Q. 81: How do you reconcile CPT with evidence for multiple Wilson Cycles in Earth’s past?

CPT Q. #81 – 101 Q&A on Catastrophic Plate Tectonics

Question: 81. I want to first say that I appreciate the time that you have put into this review process, and I especially appreciate your willingness to answer our questions in detail. Unfortunately, in the last round you broached a subject that I think deserves a detailed response (or at least an educated guess). I am referring to Wilson Cycles. You mentioned that these plate movements would have been “complex,” but could you at least provide us with a plausible process that could have resulted in multiple “start and stop” tectonic events that seem to be supported by the geological evidence (i.e., North Atlantic Ocean Basin)? The mechanism in CPT seems to be unidirectional in nature, but how do you reconcile this aspect of your theory with the evidence for multiple Wilson Cycles in various locations in Earth’s past? The density differences in ocean floor material due to temperature differentials do not seem to be sufficient to drive additional plate tectonics. Are changes in velocity differentials between multiple subduction zones and seafloor spreading centers and their respective effects (pushing and pulling) acting in the confines of Earth’s relatively-fixed surface area during one runaway subduction event the key factor? Please provide at least one plausible series of events and the reasons for the relative motions (in a time progressive cause and effect order).

Response: I do not think there are sufficient clues for me to say much that is definitive. So you are basically pressing me to speculate, which I will do only with reluctance. Let me begin, however, by saying that from my own modeling experiments to identify which forces play the dominant role in driving plate motions, I have found that forces acting at the plate boundaries overwhelming dominate over the drag forces acting on the bottom of the plates. This is due primarily to the extreme weakness of the asthenosphere. Next, let me remark that I consider forces responsible for the closing of the Iapetus the most problematic aspect of the scenario we are trying to understand. Without too much difficulty, I can imagine the opening of the Iapetus being driven by the upwelling of a large blob of hot material rising rapidly from the core-mantle boundary to rift what is called Laurentia, or the North American craton, away from the pre-Flood supercontinent and push this continental block westward to form the Iapetus Ocean. Similarly, I can imagine another hot blob of material rising soon afterward beneath the oceanic region west of Laurentia and exerting edge forces to drive it back eastward again to close the Iapetus Ocean. This would be a rather clean and simple way for this scenario to unfold. In this case the first stages of CPT would involve the rising of hot blobs from the core-mantle boundary in a runaway manner, action which then triggers the sinking of cold material from the upper mantle to drive the subsequent supercontinent breakup formation of the present Atlantic and Indian Ocean basins.