I was looking at a map of the distribution of mantle plumes, and was wondering if they could be residual material that was either brought here or affected by the Theia impact.

It seems to me that this material would have a distinct temperature difference to the material around it, and that, at the scale and volumes we are talking about, it would take billions of years for the currents to achieve anything resembling equilibrium, if they ever did.

It seems as though the impact might also on another note, be responsible for exactly WHERE, the mantle first hardened into a crust.

Is it possible that the Theia impact was the single event most responsible for the specific evolution of the crust and mantle that we see today and throughout geological history, creating the initial drastic variation in the mantle temperature, the conditions under which the first and subsequent continents would form, and the currents of mantle plumes that rift the crust into the specific plates we have seen through history? And could that possibly help us extrapolate a more precise location of where on Earth that impact took place?

Is there any formal speculation that has been done on this that someone could point me to?

  • $\begingroup$ When Theia impacted, Earth was presumably still in its deep magma-ocean stage. The impact itself heated the planet even more, so convection in the magma would have quickly erased all signatures of where it impacted. The modern mantle plumes are slow moving (turnover time ~ tens of millions of years if memory serves) and are only set by current physics of the planet. $\endgroup$ Jun 12, 2023 at 16:54
  • $\begingroup$ @AtmosphericPrisonEscape Thank you but I would like to clarify my original question. I understand Earth was in its magma ocean stage, but I don't get why any equilibrium would be as fast as you were saying. If a rock mass of that tonnage slammed into a magma ocean of that tonnage, what would cause the mass to incorporate so quickly? I get there would be immense heat, but would that be enough to melt that entire mass into a viscosity that would so readily mix? Wouldn't have a temperature and viscosity that affected the temperature more locally than globally? $\endgroup$ Jun 17, 2023 at 20:58
  • $\begingroup$ The convection that would be active (and still is) is in no way local... $\endgroup$ Jun 17, 2023 at 22:10


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