New 39Ar-40Ar Ages of Dykes from Madhya Pradesh and Chhattisgarh: Evidence for Polyphase Dyke Intrusion in Eastern Deccan Volcanic Province

Mafic dykes constitute an important component of the Deccan Volcanic Province. The duration of Deccan volcanism was from 69 to 63 Ma with a peak at 65 ± 1 Ma. The thickness of the lava flows is much reduced and intensity of dyke occurrence is much less in the eastern part of the province compared to the western part. Here we report new ³⁹Ar-⁴⁰Ar plateau ages of 60.1 ± 0.3 Ma (2σ) and 82.3 ± 0.7 Ma (2σ) of two mafic dykes from Shahdol (Madhya Pradesh) and Chirimiri (Chhattisgarh), which indicate polyphase dyke intrusion in the eastern Deccan Volcanic Province.