au.<br />
Northl<strong>and</strong> Resources has been develop<strong>in</strong>g the Hannuka<strong>in</strong>en deposit s<strong>in</strong>ce 2005 <strong>and</strong><br />
the current resource estimate for the Hannuka<strong>in</strong>en is 110 Mt @ 33.9% Fe <strong>and</strong> 0.17%<br />
<strong>Cu</strong> (measured + <strong>in</strong>dicated, 15% Fe, cut off) with additional 88 Mt <strong>in</strong>ferred resources.<br />
The Hannuka<strong>in</strong>en deposit is controlled by a thrust zone which is part of the crustalscale<br />
Kolari-Pajala shear zone system. The ore is hosted by altered varieties of 1.86<br />
Ga diorite <strong>in</strong>trusion <strong>and</strong> 2.2-2.05 Ga mafic volcanic rocks. The deposit has been suggested<br />
to belong to <strong>IOCG</strong> class.<br />
At Pajala the excursion visits two iron <strong>deposits</strong>, the Sahavaara <strong>and</strong> Tapuli.<br />
Both <strong>deposits</strong> are skarn-hosted magnetite <strong>deposits</strong>. The resource estimate for the Tapuli<br />
is 101 Mt @ 26.9% Fe (measured & <strong>in</strong>dicated). For the Sahavaara, the current<br />
resource estimate is 64.9 Mt @ 42.5% Fe (measured & <strong>in</strong>dicated) with additional<br />
34.7 Mt <strong>in</strong> <strong>in</strong>ferred category. Both the Tapuli <strong>and</strong> Sahavaara <strong>deposits</strong> are hosted<br />
by 2.4-1.98 Ga sedimentary sequence of dolomitic marbles, phyllites, <strong>and</strong> graphitic<br />
schists.<br />
At Gällivare, we will visit the Aitik <strong>Cu</strong>-Ag-Au m<strong>in</strong>e which is one of Europe’s<br />
largest copper producers. M<strong>in</strong><strong>in</strong>g at Aitik started at 1968 <strong>and</strong> s<strong>in</strong>ce then about<br />
500 Mt of ore has been m<strong>in</strong>ed from a open pit operation. The total ore reserves <strong>in</strong><br />
2009 were 747 Mt grad<strong>in</strong>g 0.25% <strong>Cu</strong>, 1.7 g/t Ag, <strong>and</strong> 0.14 g/t Au. In 2010 the ore<br />
production was 27.6 Mt. The Aitik deposit is hosted by gneissic varieties of regionally<br />
wide spread calc-alkal<strong>in</strong>e Hapar<strong>and</strong>a Suite <strong>in</strong>trusives <strong>and</strong> co-magmatic volcanic<br />
rocks. The geological features for the Aitik deposit suggest that it is a metamorphosed<br />
porphyry-copper deposit.
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