Ultrafabric patterns in late precambrian kolhan limestones,singhbhum district,India

The transmission electron microscope has been used to study the ultrafabric changes and crystal growth during incipient metamorphism (eometamorphism) of a shallow-water microcrystalline Kolhan limestone, Singhbhum district, Bihar. The eometamorphosed limestone is characterized by gradual increase in crystal size, abrupt changes from curvilinear boundaries to strain-induced planar triple junctions, transgranular microcracks and glide planes. The textural details like growth lines, intergranular microcracks and microporosity, and fluid inclusions commonly associated with early neomorphosed limestones have been progressively eliminated by eometamorphism.