Look at Steve Haggerty' s distribution of fO2 in the 91 oxide volume of RIM.

Thanks for the answer Dr Xirouchakis. Unfortunately, have no access on that.

I am out of the country and thus cannot access my books. I'll get you a copy when I return. Apologies.

Thanks in advance. Appreciate that.

May be my friend and colleague -Aleksey Goncharov be help to you.

Ok, thanks a lot Dr Berezin.Will try to contact him.

Yours,

Ioannis

You may find that the oxidation state of the Continental Crust varies by orders of magnitudes over distances of a few kilometers. This has been documented in the Adirondack Mountain terrane, for example. Given such variability, I wonder if it is possible to generalize about changes in ƒO2 relative to depth.

Thanks Dr Lamb,

But, as a general, can we infer that fO2 decreases with depth?

In terms of an ƒO2 increase or decrease I assume you mean relative to some buffer (e.g., QMF). In this case I'm not sure that, given the variation, once could discern a trend for continental crust (unlike the mantle). I suspect that ƒO2 will vary with both T (depth) and with bulk composition. So, for a given rock type (e.g., mafic, pelitic, quartzofeldspathic, etc.) one might be able to discern a general trend, but for the crust in general it may be difficult. However, I hasten to add that I have never seen a compilation of ƒO2 estimates for the crustal rocks for rocks that span the entire range of metamorphic conditions; from the lowest to the highest grades of metamorphism. If you find such a compilation please let me know.

Dear Baziotis, also try to read this article:

http://link.springer.com/article/10.1007/s12583-014-0402-1

Really thanks. Will go through this article and then let you know.

Yours,

Ioannis

Metasomatism plays an important rolle in the oxidation state. The existance of amhibole (kaersutite) or phlogopite in the lower crustal rocks can increase the oxidation state. See Nasir, S. and Rawas A. Am. Mineral. 2006 91, 1163-1193, Nasir et al., 1992. Tectonophysics 213:359-366 , Nasir, 1996, Eur. J. Mineral. 8:153-163