K/Pg Boundary Event

23 Feb 2019

Geological chronology is at the heart of a division in earth sciences - between those that favour an asteroid impact and those that, instead, blame the Deccan Traps for the demise of the dinosaurs (and various other life forms). The Traps is a large eruption of lava in what is now India. At https://phys.org/print469949649.html ... we have more on the disupte which could easily be resolved if geologists accepted sediments can be laid down quickly on occasion. Sadly, we have had endless arguments since the asteroid impact was first suggested, all bogged down in the dating of sedimentary layers around the event. This is an attempt to compromise as the Deccan Traps are thought to have erupted over a period of thousands of years - up to a million years. The new study in the journal Science (February 2019) says the peak moment of activity in the Traps was much closer to the actual impact thyan previously - 66 million years ago. This is the K/Pg boundary event (otherwise the K/T boundary). The Pg = the Palaeogene period (which follows on from the Cretaceous). The Traps erupted over a period of a million years on the uniformitarian model - and in places the basalt is 2km thick. The study claims the eruption of lava began within 50,000 years of the impact event - which is much closer in time than previously. Is this bonkers? The authors are convinced the impact set in motion the Traps on the opposite side of the Earth - yet are quite happy for an enormous gap between the two. That is the trouble with compromises I suppose. You please no one. It is the uniformitarian nature of the geochronology that is the problem. If sediments were laid down quickly as a result of the impact it opens a quite different agenda - and one that makes sense. Some sleight of hand may have been going on as well as prior to this study 80% of the lava erupted before the impact. Now, it is the other way round. The new study is more realistic as the authors openly think the impact caused the Traps. They consider it likely that the impact generated earthquakes around the world - including basaltic eruptions. They also say volcanic events produce lots of gases - some of which warm the planety, and others, like sulfur aerosols, cool the planet. The impact would also have spewed a lot of dust into the upper atmosphere - which would also have cooled the surface of the earth simply by blocking sunshine. See www.sciencemag.org/content/350/6256/76.full