What could have caused a worldwide Catastrophe that produced the Quarternary fossil beds?

I am writing a book on the Tertiary and Quarternary. I believe that there was an asteroid impact that produced the KT Boundary, and I am researching the Quarternary to see if something similar produced these fossil beds. The geologic/paleontological evidence has convinced me something suddenly buried these mammals all over the world in surficial deposits like: caves, gravel, sand, silt beds, bogs, and asphalt seeps. At this same time the weather also suddenly changed that froze mammoths all over Alaska and Siberia. There were also volcanic eruptions at this time. Have any ideas? If you do, please give me your e-mail address so we can discuss this further.