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A QUANTIFIED METHOD FOR SEPARATING THE ALTERATION ZONES IN PORPHYRY COPPER SYSTEMS (BASED ON THE FLUID INCLUSION DATA)

AUTHOR/S: O. ASGHARI, A.HEZARKHANI
Sunday 1 August 2010 by Libadmin2007

7th International Scientific Conference - SGEM2007, www.sgem.org, SGEM2007 Conference Proceedings/ ISBN: 954-918181-2, June 11-15, 2007

ABSTRACT

The Sungun porphyry copper deposit (PCD) is located in East Azarbaijan, in
the NW of Iran. The Sungun porphyries occur as stocks and dikes ranging in
composition from quartz monzodiorite through quartz monzonite. Four types
of hypogene alteration are developed at Sungun, potassic, phyllic, propylitic and
argillic. Based upon their phase content, four types of fluid inclusions are common
at Sungun (1) vapor, mono-phase (2) vapor-rich, two-phase, (3) liquid-rich twophase,
and (4) multi-phase. Halite is the principal solid phase in the latest one.
We used multiphase inclusions to calculate the point pressure and hydrothermal
fluid density. Discriminant analysis is a multivariate statistical method which
could be applied to separate the alteration zones "e.g., based on the fluid inclusions
data". Six variables have been measured and calculated for each separated sample,
including the homogenization temperature, salinity, pressure, depth, density and
the Cu grade. To find the linear combination of these variables which produces
the maximum difference between the defined alterations, we defined a function
that produced a significant difference, a critical score (R0=1.83) and mahalanobi’s
distance (RPotassic-Rphyllic=4.02) that is introduced as transition zone. By using
this function we can allocate the new fluid inclusions "with unknown origin" to one
of the two original alteration of potassic or phyllic. In other words, new samples,
not containing index minerals, could then be categorized as potassic, phyllic or
potassic-phyllic on the basis of the linear discriminant function of their variables.

Keywords: Fluid Inclusion, Porphyry copper deposit, Discriminant analysis,
Alteration.

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