The Cenozoic tectonic sedimentary evolution characteristics of sedimentary basins in the western Pacific

The Western Pacific is the most developing area of the trench arc basin system in the world, because it is located in the convergent hinge of the European-Asia plate, the Pacific plate and the India-Australia plate, where the... [ view full abstract ]

The Western Pacific is the most developing area of the trench arc basin system in the world, because it is located in the convergent hinge of the European-Asia plate, the Pacific plate and the India-Australia plate, where the plate activities are strong and the tectonic evolution is complicated. Three different types of basins develop in this area, including fore-arc basin, back-arc basin and continental rift basin. Based on the study of regional tectonic environment, the evolution of those basins, stratigraphic fillings, plane sedimentary characteristics and analysis of typical basins among the 14 basins in this area，we made the following conclusions. 1) Those basins have experienced four stages of tectonic sedimentary evolution, including subduction stage, basin-forming stage, precipitation stage and compression stage. 2) The sedimentary fillings was controlled by tectonic evolutions. Volcanic rocks and metamorphic basement mainly developed in the subduction stage, with marine clasts in some local areas. Marine sediments took dominance in the basin-forming stage, accompanied by volcanic activities. Meanwhile, the continental clasts also developed in some local areas. Marine facies and delta facies both developed in the precipitation stage and compression stage while some basins also developed lacustrine facies in the compression stage. 3) Different types of basins possess different features of tectonic sedimentary evolution. The fore-arc basin is 3100 meters thick on average. The evolution of those basins were primarily controlled by compression and plate subduction. Its basin-forming stage is relatively short and neritic facies and delta facies deposited in this period, with continental and deep-sea facies in some local areas. The back-arc basin is 5300 meters thick on average. Those basins have experienced a long basin-forming stage under the influence of subduction retreat and back-arc oceanic crust expansion. Water became shallow from subduction stage to compression stage with deep sea-bathyal facies to shallow marine-delta facies. In addition, the gravity flow deposits were also well developed, with fluvial-lacustrine facies in local areas. The continental rift basin is 6100 meters thick on average. Those basins underwent a long basin-forming stage with double fault structure. The neritic facies mainly developed in basin-forming stage. The tidal flat, delta, shallow sea facies and fluvial facies mainly developed in compression stage, with carbonate rock in local areas. From the above, we clearly summarized the Cenozoic tectono-sedimentary evolution characteristics of sedimentary basins in the Western Pacific, laying a good geological foundation of oil and gas exploration and development for the future.