Question Concerning Meteorite Ejecta Travel
The research doesn't provide enough information to specify the displacement process of a 0.1mm spherule over 12,000 kilometers from North Greenland to Chile.
If the suggested impact was from Greenland, the space rock would have hit 800 to 1200 meters of ice at perhaps 10km/s which is the average for that kind of event.
Mount St Helens was about 0.25 km3 of ejecta, and the Greenland impact was a lot higher, i.e. 20km3 of vaporized rock.
Volcanoes send the energy out over many hours, whereas a YD meteorite would convert the energy relatively fast, perhaps mostly in the first 2 seconds. The thermal energy would have been very high, and the ejecta would have reached every level of the stratosphere, and the earthquakes would have emptied some lakes out in North America and left some major destruction fields in North America.
The same atmospheric displacement effects for all kinds of recent volcanoes would have been out measured considerably by a YT event.
Perhaps further studies will change the impactor site from the Greenland one which is perhaps 200k years old, to one in the Southern Hemisphere. At the moment, the evidence is so fleeting that the Nature article you gave has only generated a few lines of text on Wiki.