Dear Shahrokh Rajabpour,

I am not practising my job from 21 years. I made my MsC project from volcanics (In university was strong in this field) but 2 years of lignite exploitation works, 8 years in oil explorations do not have clear imagine about your question. only one think, (may be correct) if your question is contact with volcanic media, in this case The FeS2 more important, in sedimentary condition the CuS… Do not forget that pyrite.

The detection limits for these minerals could be made in (micro perhaps under micro) condition (if you have methods for their detection,

Best regards,

Laszlo     

Hi Shahrokh

If you plan on attempting sulfide Re-Os geochronology I think I can give you some basic guidelines.

1) "What is the lowest detection limits for these sulfides?"

In general you are mostly interested in the concentration of Re in determining if a sample is feasible to date (since you need enough Re to produce a useful amount of radiogenic Os).  For properly set up clean/TIMS labs the analytical capabilities may allow for dating of sulfides with 1ppb Re (using ~400mg of sample per data point). 

2) "Which Fe- and Cu-sulfides show the best results based on Re-Os background values and DL?"

Most studies have focused on pyrite and arsenopyrite to date ore deposits and have been shown to give good ages in many types of ore deposits. Copper sulfides have not been as extensively studied for robustness.

3) Other Considerations

The most important thing I think is to have a well defined question you wish to solve. For geochronolgy how precise do you need the age to be to answer your question? For very precise ages higher than 1ppb Re would likely be required. If you are just trying to decide a 100Ma age from a 1000Ma age crude data may be enough to answer your question.

Sample prep/selection should include proper petrography and ultimately should produce pure mineral separates. Samples should ideally be of a single generation of sulfide as well as avoiding any alteration and impurities as best you can.

Hope that helps!

Danny

Dear Danny,

Thank you so much for your elaborate answer.

I gained a lot of information.

Regards,

Shahrokh

Hi dear Shahrokh

Pyrite would be better than others because it may high Mo contain. But for "Geochronological" study like Re-Os you must know approximate age of mineralization or host rock. Because Re-Os half-life is about 42 billion yaers and your host mineral (pyrite) must content a lot of Mo. This method would not answer on pyrite for after mesozoic age mineralization.