Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/14845
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
Contributor(s): Ali, Jason R (author); Aitchison, Jonathan C (author); Chik, Sam Y S (author); Baxter, Alan  (author); Bryan, Scott E (author)
Publication Date: 2012
DOI: 10.1016/j.jseaes.2012.01.007
Handle Link: https://hdl.handle.net/1959.11/14845
Abstract: 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.
Publication Type: Journal Article
Source of Publication: Journal of Asian Earth Sciences, v.50, p. 105-115
Publisher: Pergamon
Place of Publication: United Kingdom
ISSN: 1878-5786
1367-9120
Field of Research (FOR): 040313 Tectonics
040406 Magnetism and Palaeomagnetism
Socio-Economic Objective (SEO): 970104 Expanding Knowledge in the Earth Sciences
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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