Tectonics of the SW Pacific Region as an Analogue for the Mesozoic Tectonics of the North American Cordillera

The tectonic processes ongoing in the Southwest Pacific provide an ideal modern analogue for events shaping the North American Cordillera during Mesozoic time. The Cordillera experienced a long period of arc and back-arc activity, arc-continent collisions, oceanic plateau collisions, massive translational and local rotational movements, and amalgamation of collisional blocks. In addition, the major uplift of the Rocky Mountains with both thin-and thick-skinned thrusting occurred during this period, with the accompaniment of very alkaline volcanism in the Rocky Mountain uplift zones. Finally, periods of significant subduction accretion and non-accretion or erosion marked this period. These processes are presently occurring in the SW Pacific. The modern Andes also provide an excellent analogue to the Mesozoic Rocky mountain structures, but they do not show the rich history of arc and ocean plateau collision that are seen in the SW Pacific. Here I show specific examples from the tectonics of Indonesia and Papua New Guinea to illustrate the complexity of events resulting from oblique plateau collision, arc reversal and ensuing collisions, continental sliver collisions and small ocean basin closing. I also discuss the spatial and temporal changes in subduction erosion vs accretion in producing a rock record of these events.