Dear Mr. Masoud,

There are three models for formation of porphyry deposits:

1. Porphyry Cu-type deposit , 2. Porphyry Mo-type deposit and 3. porphyry W-type deposits.

In case of porphyry copper deposits as example are associated with arc-related “calc–alkaline” or I-type oxidized magmas generated adjacent to Andean type subduction zones.

This body of oxidized magma has relatively low initial H2O content and will rise to high levels in the crust before significant crystallization takes place.

It is likely that some melt fractions from this high level magma chamber will be tapped off and extrude on the surface. These fractions will crystallize to form volcanic and subvolcanic (porphyry) suites of rocks whose compositions will not be highly differentiated (i.e. granodioritic or rhyodacitic) because of the low degree of fractionation that has taken place prior to extrusion.

This sub-volcanic magma fraction is emplaced at low load pressures the saturation water content will be relatively low and probably not significantly different from the initial water content.

By decreasing in pressure of the system Vapor-saturation will occur early in

the crystallization sequence.

Copper in this evolved system is a compatible element in a crystallizing granitic melt so copper will partition or retain into accessory sulfide phases and biotite where DCucrystal/melt > 1.

The low rate of crystallization of the system means that very little of the metal

will have been removed from the melt by the time water-saturation occurs. The vapor phase here is characterized by high Cl− concentrations and it will efficiently scavenge and recover Cu from the silicate melt as metal-complex form.

In this setting a high level granodioritic I-type magma will exsolve an aqueous fluid phase that is highly enriched in Cu and form a typical porphyry copper deposit.

Consequently sulfur in this case is useless.

Reference: Introduction to ore-forming processes (L. Robb - 2005).

Best regards.

Dear Masoud.

I am sending you these papers i hope you can get good answer from these papers.

Remarked