The article claims " Likely reworked" ... which it wasn't. The K/T boundary is a fairytale, and no it doesn't exist. Neither does the Geological Time Column Exist.
Many years ago I was the wellsite geologist working on an exploration well offshore, Kenya named Kofia-1. Kofia-2 was never drilled because the Kofia-1 well (costing 27 million dollars) was a dry hole. What was thought to be the top of the Creataceous was mapped using seismic data, and the depth to this horizon estimated. The well was sited over what appeared to be a large structural high, resembling a dome. This was the potential trap for an oil accumulation. It was hypothesized that the start of the prospective section that would possibly contain sandstone reservoirs would start at this boundary where a change in lithology would occur.
After drilling a few hundred feet of limestone that was basically made of coralline debris, we drilled into the lithology predicted for the Tertiary section, green claystone. The Cretaceous section was thought to be made up of hardened shales and inter-bedded sandstones.
When we reached the predicted depth for the top of the Creataceous we still were seeing green claystone in the cuttings, and only green claystone, It was however quite fossiliferous with many forams visible under the microscope. When compared with some charts that a muddloger had brought out, they matched well with some diagnostic Tertiary species. Something appeared to have gone wrong with the seismic map. We were about 500' deeper than our intended horizon yet we were still drilling claystone of the same color that looked very much the same as what we had been drilling for thousands of feet. But suddenly all the fossils had radically changed. The forams were almost the same size as the ones we had seen in the shallower section, but the ornamentation was very different. They matched the species shown in the charts for Cretaceous forams. There were a couple of diminutive ammonites as well.
I contacted London and told the people in the office there that we had penetrated the top of the Creataceous. They were very skeptical, apparently feeling there was no way we would be able to ascertain this at wellsite. We had not been asked to look at fossils, but just lithologic changes. I was asked to "hot-shot" some sample to Wales for study by Robertsons Research. A couple of days later there results indicated the top of the Cretaceous just 15' shallower than our pick offshore.
The depositional environment had not changed much during the entire section we drilled after the limestones were penetrated.An open-marine environment was indicated with the only dramatic change being in pelagic forams preserved in the rocks. These tow were indicative of deposition in ocean waters. We only encountered
two thin sandstone beds in the entire section, and these were near TD.
That is how geologists can locate and define where the boundaries of the geologic time scale appear in outcrops or in the subsurface. This allows us to correlate time equivalent rocks worldwide. The forams in locations thousands of miles away would show the same or very similar changes to what I saw in Kofia-1, even if they were not found in green claystones.