Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up
The effects of deformation and concomitant high‐grade metamorphism during the Cenozoic period in the active Himalayan orogen hinder the reconstruction of the original geological framework and thus the evolution history. The Shillong Group in the Shillong Plateau, northeastern India, rests unconforma...
Published in: | Geological Journal |
---|---|
Main Authors: | , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2021
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/pdf/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/gj.4325 |
id |
crwiley:10.1002/gj.4325 |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1002/gj.4325 2024-04-28T08:01:51+00:00 Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up Deb, Gautam Kumar Ray, Arijit Presidency University 2021 http://dx.doi.org/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/pdf/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/gj.4325 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Geological Journal volume 57, issue 2, page 647-661 ISSN 0072-1050 1099-1034 Geology journal-article 2021 crwiley https://doi.org/10.1002/gj.4325 2024-04-08T06:52:29Z The effects of deformation and concomitant high‐grade metamorphism during the Cenozoic period in the active Himalayan orogen hinder the reconstruction of the original geological framework and thus the evolution history. The Shillong Group in the Shillong Plateau, northeastern India, rests unconformably above the Himalayan crystalline basement gneiss, and is divided in two formations, the Lower Metapelite Formation (LMF) and the Upper Quartzite Formation (UQF). There are three horizons of conglomerate: (a) Basal, between the basement and the Shillong Group, (b) an inter‐formational conglomerate, between the LMF and UQF, and (c) an intra‐formational conglomerate (within the UQF). The clasts of the latter two conglomerates are suitable strain markers. Principal compressional structures in the Shillong Group were developed in two successive deformation episodes during the Meso‐ to Neo‐Proterozoic period. The earlier episode was of progressive general shear deformation, while the later one possibly occurred in a transpressive mode similar to that of a fold‐thrust belt. Remarkably, both episodes underwent NW–SE regional compression. The inter‐formational conglomerate represents a flattening type strain of relatively lesser magnitude ( R f – ϕ X : Y : Z = 1.35:1:0.76), in contrast to the constriction type strain of relatively higher magnitude ( R f – ϕ X : Y : Z = 2.42:1:0.44) of the intra‐formational conglomerate. Field relations of the Shillong Group with the deformed and undeformed granite plutons suggest that the earlier deformation episode possibly took place during Rodinia assembly, due to India–Antarctica collision at 1,100 Ma, while the later one happened in a time frame close to 500 Ma, during the amalgamation of Eastern Gondwana. Article in Journal/Newspaper Antarc* Antarctica Wiley Online Library Geological Journal 57 2 647 661 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
topic |
Geology |
spellingShingle |
Geology Deb, Gautam Kumar Ray, Arijit Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
topic_facet |
Geology |
description |
The effects of deformation and concomitant high‐grade metamorphism during the Cenozoic period in the active Himalayan orogen hinder the reconstruction of the original geological framework and thus the evolution history. The Shillong Group in the Shillong Plateau, northeastern India, rests unconformably above the Himalayan crystalline basement gneiss, and is divided in two formations, the Lower Metapelite Formation (LMF) and the Upper Quartzite Formation (UQF). There are three horizons of conglomerate: (a) Basal, between the basement and the Shillong Group, (b) an inter‐formational conglomerate, between the LMF and UQF, and (c) an intra‐formational conglomerate (within the UQF). The clasts of the latter two conglomerates are suitable strain markers. Principal compressional structures in the Shillong Group were developed in two successive deformation episodes during the Meso‐ to Neo‐Proterozoic period. The earlier episode was of progressive general shear deformation, while the later one possibly occurred in a transpressive mode similar to that of a fold‐thrust belt. Remarkably, both episodes underwent NW–SE regional compression. The inter‐formational conglomerate represents a flattening type strain of relatively lesser magnitude ( R f – ϕ X : Y : Z = 1.35:1:0.76), in contrast to the constriction type strain of relatively higher magnitude ( R f – ϕ X : Y : Z = 2.42:1:0.44) of the intra‐formational conglomerate. Field relations of the Shillong Group with the deformed and undeformed granite plutons suggest that the earlier deformation episode possibly took place during Rodinia assembly, due to India–Antarctica collision at 1,100 Ma, while the later one happened in a time frame close to 500 Ma, during the amalgamation of Eastern Gondwana. |
author2 |
Presidency University |
format |
Article in Journal/Newspaper |
author |
Deb, Gautam Kumar Ray, Arijit |
author_facet |
Deb, Gautam Kumar Ray, Arijit |
author_sort |
Deb, Gautam Kumar |
title |
Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
title_short |
Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
title_full |
Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
title_fullStr |
Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
title_full_unstemmed |
Deformation of the Shillong Group rocks, Shillong Basin, Meghalaya, north‐east India: Implication on the Proterozoic supercontinent build‐up |
title_sort |
deformation of the shillong group rocks, shillong basin, meghalaya, north‐east india: implication on the proterozoic supercontinent build‐up |
publisher |
Wiley |
publishDate |
2021 |
url |
http://dx.doi.org/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/pdf/10.1002/gj.4325 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/gj.4325 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Geological Journal volume 57, issue 2, page 647-661 ISSN 0072-1050 1099-1034 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/gj.4325 |
container_title |
Geological Journal |
container_volume |
57 |
container_issue |
2 |
container_start_page |
647 |
op_container_end_page |
661 |
_version_ |
1797573422311538688 |