Departments Seminar - Munir Humayun

Mar 28, 2023, 12:30 pm1:20 pm
Guyot Hall 10
All Welcome



Event Description

The discovery of an enrichment of the element iridium (Ir) in a clay layer marking the Cretaceous-Paleogene (K-Pg) boundary led to the meteorite impact theory for the end-Cretaceous extinction. This theory has been corroborated by much subsequent evidence including recognition of the Chicxulub crater as the point of impact. What could possibly be wrong with a theory that has dominated our understanding of the K-Pg event for four decades? Here, I show with laser ablation ICP-MS measurements of elemental enrichments at the K-Pg boundary at El Kef (Tunisia) that iridium and other metals are enriched in proportions characteristic of the terrestrial crust, not of any known type of meteorite. Pyrite oxidation provides a mechanism by which metals are enriched in ‘red’ clay. I will discuss the effects of the coeval Deccan eruptions on trace metal abundances in contemporaneous sediments and outline future tests of the two explanations.



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