The case for creation of the North Pacific Ocean during the Mesozoic Era

Abstract

Pangean reconstructions based on the Dymaxion Projection are discussed, and the advantages of placing cordilleran North America alongside eastern Asia are clearly seen. A detailed matching of the western North American and eastern Asian continental margins shows that the North Pacific can be closed as tightly as the Atlantic when appropriate adjustments are made to reproduce Permian geography. Closure of the North Pacific eliminates overlap of cordilleran North America with South America in the Caribbean region and permits closure of the Arctic Ocean. Geological and paleontological data are presented which permit a tentative Phanerozoic history of the North Pacific to be outlined. According to this view, cordilleran North America and the North China craton were rifted from cratonic North America at the dawn of the Phanerozoic. They drifted westward across a proto-Pacific Ocean and were temporarily sutured to the Siberian craton along the Sayanian fold belt during the world-wide Early Paleozoic orogenies. Final suture occurred along the Mongolian fold belt during the world-wide Late Paleozoic orogenies which completed the consolidation of Pangea. Separation of cordilleran North America from eastern Asia was part of the Mesozoic fragmentation of Pangea. Mesozoic sea-floor spreading carried cordilleran North America eastward and opened the present North Pacific. Cordilleran North America was sutured to cratonic North America during the world-wide Cenozoic orogenies. Suture began along the Nevadan-Sevier fold belt and was followed by under-riding along the Laramide fold belt. North America then partly over-rode the East Pacific Rise sea-floor spreading center, and dextral transform faults across the rift valley created faults and oroclines in cordilleran North America. A driving force for the disintegration of Pangea is provided by the unstable tetrahedral convection model. This model is fitted to Phanerozoic world maps for all periods beginning with the Permian to show how an opening North Pacific Ocean can be made compatible with opening of the Atlantic, Indian, and Arctic Oceans. The unstable tetrahedral convection model also provides a mechanism for opening the Cenozoic small ocean basins behind West Pacific island arcs. Such basins form above abandoned convection plumes or curtains which rise passively to the earth's surface. These plumes and curtains are abandoned when the potential energy-driving convection is locally exhausted.