Explanation:

Deccan traps are formed by vast outpouring of basic lava  from many linear fissures developed in the earth’s crust. This outpouring was of quiet type and hence did not create any volcanic domes. It just spread across the surface. This  outpouring was in many active stages followed by periods of quiescence. This outpouring took place around 65 million years ago when India was near present placed Madagascar  and  during its movement towards north, it passed over Reunion Hotspot. Presently this hotspot is dormant in nature. This outpouring lasted for 5million years approx according to latest study.