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Part 4: Uncommon Magmatic Structures in Granites of the Borborema Province

Roberto Weinberg, Monash University, Australia

 

 

 

Magmatic Structures Continued

  • Feldspar Deformation: Magmatic and Solid-State
  • Dendritic Feldspar

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    Magmatic and Subsolidus Feldspar Deformation

    Some beautiful megacryst deformation in Itaporanga and Pedra Mijada plutons. In Itaporanga many megacrysts are bent as in (A) suggesting squeezing of interstitial magmas and megacryst deformation

    A) Squeezed and bent cumulate K-feldspar. Is this magmatic?

     

    bent K-feldspar phenocryst

     

    B) Tail in K-feldpar megacryst (5 cm long), accompanied by other grains with no tails.

    tail in K-feldspar phenocryst, recrystallization

     

    C) Solid-state zoned K-feldspar from Pedra Mijada Pluton for comparison

    zoned K-feldspar phenocryst, deformed

     

     

    Dendritic K-feldspar in Boqueirao pluton

    dendritic K-feldspar

     

     

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