Anukruti posted an MCQ
August 30, 2020 • 20:05 pm 30 points
  • IIT JAM
  • Geology (GG)

Calcic plagioclase under hydrothermal alteration may produce

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    Sajan sarthak

    Uralitization is the process of deuteric alteration of pyroxene (most commonly augite) to form amphibole (actinolite-tremolite). The alteration occurs during either late-stages of magmatic crystallization at low temperatures (< 500 °C) or during low-grade metamorphic events (sub-greenschist facies metamorphism).

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    Sajan sarthak Best Answer

    Lower temperature (150–350°C) hydrothermal alteration of plagioclase typically leads to feldspar turbidity, particularly in calcic plagioclase, and widespread formation of secondary minerals such as calcite, sericite, epidote and chlorite. sericite is White mica so answer should be sassurisation.

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    Rahul kumar best-answer

    Sassuritization is a hydrothermal alteration process by which calcium-bearing plagioclase feldspar is altered to a characteristic assemblage of minerals called saussurite (typical assemblage formed includes zoisite, chlorite, amphibole, and carbonates).

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