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With the proper composition and mass, is it possible for a planetary body to collide with Earth and embed itself onto the mantle?

To clarify, while immense destruction would undoubtedly occur to the hypothetical body in question, could such an event produce a visible landform such as a plateau or mountains?

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    $\begingroup$ Under certain conditions, an impact crater can have a central peak. But that peak consists mostly of material from the impacted body, not of the impactor. Would that work for your story or do you need the peak to be made only of the impactor? $\endgroup$ – Philipp Oct 26 '19 at 11:54
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    $\begingroup$ Traditional craters would not form when planets collide. The energies involved would be many orders of mangnitude greater than what is seen in the formation of even the largest craters. $\endgroup$ – Slarty Oct 26 '19 at 13:50
  • $\begingroup$ What is your actual underlying goal here? Do you basically want a mountain range composed of matter from the colliding world, rather than "native" rock? (inasmuch as "native" means anything, following that whole Theia thing). $\endgroup$ – Starfish Prime Oct 26 '19 at 14:54
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No as L. dutch pointed out impactor either leave a crater or liquefy completely,

however there is a way to get a plateau on the opposite side of the plant from an impactor.

With a large impactor the shock-waves coalescing on the other side of the planet can trigger flood basalts, which can form plateaus. in fact a large number of plateaus are created by flood basalts directly or the differential erosion of flood basalts.

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I sense some confusion in your question.

The mantle lays deep below the crust, therefore if a body goes into the mantle won't be visible on the surface.

Earth structure

But let's proceed with order.

As you correctly guess, an impact with a planetary body will bear large destruction. The energy at stake is so large that the entire planet would be melted. As a consequence of the melting, the liquids would stratify according to their density: denser materials would go down, lighter materials would float.

Therefore, if the colliding body was made by a high density material, like iron, it would sink, going into the mantle or below, into the core.

Moreover, since the whole planet would be liquid, there is no chance that surface features higher than the average level would be permanent. For that to happen, you need a solid crust. But once that is present, stratification has already worked.

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  • $\begingroup$ The reason for my wording is because I was picturing a body large enough to reach the mantle without fully passing through the crust in its entirety. $\endgroup$ – Wax Oct 27 '19 at 0:31

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