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Vaibhav Singh posted an Question
October 27, 2021 • 20:00 pm 30 points
  • IIT JAM
  • Geology (GG)

Please explain this sir. ch.3,pg 40,jdw.

The sudden loss........plutonic rocks. I know that if volatile like H2O can break the Si -O bonds and ,it reduce the melting temp/crystallization temp. of silicate minerals..this I know from knowledge of flux-melting. but I can't get this lines.here.

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    Mayank vedwal Vedwal Best Answer

    Here these lines are not related with flux melting.... In flux melting the volatiles are added to the system to decrease the melting temprature of the system. But here author is talking about a condition where the H2O rich fluid phases are removing from the system due to which the crystallization temprature of system suddenly increases. Now initially the melt was crystallizing at low temprature but now it requires more heat and time to crystallize. This represents a type of bimodal crystallization process which results in porphyritic texture in rocks.

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