Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models
Confusion exists as to the age of the Abor Volcanics of NE India. Some consider the unit to have been emplaced in the Early Permian, others the Early Eocene, a difference of ∼230 million years. The divergence in opinion is significant because fundamentally different models explaining the geotectonic...
Published in: | Journal of Asian Earth Sciences |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Pergamon Press
2012
|
Subjects: | |
Online Access: | https://espace.library.uq.edu.au/view/UQ:352557 |
id |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:352557 |
---|---|
record_format |
openpolar |
spelling |
ftunivqespace:oai:espace.library.uq.edu.au:UQ:352557 2023-05-15T13:55:31+02:00 Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models Ali, Jason R. Aitchison, Jonathan C. Chik, Sam Y. S. Baxter, Alan T. Bryan, Scott E. 2012-05-02 https://espace.library.uq.edu.au/view/UQ:352557 eng eng Pergamon Press doi:10.1016/j.jseaes.2012.01.007 issn:1367-9120 issn:1878-5786 orcid:0000-0002-3659-5849 CERG - HKU7002/05 HKU7001/10 CERG - HKU7001/07 Artinskian Bhote Khosi basalts Cimmerian terrane Eastern syntaxis Gondwana 1904 Earth-Surface Processes 1907 Geology Journal Article 2012 ftunivqespace https://doi.org/10.1016/j.jseaes.2012.01.007 2020-10-27T02:41:45Z Confusion exists as to the age of the Abor Volcanics of NE India. Some consider the unit to have been emplaced in the Early Permian, others the Early Eocene, a difference of ∼230 million years. The divergence in opinion is significant because fundamentally different models explaining the geotectonic evolution of India depend on the age designation of the unit. Paleomagnetic data reported here from several exposures in the type locality of the formation in the lower Siang Valley indicate that steep dipping primary magnetizations (mean = 72.7 ± 6.2°, equating to a paleo-latitude of 58.1°) are recorded in the formation. These are only consistent with the unit being of Permian age, possibly Artinskian based on a magnetostratigraphic argument. Plate tectonic models for this time consistently show the NE corner of the sub-continent >50°S; in the Early Eocene it was just north of the equator, which would have resulted in the unit recording shallow directions. The mean declination is counter-clockwise rotated by ∼94°, around half of which can be related to the motion of the Indian block; the remainder is likely due local Himalayan-age thrusting in the Eastern Syntaxis. Several workers have correlated the Abor Volcanics with broadly coeval mafic volcanic suites in Oman, NE Pakistan-NW India and southern Tibet-Nepal, which developed in response to the Cimmerian block peeling-off eastern Gondwana in the Early-Middle Permian, but we believe there are problems with this model. Instead, we suggest that the Abor basalts relate to India-Antarctica/India-Australia extension that was happening at about the same time. Such an explanation best accommodates the relevant stratigraphical and structural data (present-day position within the Himalayan thrust stack), as well as the plate tectonic model for Permian eastern Gondwana. Article in Journal/Newspaper Antarc* Antarctica The University of Queensland: UQ eSpace Indian Journal of Asian Earth Sciences 50 105 115 |
institution |
Open Polar |
collection |
The University of Queensland: UQ eSpace |
op_collection_id |
ftunivqespace |
language |
English |
topic |
Artinskian Bhote Khosi basalts Cimmerian terrane Eastern syntaxis Gondwana 1904 Earth-Surface Processes 1907 Geology |
spellingShingle |
Artinskian Bhote Khosi basalts Cimmerian terrane Eastern syntaxis Gondwana 1904 Earth-Surface Processes 1907 Geology Ali, Jason R. Aitchison, Jonathan C. Chik, Sam Y. S. Baxter, Alan T. Bryan, Scott E. Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
topic_facet |
Artinskian Bhote Khosi basalts Cimmerian terrane Eastern syntaxis Gondwana 1904 Earth-Surface Processes 1907 Geology |
description |
Confusion exists as to the age of the Abor Volcanics of NE India. Some consider the unit to have been emplaced in the Early Permian, others the Early Eocene, a difference of ∼230 million years. The divergence in opinion is significant because fundamentally different models explaining the geotectonic evolution of India depend on the age designation of the unit. Paleomagnetic data reported here from several exposures in the type locality of the formation in the lower Siang Valley indicate that steep dipping primary magnetizations (mean = 72.7 ± 6.2°, equating to a paleo-latitude of 58.1°) are recorded in the formation. These are only consistent with the unit being of Permian age, possibly Artinskian based on a magnetostratigraphic argument. Plate tectonic models for this time consistently show the NE corner of the sub-continent >50°S; in the Early Eocene it was just north of the equator, which would have resulted in the unit recording shallow directions. The mean declination is counter-clockwise rotated by ∼94°, around half of which can be related to the motion of the Indian block; the remainder is likely due local Himalayan-age thrusting in the Eastern Syntaxis. Several workers have correlated the Abor Volcanics with broadly coeval mafic volcanic suites in Oman, NE Pakistan-NW India and southern Tibet-Nepal, which developed in response to the Cimmerian block peeling-off eastern Gondwana in the Early-Middle Permian, but we believe there are problems with this model. Instead, we suggest that the Abor basalts relate to India-Antarctica/India-Australia extension that was happening at about the same time. Such an explanation best accommodates the relevant stratigraphical and structural data (present-day position within the Himalayan thrust stack), as well as the plate tectonic model for Permian eastern Gondwana. |
format |
Article in Journal/Newspaper |
author |
Ali, Jason R. Aitchison, Jonathan C. Chik, Sam Y. S. Baxter, Alan T. Bryan, Scott E. |
author_facet |
Ali, Jason R. Aitchison, Jonathan C. Chik, Sam Y. S. Baxter, Alan T. Bryan, Scott E. |
author_sort |
Ali, Jason R. |
title |
Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
title_short |
Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
title_full |
Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
title_fullStr |
Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
title_full_unstemmed |
Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: significance for Gondwana-related break-up models |
title_sort |
paleomagnetic data support early permian age for the abor volcanics in the lower siang valley, ne india: significance for gondwana-related break-up models |
publisher |
Pergamon Press |
publishDate |
2012 |
url |
https://espace.library.uq.edu.au/view/UQ:352557 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
doi:10.1016/j.jseaes.2012.01.007 issn:1367-9120 issn:1878-5786 orcid:0000-0002-3659-5849 CERG - HKU7002/05 HKU7001/10 CERG - HKU7001/07 |
op_doi |
https://doi.org/10.1016/j.jseaes.2012.01.007 |
container_title |
Journal of Asian Earth Sciences |
container_volume |
50 |
container_start_page |
105 |
op_container_end_page |
115 |
_version_ |
1766262185725526016 |