iirc part of a huge crater has been found in what is antarctica (the rest of the crater in theory should be part of the australian plate) which appears to date to this event.
The crater IIRC was far larger than K-T crater/yucatan impact, I will see if I can find the article.
I have always though that the Siberian Trapps may have flowed out of a giant meteor strike. I also had the same thought about the Deccan Trapps in India which were built at the time of the dinosaur extinction. There is some talk of a 400 by 600 mile?/km? crater in that area known as the Shiva crater.