4
$\begingroup$

A meteor crashes in a very geologically unstable region of an earth-like planet.

A few years later, a person visiting that site will find the following features:

  1. A concave depression, of a circular (or nearly circular) shape, with at least 1 Km of diameter, with an elevated rim all around it.
  2. A mountain located within the depression and towering above the rims. The mountain does not need to be very high, but it needs to be high enough to be considered a mountain. It can be located at the center of the depression or at its edge or anywhere in between those two points.

My question is: could this geological arrangement be achieved? I have searched online and have not found any examples, but I also know this scenario is very specific.

By mulling on this, I have reached two possible explanations that could yield this result:

Explanation 1): The meteor creates a huge impact crater, and then proceeds to trigger a volcanic eruption which creates a new mountain.

Explanation 2): A meteor hits the vicinity (or even the mouth) of an already unstable super-volcano. This meteor is not big enough to raze the mountain, but the force of the impact is enough to trigger a massive volcanic eruption. This eruption empties the magma chamber very quickly, causing the partial collapse of the volcano, forming a caldera around it, whereas the peak of the volcano still remains and forms the mountain.

Is any of these explanations plausible, at least in theory? Or is there another explanation that could produce the desired effect (as long as it involves an eruption following a meteor impact)?

$\endgroup$
4
  • 5
    $\begingroup$ That's called a central-peak crater. Not uncommon. The Mistastin crater is an example on Earth; on the Moon there are many such craters, with crater Tycho being an example. To get an intuitive feeling of how they form, see this slow motion video of a drop of water falling onto a still water surface. $\endgroup$
    – AlexP
    Nov 29, 2020 at 19:54
  • $\begingroup$ Thank you very much. Is there any other example on Earth beside Mistastin crater? I don't seem to find many (non-sattelite) pictures of it $\endgroup$ Nov 29, 2020 at 21:39
  • 5
    $\begingroup$ Note the peak in a central peak crater are never taller than the height of the rim in a fresh crater. If you need the peak to tall and large give up on the impact crater and go with a atoll or volcano. sciencedirect.com/science/article/abs/pii/0019103573900237 $\endgroup$
    – John
    Nov 29, 2020 at 21:42
  • 2
    $\begingroup$ Manicouguan crater (quite spectacular). Gow crater. Aorounga crater. Gosses Bluff crater. (Search for central peak crater, or peak ring crater.) $\endgroup$
    – AlexP
    Nov 29, 2020 at 22:01

1 Answer 1

10
$\begingroup$

Yes. That is ABSOLUTELY NORMAL behavior for crater formation, when the impacting meteor hits reasonably vertically.

Neither of your explanations are necessary though, the formation of the central uplift peak is a natural and intrinsic aspect of crater formation. The technical term for it is "Complex Crater" In short, it is caused by the impacted ground in the middle of the crater resurging upwards.

image from wikipedia page about this: enter image description here

$\endgroup$
5
  • 3
    $\begingroup$ you could also do this by having the impact happen ins volcanically active area, the weakened crust could case a new volcano to form in the center. $\endgroup$
    – John
    Nov 29, 2020 at 21:37
  • 1
    $\begingroup$ Thank you very much. A few questions though: 1) From all the figures I have seen, it seems like the mountain would be lower than the rims. Would that be the case always or is it possible for the inner mountain to tower over the rims? 2) It seems like in this arrangement ("central peak crater" in Wikipedia) the mountain would be relatively central relative to the crater? Is that correct, or could it be eccentrical, nearer the periphery? $\endgroup$ Nov 29, 2020 at 21:38
  • 5
    $\begingroup$ The height of the central peak is directly related to the diameter of the crater, a 1km crater will never have a large central peak. sciencedirect.com/science/article/abs/pii/0019103573900237 $\endgroup$
    – John
    Nov 29, 2020 at 21:46
  • $\begingroup$ Thank you @John. The crater does not need to be 1 Km though, but "at least" 1 Km, so it can be as big as it would allow a large central peak. I also like your idea of a new volcano forming in the center of the crater $\endgroup$ Nov 29, 2020 at 22:00
  • 1
    $\begingroup$ Basically, at high enough velocities and large enough scales, solid objects behave like a liquid. $\endgroup$ Nov 30, 2020 at 12:37

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .