Paleomagnetism and geochronology of the Gwalior Sills,Bundelkhand craton,Northern India Block: New constraints on Greater India assembly |
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| Institution: | 1. Department of Geology, University of Delhi, Delhi, India;2. Geological Survey of India, Jaipur, India;3. Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima, Japan;4. Sedimentology and Quaternary Geology Group, Wadia Institute of Himalayan Geology, Dehradun, India;5. Hiroshima Institute of Plate Convergence Region Research, Hiroshima, Japan;1. Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway;2. Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France;3. Department of Earth and Planetary Sciences, University of Florida, Gainesville, FL, United States;4. Northland Pioneer College, Show Low, AZ, United States;5. Department of Earth Sciences, University of Western Ontario, London, ON, Canada;6. Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, Brazil;7. School of Geosciences, University of Witwatersrand, Johannesburg, South Africa |
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| Abstract: | We present an updated paleomagnetic pole from the Gwalior Sills in the Bundelkhand craton within the Northern India Block (NIB). Geochronological results from baddeleyite grains from one of the sills yielded an age of 1719 ± 7 Ma which together with a previously published age indicates the emplacement of sills between 1712 and 1756 Ma (∼1730 Ma). The paleomagnetic pole calculated from additional sites in this study, combined with previous studies, falls at 13.5°N, 173.7°E (A95 = 3.6°, K = 98) indicating near equatorial latitudes for northern India. Limestone sampled a few meters above the contact with the sill exhibits similar directions consistent with having been baked by the sill. The pole does not resemble any younger poles from Peninsular India and receives a reliability score of R = 5. Dykes in the Singhbhum craton are slightly older (1765 Ma) and indicate low paleolatitudes for the Southern Indian Block (SIB). Although the Gwalior and Singhbhum poles data indicate low latitudes for both the NIB and SIB, they are statistically different and indicate that a rotation of at least 65° is required to bring the poles into accord. We propose that the NIB and SIB were in proximity but were separated by an ocean basin. We propose the name Gotosindhu (‘Ancient Sea’) for the body of water separating the NIB and SIB. We also review previous models for the assembly of the Columbia supercontinent during this time and critically examine the position of the NIB/SIB in those reconstructions. |
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| Keywords: | Northern India Block Paleomagnetism Geochronology Columbia Gotosindhu |
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