The Cordillera’s Long-Lived Passive Margin: Neoproterozoic to Middle Devonian Periods: Ca. 1000 Ma–400 Ma

Abstract

With a foundation in place along Laurentia’s western margin, a new phase in the Cordillera’s history began (Table 4.1). As Rodinia split from North America beginning around 1000 Ma, it opened the Panthalassa Ocean (Greek for “all of the sea”). This opening was a seminal event in the Cordillera’s history as it initiated a long-lived passive margin setting. This is a tectonic environment where earthquake and volcanic activity is mostly absent, as opposed to active margins where considerable tectonic activity occurs. This allowed for the deposition of a huge thickness of near-shore and carbonate marine sediments on the newly formed continental shelf and slope-rise. The Eastern Seaboard of the United States is a good modern analog for this type of setting.