Chicxulub impact crater, Yucatán

Assembled from 13 blocks · 3 evidence · 6 related

1. Story
2. A buried impact structure roughly 180 kilometres across, centred near the village of Chicxulub Puerto on the northern coast of the Yucatán Peninsula, half beneath the peninsula and half beneath the Gulf of Mexico, and covered by about a kilometre of younger carbonate sediment. It was first noticed as a circular gravity and magnetic anomaly by geophysicists prospecting for Pemex in the late 1970s and identified as an impact crater of the right age in 1991, more than a decade after the impact hypothesis was proposed — which is why the hypothesis spent the 1980s without a crater. The target rock matters as much as the size: the Yucatán platform is carbonate and sulfate-rich, so the impact vaporised enormous quantities of carbon dioxide and sulfur, and the sulfate aerosols are the leading candidate for the short, severe global cooling and photosynthesis shutdown that followed. In 2016 an IODP–ICDP expedition drilled the crater's peak ring offshore and recovered granitic basement rock uplifted from depth and then collapsed outward, confirming the dynamic collapse model of how large craters form.
3. Knowledge
4. Chicxulub impact crater, Yucatán
5. Connections
6. The Cretaceous–Palaeogene mass extinction
7. The K–Pg boundary is dated to 66.043 ± 0.043 Ma
8. Chicxulub is identified as the K–Pg impact crater
9. IODP–ICDP Expedition 364 drills the Chicxulub peak ring
10. Evidence
11. Supports the identification of the buried Yucatán structure as an impact crater of Cretaceous–Palaeogene age. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked. Volume and page range are quoted from standing knowledge and were not re-checked.
12. Supports the 2016 peak-ring drilling result at Chicxulub and the dynamic collapse model of peak-ring formation. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked. Volume and page range are quoted from standing knowledge and were not re-checked.
13. Supports the multi-author synthesis position that the Chicxulub impact was the proximate cause of the K–Pg extinction, and the global distribution of the boundary layer with its shocked quartz and spherules. The Deccan Traps alternative continued to be argued after this review; that literature is not cited here. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked. Volume and page range are quoted from standing knowledge and were not re-checked.