James D. Witts Profile picture
Geologist, palaeontologist, geochemist post-doc @UNM. Interested in #extinction, #evolution, #molluscs, #geochemistry & #Antarctica. Views my own. UK ↔ USA
31 Mar 19
Interesting outcome of the DePalma et al #PNAS paper will be implications for study & interpretation of K-Pg 'Event Deposits' close to the #Chicxulub crater. These are fascinating outcrops which *could* record the same processes as 'Tanis' but have proved controversial.. (1/)
Many marine K-Pg boundary sites around the Gulf of Mexico contain evidence for high-energy deposition by processes linked to the immediate aftermath of the impact event such as earthquakes, tsunamis/seiches. But a 'catastrophist' vs. 'non-catastrophist' debate has raged.. (2/)
The 'non-catastrophist' argument has centered on biostratigraphic evidence - i.e. that diagnostic Cretaceous #fossils are found stratigraphically *above* these deposits - and suggestions they are sequence boundaries/lags/hiatuses linked simply to sea level change. (3/)
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