Pro-POP: fundamental concepts in favour of the Pacific model
Pro-POP – some of the fundamental concepts1,2,3
- Andean/Cordilleran arc history due to Pacific subduction and the presence of passive Atlantic margins indicate that the Americas have moved westwards in the mantle reference frame during the Atlantic opening history. Lesser Antillean subduction can only be explained by the relative eastward movement of the Caribbean plate with respect to the Americas. Arc magmatism has been more or less continuous with a westward-dipping subduction zone, for the last ~85 Ma4 ~125 Ma3,5, even ~130+ Ma. Assuming 125Ma of westwards subduction at a reasonably slow rate (say 2 cm/yr) the leading edge of the Caribbean plate will have originated 2500 km westward of its present location – that is, in the Pacific.
- Plate motion determinations for the Caribbean and North and South America indicate the Americas did not split until ~160 Ma and the present day Caribbean plate does not fit into the space available geometrically during the Jurassic-Cretaceous.3,5
- Most sedimentary successions in in-situ Caribbean margins do not show any evidence of island arc-related tuffs deposited during the Early Cretaceous, when the Caribbean island arc system was very much active. So the arc was hundreds, nay thousands of kilometres distant - in the Pacific.
- Pacific and Tethyan faunal successions merged only during the late Cretaceous, indicating that the two seaways were previously separate. We should expect to find Tethyan fauna in the older marine sediments of the Caribbean had it been formed “in situ”.
- Seismic tomography actually images the Atlantic slab descending beneath the Caribbean plate - confirming at least 1500km of subduction, and therefore eastward displacement, of the Caribbean plate through time6.
(See main article for references cited)