BACK-ARC ZONES OF THE ACTIVE WEST PACIFIC MARGIN: AN ANALOG OF ATLANTIC-TYPE PASSIVE MARGINS AND THEIR PETROLEUM POTENTIAL

Abstract

The origin of present-day continental margins of the oldest part of the Pacific Ocean is related to the Late Mesozoic. A single geodynamic system of marginal seas, island arcs, and deep-sea trenches, which emerged along the West Pacific margin in the Middle Cretaceous, continued to evolve and extended from the south to north throughout the Cenozoic. Back-arc spreading, which repeatedly showed up in the Cretaceous and Paleogene, played an important part in the development of seas. This process promoted the expansion and deepening of sea basins with the formation of deep-water basins in some areas. Therefore, the study region incorporates different proportions of shelf (adjoining macroand microcontinents) areas with the consolidated crust and deep-water areas with the newly formed oceanic (or transitional to oceanic) crust.