Wilson Cycle

The Wilson cycle is a model in plate tectonics describing the repeated opening and closing of ocean basins over geological time, through a sequence of stages beginning with the rifting of a continent, the widening of the resulting ocean basin through seafloor spreading, the eventual initiation of subduction and closure of that ocean, and culminating in continental collision to form a new mountain range as the ocean basin disappears entirely. Canadian geophysicist John Tuzo Wilson proposed the concept in a 1966 paper, drawing on his recognition that the Atlantic Ocean had apparently opened, closed, and reopened along roughly the same zone of weakness across multiple past cycles, evidenced by similar fossil faunas on either side of the modern ocean despite an earlier, now-vanished ocean having once existed along much the same line. The cycle is illustrated by the geological history of the Iapetus Ocean, which opened and then closed during the assembly of the supercontinent Pangaea, leaving behind the Appalachian and Caledonian mountain belts at the resulting continental suture. The Wilson cycle provides plate tectonics with a long-term, repeating framework for understanding the relationship between rifting, ocean formation, subduction and mountain building over hundreds of millions of years.