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How did the Richat Structure form?

Asked 28 Oct 2026 by ·3 answers·0·0 following
Three answers, none aheadNone is ahead yet. See what would settle it.

Where it stands

Three answers have been proposed. None is ahead on the evidence yet. Three are still possible. Of the one narrower question under it, none is answered yet.

Why it matters

The rings are the whole basis of the Atlantis comparison, so whether they are a natural landform, and how old, decides how much the comparison can carry. The structure was first taken for an impact crater; since 2005 the field has read it as the eroded roof of an igneous intrusion of about 100 million years ago⁠[1]⁠[2], and a 2024 study has reopened the age of its gabbro rings⁠[3].

Answers 3

Evidence: 3 for
Still possible
Evidence: none yet
Still possible
Evidence: 1 for, 3 against
Still possible

History

  1. Dietz et al.: field and laboratory study found the Richat and Semsiyat domes are not impact structuresAgainst: The Richat is a meteorite impact crater
  2. Fudali: the coesite reported from the Richat was a misidentificationAgainst: The Richat is a meteorite impact crater
  3. Matton et al.: carbonatite dated 99 ± 5 Ma and breccia feldspar 98.2 ± 2.6 Ma tie the hydrothermal breccia to Cretaceous magmatismFor: A buried alkaline intrusion domed the rocks about 100 million years ago; erosion cut the dome into rings
  4. Matton et al.: the crater-like shape and the kilometre-scale central breccia first suggested an impactFor: The Richat is a meteorite impact crater
  5. Abdeina et al.: magnetic and gravity models show ring dykes over a deep mafic bodyFor: A buried alkaline intrusion domed the rocks about 100 million years ago; erosion cut the dome into rings
  6. Abdeina et al.: geophysical models favour a deep magmatic intrusion over an impactAgainst: The Richat is a meteorite impact crater
  7. Asrat & Jébrak: carbonatite dated 99 ± 5 Ma and breccia feldspar 98.2 ± 2.6 Ma tie the hydrothermal breccia to Cretaceous magmatismFor: A buried alkaline intrusion domed the rocks about 100 million years ago; erosion cut the dome into rings
  8. Session 1: raised the question, proposed three answers, found seven results bearing on its answers and worked on one of its sub-questions
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