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Characteristics of Mesoproterozoic Felsic Meta-Volcanics from the Shillong Group of Rocks, Meghalaya, North East India


Affiliations
1 Geological Survey of India, North Eastern Region, Shillong 793 003, India
2 Department of Applied Geology, Dibrugarh University, Dibrugarh 786 004, India
3 Regional Training Institute, Geological Survey of India, Eastern Region, Kolkata 700 091, India
 

Shillong Group comprises a thick meta-volcano-sedimentary sequence forming a part of Shillong Plateau and Mikir Hills. The litho variants of felsic meta-volcanics are characterized in detail based on their constituent material, textural variation, depositional feature and mode of eruption. Lava flows are characterized as porphyritic, spherulitic and aphyric type whereas pyroclastic deposits are classified as tuff breccia, lapilli tuff, tuffand ignimbrite. Fractured crystal and brecciated lithic fragments in tuff; fiamme and eutaxitic texture of ignimbrite suggest for subaerial eruption. The felsic meta-volcanics are rhyolitic to dacitic in composition and interbedded with tuffaceous phyllite, phyllite and quartzite.

Keywords

Felsic Volcanics, Ignimbrite, Lava Flow, Tuff, Shillong Group, Subaerial.
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  • Characteristics of Mesoproterozoic Felsic Meta-Volcanics from the Shillong Group of Rocks, Meghalaya, North East India

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Authors

R. R. Naik
Geological Survey of India, North Eastern Region, Shillong 793 003, India
K. Theunuo
Geological Survey of India, North Eastern Region, Shillong 793 003, India
T. K. Goswami
Department of Applied Geology, Dibrugarh University, Dibrugarh 786 004, India
M. A. Khonglah
Geological Survey of India, North Eastern Region, Shillong 793 003, India
T. Pal
Geological Survey of India, North Eastern Region, Shillong 793 003, India
S. K. Tripathy
Regional Training Institute, Geological Survey of India, Eastern Region, Kolkata 700 091, India

Abstract


Shillong Group comprises a thick meta-volcano-sedimentary sequence forming a part of Shillong Plateau and Mikir Hills. The litho variants of felsic meta-volcanics are characterized in detail based on their constituent material, textural variation, depositional feature and mode of eruption. Lava flows are characterized as porphyritic, spherulitic and aphyric type whereas pyroclastic deposits are classified as tuff breccia, lapilli tuff, tuffand ignimbrite. Fractured crystal and brecciated lithic fragments in tuff; fiamme and eutaxitic texture of ignimbrite suggest for subaerial eruption. The felsic meta-volcanics are rhyolitic to dacitic in composition and interbedded with tuffaceous phyllite, phyllite and quartzite.

Keywords


Felsic Volcanics, Ignimbrite, Lava Flow, Tuff, Shillong Group, Subaerial.

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DOI: https://doi.org/10.18520/cs%2Fv118%2Fi7%2F1123-1128