Sedimentary environments of the volcanic island arc zone in the Chindwin-Shwebo Basin, Myanmar

There were gradations of the sedimentary facies from the coastal plain in the northeastern part to the littoral-shallow sea in the southwestern part in the Chindwin-Shwebo Basin, Myanmar prior to the Pliocene. The delta facies is less developed, and the volcanic rocks interruptedly display a NS-directed arrangement in the central part of the Basin. The tectonism, volcanism and sea-level changes are responsible for the formation of the sedimentary environments. The broad and gentle tectonic settings are interpreted as the key factors for the formation of the coastal plain and littoral-shallow sea environments. The volcaniclactics from the volcanic activities within the island arc zone during the Cretaceous to the Miocene not only provided sediment sources for the normal deposition of the strata, but also play a destructive role in the propagation and preservation of organisms. The sea-level changes are also considered as the important factors in controlling the distribution of depositional systems.