Tectonic processes, from rifting to collision via subduction, in SE asia and the western pacific: A key to understanding the architecture of the Central Asian Orogenic Belt

Abstract

We review the processes of accretion of continental blocks during the Tertiary in SE Asia and the western Pacific with the aim of better understanding the evolution of the Central Asian Orogenic Belt, which is a Neoproterozoic to mid-Phanerozoic orogenic collage surrounded by the East European, Siberian, Tarim, and North China cratons. In the western Pacific, there is abundant evidence of sequential plate-tectonic processes from accretion to continent-arc/continent collision, via exhumation and suprasubduction. Early processes involve seafloor spreading, subduction, accretion, arc formation, and back-arc extension. Two important types of tectonic setting and evolution are recognized along the present Pacific convergent margin: sediment/crust accretion and tectonic erosion. Five major accretionary complexes are well illustrated in the Japanese Islands. Tectonic erosion removes material by underscraping the lower part of the upper plate. Subduction is also associated with back-arc extension, particularly in Indonesia and the SW Pacific region. Arc-arc collisional complexes are present in Taiwan, the Philippines, and Japan. The geological record of SE Asia and the western Pacific provides a robust modern analogue for the geological and tectonic history of the Central Asian Orogenic Belt, before it was affected by high-temperature metamorphism. © 2013 Geological Society of America.