I agree with Leonid. There is no exact way to distinguish magmatic and hydrothermal zircon. Electron microscopy is a really strong way to distinguish different crystallography domains of the zircon - utilising SE, BSE and CL imaging, where magmatic-derived zircons will typically display oscillatory-zoning. Hydrothermally derived zircons will have less defined features, where you can perhaps see homogenisation, resorption or mixing of domains as well as fracturing. Trace elements could be a good indicator, for example perhaps lower Th concentrations could reflect the preferential partitioning of Th into hydrothermally-dervied monazite as they have grown coevally, yet this would require a working knowledge of the rock mineralogy and petrogenesis. Inclusions within zircons could be key as well e.g. xenotime, monazite, and apatite, but nothing empirical on zircons alone. 

Saleh

Dear Saleh Ibrahim Bute,

I actually practising my job like a hobbi… For these I reached my strongest level in petroleum exploration even if was interested in magmatic dominium… For these I have found these two articles which can help you…

 http://www.geology.wisc.edu/~wiscsims/pdfs/Fu_ChemGeol_2009.pdf

 http://www.minsocam.org/ammin/AM74/AM74_865.pdf

You have to be sure one thing if exists zircon formed in magmatic condition and hidrotermal condition, you are able to separate them… Try to study zircons of granite ( I-granite) and sure hidrotermal condition formed zircons …

http://www.gly.uga.edu/railsback/Fundamentals/BowensRxnSeriesSketch07LS.pdf

 And take in consideration the material inclusions… They will tell lot about the Zircon condition formation.

Best Regards,

Laszlo  

Ibrahim Bute,

Dear Saleh: all the previous are good answers, I only can add the following: one distinguishing feature of magmatic zircons which is seen very frequently is their fine oscillatory zoning, a texture not observed in metamorphic or metasomatic zircons, for obvious reasons. Regards, Sebastian.

I agree with the answers above, but would add that context can tell you a lot. If the zircon is intergrown with hydrothermal ore and gangue minerals that would favor its interpretation as hydrothermal zircon, but if the zircon occurs in relatively unaltered igneous rock, that would favor its interpretation as igneous zircon.

It is complicated. Your question has several parts that revolve around the textures and composition of:  a) magmatic zircon; b) hydrothermally altered zircon; and c) hydrothermal zircon.  The literature on textures on magmatic zircon is considerable, and as pointed out, oscillatory zoning is one way used to distinguish growth in magma. Hydrothermally altered zircons are common, and they can be distinguished by some alteration textures (esp in BSE and CL) that are related to element redistribution, especially Ca, F, and Al along cracks and zones.  In the case of hydrothermal alteration, radiation damage matters because damaged zircon is more easily altered by fluids.  True hydrothermal zircons are not common, certainly not in the literature, but see Schaltegger, U., 2007. Hydrothermal zircon. Elements, 3(1), pp. 51-79.  Zoning in this last group reflects changing fluid composition, so they can have textures similar to igneous zircons. Finally, note that there are many papers on metamorphic zircons or zircons affected by metamorphism: new zircons can grow, or old zircons can be overprinted with new textures that reflect altered composition (see Hoskin and Black, 2000, J. Metamorphic Petrology). Good luck. 

Dear Saleh, I agree with what was mentioned before. I'm not sure about the reason for your question, but in my opinion and experience and if you are looking at thin sections of hydrothermally altered rocks try to understand the textures and the occurrence of these zircons. I would say that if it is hydrothermal I should grow up with other hydrothermal phases (e.g. chlorite, micas, epidote), along with some kind of alteration paths that you must be able to follow, instead, magmatic zircon should grow up randomly in your rock. 

Check also this paper

http://www.sciencedirect.com/science/article/pii/S0169136813001388

Cheers.

dear saleh

you have many ways to figure out :

1- from geochemical environment study (area)

2- from textures under thin section

3- from the accessories minerals.

best regards