Shivam Sharma posted an Question
September 03, 2020 • 15:11 pm 30 points
  • CSIR NET
  • Earth Sciences

Given below is a thin section sketch (not to scale) of a banded metamorphie rock of normal pelite bulk rock conposition. the rock shows developrment of differen

Not able to predict facies of metamorphism. High Pressure Polymorph is Kyanite. And Low tempreture polymorph is Andalusite. And Low P and Low T is ?

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    Rahul kumar best-answer

    1. (i) Given that the protolith is normal pelite Kfs+Qtz+Grt+Sill+Bt+Plg (Band A) is Granulite facies Mu+Bt+Qtz+Grt+Chl+Plg (Band B) belongs to Amphibolite facies Look at the attached figure for metamorphic mineral assemblages (ii) Possible tectonic discontinuity is a fault; look at the offset of chlorite band (Chl) in diagram 2. High P, Low T polymorph of Al2SiO5 is Kyanite Low P, Low T polymorph of Al2SiO5 is Andalusite High P, High T polymorph of Al2SiO5 is Sillimanite Refer to the attached figure

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    Sajan sarthak Best Answer

    A is upper amphibolite B is greenschist facies. PQRS IS A DEFORMATION SURFACE. KYANITE IS HIGH P low T Sillimanite Low P and High T

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    But in question Low P and Low T is asked so it is andalusite

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    yes Shivam you are absolutely right

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