Hi,

do you have island arc setting, ocean island or MORB? I think there are several good papers and books on this question, to read trough, but if you have zircon in basalt, it should of different origin, and you can make sure by morphological observations. Zirconium is the element, and you may also have it as substitution in several minerals, or as baddeleyite...

Regards,

 F.

Thanks F, It is more of an Ocean Island setting. There are no individual zircons in the basalt, but an unusual concentration of zirconium where it has increased progressively and tends to be more in the most evolved magmatic phase.

I would expect that your suite of rocks is (close to) silica-undersaturated, with high alkali content. This stops zircon from forming, and, as long as you also do not have amphibole forming, zirconium can increase during fractional crystallisation (if that's the process operating to give you the increse in SiO2 - partial melting will do the trick as well, of course). The differentiated  silica-undersaturated rocks of the East African Rift show very high Zr contents, for instance.

Dear Mr. Lar,

I would deny your question. See e.g. the paper Siebel, W., Schmitt, A.K., Danišík, M., Chen, F., Meier, S., Weiß, S., Eroglu, S., 2009. Prolonged

mantle residence of zircon xenocrysts from the western Eger rift. Nature

Geoscience 2, 886–890.

You can even use the zircon X moprhology to pin-point the derivation where the XX came from. There are also some studies about the basalt-hosted sapphire deposits in SE Asia which often are accompanied by zircon (gemstone) deposits as well (e.g. Cambodia).

Further literature you may find also in e.g., Dill, H.G., Weber, B. and Klosa, D. (2012) Crystal morphology and mineral chemistry of monazite–zircon mineral assemblages in continental placer deposits (SE Germany): Ore guide and provenance marker.- Journal of Geochemical Exploration, 112: 322-346.

Kind regards H.G.Dill

Many thanks for the exposure to literature.