缅甸钦敦-睡宝盆地火山岛弧带沉积环境分析

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

关键词:  火山岛弧带  沉积环境  构造运动  火山活动  海平面变化

Key words:  volcanic island arc zone  sedimentary environment  tectonism  volcanism  sea-level change

摘要:

缅甸钦敦-睡宝盆地在上新世之前的沉积相主体由东北部的海岸平原向西南逐渐过渡到滨浅海,三角洲相对不发育,火山岩呈南北向断续分布在盆地的中部。构造运动、火山活动和海平面升降决定了火山岛弧带的沉积环境。宽缓的构造背景是形成海岸平原-滨浅海沉积环境的决定因素;岛弧带的火山活动自白垩纪至中新世整体表现出较持续的喷发,形成的火山碎屑不仅参与了正常的地层沉积,还对古生物的繁殖和化石的保存起到破坏作用。海平面升降也是控制沉积体系展布的重要因素。

Abstract:

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.