Plate Tectonics of the North American Continent at the Cretaceous-Tertiary Boundary and Implications for a Terrestrial Cause In the Great KT Extinction Controversy

The debate rages on over the exact cause of the mass extinctions that occurred at the Cretaceous-Tertiary boundary of 65 mya. The most widely accepted hypothesis states that a huge asteroid crashed into the earth sending dust and debris into the atmosphere that blocked out the sun, causing an “impact winter”. Other scientists claim that the KT boundary layer contains evidence of a volcanic origin. Most, however, point to the Deccan Traps of India as the cause.

This paper will introduce a new hypothesis on the KT Extinctions of 65 mya, and will attempt to show that all of the evidence found within the KT boundary layer can also be explained by another event that was occurring at the same time as the Deccan Traps of India, but on the other side of the world from it. This event has been recorded geologically by the presence of the Franciscan mélange and Coast Range Ophiolite that make up most of California. All of the materials found within the KT boundary layer: high levels of iridium, rhenium-osmium, glass spherules, shocked quartz, andesite, and bits of granite can also be explained by the closing off of a mid-ocean ridge and/or ocean island hotspot as it was being thrust beneath the continental plate of North America, 65 million years ago. From the Coast Range Thrust, to the uplifting of the Kaibab plateau and the Laramide Orogeny, resulting in the disappearance of the Western Interior Seaway; this paper will explore the actual geologic record of the North American continent to get a more complete picture of what was happening, tectonically, at the KT boundary and will propose that the true cause of the KT Extinctions was the result of Terrestrial rather than Extraterrestrial forces.