现代三角洲动力沉积过程与沉积体系发育机制评述:以珠江三角洲为例

Reviews on Sediment Dynamics and Depositional Systems in the Modern Delta, with a Particular Emphasis on the Pearl River Delta

全球变化和海平面上升背景下大型三角洲体系的响应机制与应对措施,将是关系到区域和全局性的环境与生态安全问题。现代珠江三角洲是一个受构造活动与地貌控制、河流与潮汐共同作用的内陆架浅水型三角洲,在世界大型海岸三角洲研究中具有独特的地位。过去由于水下三角洲勘探与研究不足,尤其动力沉积过程与潮汐沉积地层研究的薄弱,致使现代珠江三角洲发育演变规律长期成为学术界争论的焦点问题。本文将从三角洲类型与地层模型、三角洲动力沉积过程、珠江三角洲等三个方面进行评述,提出三角洲研究的突破口在于从三个时间尺度,即现代动力沉积过程、百年尺度的高分辨率沉积地层和千年尺度的沉积体系,探讨三角洲发育演变与动力沉积机制。

The responses and countermeasures of coastal megadeltas to global change and intense human activities are highly involved with environmental and ecological safeties over regional and even global scales. The modern Pearl Riverdelta (approximately 6000 years B.P.) is an inner-shelf or shoal-water delta controlled by tectonics and topography, and subject to combined fluvial and tidal forcing, and thus it plays a unique role among coastal megadeltas in the world. Since there is a great lack in exploration on the submerged delta and a large gap in understanding sediment dynamics and tidal stratigraphy, the evolution of the modernPearldelta has longly been a disputing focus in the sedimentological community. This paper will focus on three themes: classification and model of deltas, sediment dynamics, and thePearl Riverdelta evolution. Then it follows that future investigations should be devoted to three different processes or systems with distinct time scales in the delta or estuary: sediment dispersal, stratigraphic succession, and depositional system, and further to understanding the evolution and mechanism of the delta.