Hi, Saif Abo Khashaba, here are my opinions and suggestions.

1) alteration types, like sericitization and chloritization, should be firstly identified by mineral assemblages, rather than chemical compositions, maybe you can make some thin sections and observe them through optical microscope.

2) If you have collected samples undoubtedly fresh, making comparison between your samples and relevant fresh rocks may help.

3) As our textbook described, since alterations are commonly caused by water-rock interactions, the altered granite samples are expected to contain more water, which can be reflected by their loss on ignition (LOI).

4) this is the first time for me to consider this question. Your point is quite unique and novel, and gives me new inspiration. subjectively, I suppose that trace and rare earth elements are potential to record the alteration process, since it generally involves the precipitation of new minerals. Therefore, the chemical change would depend on the mineral assemblages newly formed, differently. It is an interesting topic.

5) LILEs (Large Ion Lithophile Elements) and LREEs will decrease, while HFSEs (High Field Strength Elements) will relatively increase, I suppose.

Those are my simple thoughts, hope can help you.

GOOD LUCK!

Dear Saif M. Abo Khashaba ,

if you want to recognize the type of alteration in granitic rocks you don't need a geochemical study of trace elements and REE. With a detailed petrographic study you should be able to recognize the alteration, with the simple study of your thin sections. Sericitization it's very easy to recognize under the microscope (http://www.alexstrekeisen.it/immagini/pluto/sericite0138(3).jpg)

Give importance to PETROGRAPHY first and then complete your study if you need.

Regards,

Gabriele

I suggest that you use Pearce Element Ratios or General Element Ratios. Both work well specifically to identify and quantify alterations.

Stanley C (2017) Molar element ratio analysis of lithogeochemical data: a toolbox for use in mineral exploration and mining. In: Tschirhart V, Thomas MD (2017) Proceedings of Exploration 17: Sixth Decennial International Conference on Mineral Exploration, pp 471–494 (2017)

Stanley CR, Madeisky HE (1996) Lithogeochemical exploration for metasomatic zones associated with hydrothermal mineral deposits using molar element ratio analysis. In: Introduction, Lithogeochemical Exploration Research Project, Mineral Deposit Research Unit, University of British Columbia, Short Course Notes, 200 p

Dear Mr. Khashaba,

at the beginning of your study should be a geological-petrographic (composition, structure, texture) mapping with ground-follow-up sampling of specimens typical of the lithotype of the various zones identified in the field. It has to be extended into stream sediment sampling to decipher the proximal and distal or hidden alteration zones. For a qualitative and quantitative approach I suggest a heavy mineral analysis because the majority of relevant alteration mineral such as phosphates, topaze etc. are heavy minerals. The rest made up of feldspar and mica can be used for the quantification of albitisation, muscovitisation (in this case Rietveld XRD quatification is helpful). After having performed the geological and mineralogical "homework" you can enter the trace and rare elements , e.g., REE. What is important that you directly can assign trace element anamolies to potential host minerals, e.g. Li either in mica (zinnwaldite, lepidolite) or in phosphate (amblygonite). You can decide whether Nb and Ta prevails in columbite s.s.s. Follow-up REE investigations follow suit to the approach described above.

Never jump the line: (1) Geology, (2)mineralogy/petrography, (3) geochemistry with its subdiscipline (e..g. isotopes).

H.G.Dill

Dear Khashaba

I would also suggest the same as Dr. Dill has mentioned. This is the ideal way of collecting any evidence for your study .e.i Field study, petrography, and too for the alteration as well. This will able give much evidence and then you can further investigate the samples for geochemical composition particularly the trace elements...