SHRIMP geochronology for the 1450 Ma Lakhna dyke swarm: Its implication for the presence of Eoarchaean crust in the Bastar Craton and 1450–517 Ma depositional age for Purana basin (Khariar), Eastern Indian Peninsula |
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| Institution: | 1. CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500007, India;2. Centre for Tectonics, Resources and Exploration, Department of Earth Sciences, University of Adelaide, SA 5005, Australia;3. School of Earth Science and Resources, China University of Geosciences, Beijing, China;4. Department of Studies in Geology, Karnatak University, Pavate Nagar, Dharwad 580007, India;5. CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam 530017, India;6. Department of Geology, Andhra University, Visakhapatnam 530003, India;1. University of Florida, Department of Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States;2. Department of Geology, University of Rajasthan, Jaipur, Rajasthan, India;3. Geomagnetic Research Laboratory, Regional Center of Indian Institute of Geomagnetism, Allahabad 221 505, India |
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| Abstract: | Zircon U–Pb ages of the Mesoproterozoic dyke swarms (Lakhna dyke swarm) at the interface between the Eastern Ghats Mobile Belt and Bastar Craton of the Indian Peninsula are reported here to decipher the tectonic evolution of the region. The dyke swarm, which is dominantly N–S in orientation, has intruded the Bastar Craton at ca. 1450 Ma. The dykes vary in composition from dolerite to trachyte and rhyolite and have been emplaced in a continental anorogenic setting. The above age puts a lower time constraint on the sedimentary sequences of the Purana basin (Khariar basin) that have been deposited unconformably over the Bastar Craton. The shale member of the Khariar basin shows evidence of synsedimentary shearing suggesting that the sedimentation probably continued up to 517 Ma, the age of shearing and overthrusting of the granulite nappes of the Eastern Ghats Mobile Belt on the Craton. Further, the compression accompanying thrusting of the nappes, uplifted the Purana basins during inversion. |
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