Magmatic Ore Deposits - Metals and Society: An Introduction to Economic Geology - page 62

Fig. 3.15 Sulfur isotope data

BASALTS

UNMINERALIZED
INTRUSIONS

Daldykansky

Kureyka River Intrusion

MINERALIZED - ECONOMIC
INTRUSIONS

Norilsk I Intrusion

Talnakh (NE) Intrusion

Talnakh (NW) Intrusion

02468 0 2 4 6 18 20

δ

34 S / Vienna Cañon DiabloTroilite (VCDT)

from that of normal mantle magmas. In the opinion of many geologists, this sulfur was
assimilated into the magma where it triggered the segregation of the sulfide ores.
The assimilation of sedimentary countries is believed to have taken place as
magma flowed through conduits in the sedimentary pile, as illustrated in Fig. 3.16 .
To complete the picture it must be noted that the sedimentary S is assimilated in the
form of sulfate. To convert it to sulfide requires the addition of a reductant, which,
in the case of Norilsk was either coal of the upper sedimentary unit or organic
matter in the carbonates.

3.4.5 Other Ni Sulfide Deposits

Of equivalent size to the Norilsk-Talnakh deposits are those of Sudbury in Canada.
For many decades following its discovery at the end of the nineteenth century
(see the account in Naldrett 2004 ), Sudbury was the only known major Ni deposit
and it served as a model for the exploration of other deposits. This turned out to be a
red herring because this deposit is truly unique, being the only known ore deposit