Relatively immobile elements like Zr, Nb, Ti, and heavy REE (Gd through Lu) can be very useful for identifying protolith for altered rocks.

Dear Mr. Bute,

it is no obstacle to use diagrams showing the REE normalized to PAAS or chondrite from shear zones or alteration zones. It depends on what you are intersted in and how your sampling campaign has been carried out. Random sampling for these follow-up REE investigations is not recommended. In case of such linear architectural elements I prefer samples for interpretation taken along a transect perpendicular to strike and in case of openess to depth done at different depth in hte same way. In this case I am convinced you will obtain results which change with the zonation of alteration.

I wish you much success

H.G.Dill

I would be cautious. In some cases, U-mineralization can mobilize even nominally immobile trace elements. Plots of U vs. Nb or REE, for example, might or might not show a correlation. If they don't, fine. If they do, then the mineralization has probably overprinted your host.

Dear Prof. Dill,

Actually the shear zone strikes N-S, Consist of brecciated, cataclasite and mylonitic zone, progressively from the core to the rim. The samples were obtained perpendicular to the strike. The shear zone is hosted by bt-Ms granite, and within the sheared zone there are mafic volcanic rocks sheared together with granite. sheared zone is intensely hematized especially at the rim where the volcanic rocks are.

Distinctively, the uranium is >1000ppm at the boundary between the sheared granites and the mafic volcanic rocks. so from the previous work they identify the mineralized zone as altered rhyolites, but from my data of REEs and HFSEs the samples in the mineralized zone are grouped into two different patterns, which drew my attention, suggesting they are not genetically related.So, I compared the chondrite from the fresh basalt and fresh granites from previous studies, the mafic volcanic rocks follow thesame pattern with the basalt while the altered/sheared granite follow same pattern with the granite. 

Thanks. 

Dear Prof. Beard

There is no correlation between U and Nb but there is positive correlation between U and total REEs.

Thanks