Dear Dr. Lv:

 it is often much better to do not investigate the same effect by different laboratories but try and find different methods to either sustantiate the results of an analysis, in this case REE, or discard a theory on the origin of a mineral. In this case I point to two independent methods. Why not making use of fluid inclusions and considering the morphology of zircon grains which is within a certain interval of temperature strongly correlated to T changes? You can find such morphological studies in my list of publications available on the Researchgate Server.

I wish you much success

H.G.Dill

Dear Dr. Lv: could you please load a representative spider profile of your hydrothermal zircon? Thanks.

Hi Dr Lv:

Negative anomalies of Ce in zircon from pegmatites may reflect the nature of granitic melts that may have been derived from partial melting of sedimentary rocks. However, zircon in pegmatites associated with I-type granites do not show such negative Ce anomalies in the pegamatites related to S-type granites.

I hope a compilation of a large dataset on this issue would provide a clearer picture.

Regard,

Yang, Xue-Ming

Hi Dr Lv,

I don't know if this could be helpful to you, but take a look into those papers:

Möller, P., Bau, P., 1993. Rare-earth patterns with positive cerium

anomaly in alkaline waters from Lake Van, Turkey. Earth Planet.

Sci. Lett. 117, 671– 676.

Smythe, D. J., & Brenan, J. M. (2016). Magmatic oxygen fugacity estimated using zircon-melt partitioning of cerium. Earth and Planetary Science Letters, 453, 260-266.

Ballard, J.R., Palin, M.J., Campbell, I.H., 2002. Relative oxidation states of magmas inferred from Ce(IV)/Ce(III) in zircon: application to porphyry copper deposits of northern Chile. Contrib. Mineral. Petrol. 144, 347–364.

otherwise, I think it has something to do with the high fluid oxygen fugacities?!!

Good luck to you;

cheers,

Oussama ZEMRI,

I believe that your explanation is sustainable. Nevertheless, the variability could be in response to different degrees of fluid/rock alteration, which should be taken in condiderstion. For some reason the interacting fluid has undergone high oxygen fugacity.

Hope sounds reasonable.

Regards. 

dear all;

How to found PVTX for three phases fluid inclusions that homogenize by halite dedisappearance. 

Do your halite daughter crystals homogenize prior to or after bubble dissappearance?

The halite daughter crystals homogenize after bubble dissappearance 

please see attachment 

De: "Raúl Lira"

Fecha: 30 jul. 2017 00:13

Asunto: 1994%2c Bodnar&Vityk_300dpi.pdf

Para: "Raúl Lira"

Cc: 

De: "Raúl Lira"

Fecha: 30 jul. 2017 00:13

Asunto: 1994%2c Bodnar&Vityk_300dpi.pdf

Para: "Raúl Lira"

Cc: 

 Find attached a paper ftom Bodnar and Vitik that will help you calculate salinity. Regards.  Raúl.

Sorry Dr. Lv: the previous comment was addressed to another colleague. Regards.

Dear Dr. Lv,

I just wanted to ask. Are there any other REE minerals present in the pegmatite? Phases like monazite or even apatite could concentrate Ce before the actual zircon crystallization. 

Marek Dosbaba

Firstly, I would appreciate all scholars which pay  attentions to my question.

For the advice from Prof. Dill, I am actually trying to do that.  

For the advice from Dosbaba, I can definitely tell you that there are some REE-bearing minerals, such as garnet, apatite, monazite, co-exist with zircon in pegmatite. But I do not consider their prior crystallizations induce the negative Ce anomaly  in zircon. Because  the  crystallization of REE-bearing minerals will simultaneously affect all REEs due to their similar radius and charge, as proved by experiment (Trail, 2012). In nature, the intergrowth of zircon and other REE-bearing minerals is commonly observed in granites, but no zircon with negative Ce anomaly has been found so far.

For Jorge C. de Moura, thanks for your comments and advises again. I agree with your opinion that zircon is hard to be melted, but the studied zircons have been formed under a hydrothermal condition. They are easily to be altered by fluids after metamict due to high abundances of U and Th, as proved by Geisler et al. (2003). In most cases, the altered zircons have evident enrichment of LREE (e.g., Hoskin, 2005). I am sure that the zircons represented by red lines have been suffered from metamict, because it is easily to be identified by CL or Raman. With regards to  their earlier crystallization than pegmatite formation,  it is denyed by their younger ages than zircons from rim zone of the same pegmatite, and their Hf isotopes, morphology, paragenetic mineral association, inclusions suppot thay are formed at   pegmatitic conditions. They are also distinct to the xenolith zircons observed in pegmatites. The latter is characterized by oscillatory zoning, older ages and typical REE patterns.

Waitting and expecting for more advices!

Dear  Jorge C. de Moura,

Thanks for your advices again. What I reply to you last time is only based on your fist comments.

I actually know that the Ce anomaly of zircon is mainly controlled by oxygen fugacity, and Eu anomaly is controlled by both  oxygen fugacity and crystallization of plagioclase. I have also consider the mechanism responcible for the nenative Ce anomaly relates to the variation of oxygen fugacity. The zircons from lunar rocks and meteorolites commonly show no anomaly or slight negative anomaly (Ireland and Wlotzka, 1992; Snyder et al., 1993), which means a reducing condition contributes to weakening the positive Ce anomaly in zircon. However, the comparison of the negative anomaly of zircon from quartz core to those of zircon from  extraterrestrial rocks seems don't  support the former induced by a reducing condition due to its more intense negative anomaly. What we need to know is the partition coefficient of Ce between zircons and fluids under a  reducing condition, but very few papers can be referred.

It is indeed intriguing, because Ce and Eu give contrasting indications about the oxigen fugacity. On the other hand, there is no other reason than oxidation state for fractionation of either Eu or Ce with respect to their neighbours. Whatever the mechanism involved, the most reasonable inference is that the two depletion episodes did not occur during the same process, one of them being inherited. So if you come up with a good answered I'd be also interested.

Perhaps an intense post-crystallization effect (an interplay of pervasive hydrothermal alteration and some other disturbance) changed the established norm. I am baffled and have interest to know the correct explanation for this observation. The higher valence ions in the multivalence Ce that preferentially make them readily partition into zircon will ordinarily not make this happen.

Dear sir,

I think the Oxygen fugacity of the melt is not the only parameter here. Under reducing conditions (relatively), the nature(composition) of the late hydrothermal fluid phase will define the behaviour of the Ce relative to the other REEs. It may also be a separation event between the later and earlier phases of the magma, causing the selective decoupling of Ce3+ itself into the Magma, aided by later alteration/phase transition from the rising liquid. Like the CO2 content in the fluid phase controls the behaviour of Rb and Nd, similarly the slight change in fO2 coupled with the change in composition may also cause the relative depletion in Ce3+ state itself.