The Rajmahal Traps of India - KAr ages and palaeomagnetism

Abstract

A number of concordant KAr ages in the range 100 to 105 my have been measured on samples from the tholeiitic Rajmahal Traps of India. These results are interpreted as giving a good estimate of the time of eruption of the basalts. By comparison with the physical time scale, this age is late Early Cretaceous (Albian). The isotopic ages can be reconciled with the conflicting views expressed by previous workers on the age of the Rajmahal Traps on the basis of palaeontological studies. Palaeomagnetic measurements on the basalts yield a palaeomagnetic pole in excellent agreement with previous work. The polar-wander path for the Phanerozoic of India is reviewed in the light of the age of the Rajmahal Traps and apparent inconsistencies in some of the previous data. This results in a reconsideration of the stratigraphic position of some of the beds sampled for palaeomagnetic purposes. Show more