Hi Sadegh, in low-sulfidation epithermal veins you can date the sericite. In high-sulfidation epithermal systems you can date alunite. Cheers Daniel
Dear Sadegh: great answer that of Daniel, I would like to add that those two minerals mentioned, sericitie and alunite, are going to be found in the low temperature aureole of hydrothermal alteration surrounding the veins. Both bear potassium, and of course its radioactive isotope 40K, which decays to 40Ar and 40Ca in a well known branched decay scheme. So, you could apply the K-Ar or Ar-Ar methods for dating the aureole, and the age of the aureole would be practically the same as the veins associated with it. Moreover, radiometric ages are no longer considered as "absolute" ages, but as apparent ages, since the physical and/or chemical changes which occur to the daughter isotopes, in this case 40Ar*, which is a noble gas, affect strongly the isotopic scheme. This way most radiometric ages cannot be considered as "absolute" anymore, since they have to be interpreted according to the field, petrological, and geochemical aspects of the rocks under study. Nontheless, radiometric dating is the only way we have to put a "tag" number in millions of years to the age of a rock (as joke which I often tell to my students says that: fossil dinosaur bones don't come with a birth certificate stating "I was born 66 Ma ago"!). Any other age scale, such as biostratigraphic or paleomagnetic, must be calibrated using radiometric ages of igneous or metaigneous rocks, associated with the fossiliferous strata, or directly in the lavas showing paleomagnetic inversions, because the only give relative ages! Regards, Sebastian.
Sebastian, I am on the same line with you, radio active dating, the way to go for absolute age dating bearing in mind "the no more so absolute date comment"
Dear, if the mineralized veins have Molybdenite than you can use the Re-Os dating methode which will tell you about age of mineralisation .
Regards!
Dear Sadegh Afshar Najafi: the idea of using de Re-Os dating in molybdenite is not bad at all, but it seems that the deposit you want to date is a mesothermal one, or perhaps even epithermal, therefore is quite hard that it could contain MoS2, which is a typical hypothermal, greisen o skarn mineral, formed at quite higher temperatures than those of Pb-Zn-Cu-qtz. veins.
Regards, Sebastián.
I am very much thankful to dear authors.
The deposit I want to date is epithermal, but there are both sericite and alunite in the area.
How do it possible?
Dear Sadegh, you may use the K-Ar or Ar-Ar methods for your epithermal Pb-Zn-Cu deposit also bearing sericite and alunite minerals to determine the "aboslute" age.
Sericite is formed in low-sulfidation epithermal systems but alunite is formed in high-sulfidation epithermal systems.
In my study area both of them are created. How do it possible?
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