London, May 4 (IANS): Large impacts can be followed by intense, long-lived and explosive volcanic eruptions -- not just craters, new research has found.

The researchers studied rocks filling one of the largest preserved impact structures on the planet, located in Sudbury, Ontario, Canada. 

The meteorite hit Earth 1.85 billion years ago and excavated a deep basin, 1.5 km-thick.

The researchers found rocks that had melted after the impact, as well as volcanic fragments.

The research, published in the Journal of Geophysical Research: Planets, showed that the composition of the volcanic fragments changed with time. 

Right after the impact, volcanism was directly related to melting of Earth's crust. However, with time, volcanism appeared to have been fed by magma coming from deeper levels within Earth.

"This is an important finding, because it means that the magma sourcing the volcanoes was changing with time. The reason for the excitement is that the effect of large impacts on the early Earth could be more serious than previously considered," said Balz Kamber, Professor at Trinity College Dublin in Ireland. 

On the early Earth there was a relatively brief period during which roughly 150 very large impacts occurred whereas only a handful have hit Earth since then.

"The intense bombardment of the early Earth had destructive effects on the planet's surface but it may also have brought up material from the planet's interior, which shaped the overall structure of the planet," Kamber said.