Dear Dr. Zhang,

there is a mineralogical way making use of the zircon grain morphology and a chemical way making use of the trace element composition of zircon. The pertinent literature is cited below:

Belousova, E.A., Griffin, W.L., O’Reilly, S.Y., and Fisher, N.I., 2002. Igneous zircon: trace element composition as an indicator of source rock type: Contributions to Mineralogy and Petrology 143, 602-622.

Pupin J.P. ,1980. Zircon and granite petrology. Contribution Mineralogy Petrology 73, 207-220.

I wish you much success

H.G.Dill

Xenocryst is a term used to describe foreign crystals within an igneous rock. These are effectively monomineralic xenoliths incorporated into the magma from country rocks

Magmatic material when passes through crust take xenocryst of other rocks which incorporate the zircon which can be said as inherited zircon.

so the terms... inherited zircon and  zircon xenocryst denotes the same meaning.

Dear Dr. Zhang,

Zircon xenocryst refers to zircon that was originated from a complete different source of that of the magma, most likely entrained into the magma during assimilation of the wall rock. However, inherited zircon is more ambiguous since you can have inherited zircon incompletely reabsorb from the source that melted and generated your magma. New terminology it is being apply to avoid this confusion, for example zircon autocryst, antecryst and xenocryst. Find attached a paper where this is explained in detail and may help to respond your questin. 

Dear Prof. Dill,

Thanks a lot for your answer. Pupin and Belousova's papers mainly focus on the zircon grain morphology and trace elements fingerprints. They did not mention how to distinguish inherited zircons and zircon xenocrysts.

Best regards, Rongqing

Dear Asoori,

Thanks a lot for your reply. Yes, I just want to classify the zircons or zircon cores with old ages > the emplacement age of the low-T S- or I-type granites and need to know which grains are inherited from the source.

Kind regards, Rongqing

Dear Alejandro,

Thank you very much. I will read this nice paper carefully.

Cheers, Rongqing

Zongqing,

               Simply, inherited zircons are xenocrysts, it is not unusual for inherited (xenocrystic) grains to develop rims in the crystallising magma. The inherited zircons, and zircon cores will be older and may have a different trace element composition, as described in the Belousova paper, from the crystallising zircons. U/Pb isotope ages are the main way of determining if a zircon is inherited or not.

If you are defining a xenocryst as a zircon assimilated from rocks other than from the anatectic source, for example, zircon assimilated from the rocks the magma is intruding, then once again using the U/Pb age and trace element data is the way.

Hafnium and oxygen isotopes may also be useful in discriminating between zircon types?

Regards,

Steve Craven

Prof. Zhang,

I suggest that you may try to make a comparison of age, isotope and spectroscopic feature between those zircon cores and zircon from wall-rock of granite. If thay have the same features, the former is more possible to be zircon xenocryst; If not, the former is more possible to be inherited zircon from granite source located deeply in crust.

Wish it helpful for you!

Dear Prof Zhang, could you find a satisfactory answer to your query about differentiating between zircon autocryst and xenocrysts in an S type granite?